BIOCHEM REVIEWER - Identification of Nucleic Acid as

information molecules
INTRODUCTION TO CHEMISTRY
OXIDATION REDUCTION REACTIONS
Importance of biochemistry
 Involve electron transfer between
 The chief goal of biochemistry is to
molecules
understand the structure and behavior
 Dehydrogenase – enzyme for redox
of biological molecules
reactions
 It is concerned with the
 Makes use of cofactors (accepts or
physicochemical processes underlying
donates electrons)
digestion, absorption, circulation,
respiration, metabolism, growth and ANABOLISM
reproduction
 Combines small molecules to form
 Understanding of Biochemistry allows a
complex molecules
better comprehension of the different
 Anabolic reactions often involve
processes happening in the different
chemical reductions
organs of the body.
 The reducing power is provided by the
 It is related to all other major subjects
electron donor NADPH
such as Anatomy, Physiology, Histology,
 Anabolism is a divergent process in
Medicine
which a few biosynthetic precursors
 Helps understand make up of
form a wide variety of polymeric or
chemicals and/or materials and
complex products
medicines use in the practice of
profession CLASSIFY THE FOLLOWING AS (A)
ANABOLIC AND (C) CATABOLIC
HISTORY OF BIOCHEMISTRY
1. Synthesis of a polysaccharide from
Emil Fischer – studied the catalytic effect
monosaccharides
of yeast enzymes on a simple reaction, the
2. Hydrolysis of pentasaccharide to
hydrolysis of sucrose
monosaccharide
 Substance + enzyme = intermediate 3. Formation of nucleotide
compound fromphosphate, sugar and base
 Proposed the lock and key theory of 4. Hydrolysis of triacylglycerol
enzyme action (enzyme – lock; 5. Protein formation from amino acids
substrate – key)
IMPORTANCE OF BIOCHEMISTRY
 Almost all reactions that occur in living
cells are catalyzed by enzymes and Abnormalities in the oral cavity and
thus proceed at very high rates illnesses involving the digestive system:
Carl Neuberg – introduced the term FOOD > INGESTED > DIGESTED >
Biochemistry in 1903 and thus was named TRANSPORTED > METABOLIZED STORED >
as the father of biochemistry EXCRETED
TWO MAJOR BREAKTHROUGHS IN THE NO OR LIMITED provision of energy for the
HISTORY OF BIOCHEMISTRY different cells of the body, NO OR LIMITED
maintenance of normal body functioning,
- Discovery of enzymes and its roles
NO OR LIMITED regulation of body
processes, building and repair of tissues
Faulty health condition > onset of diseases
(physical, mental, social)
WHAT ARE THE DIFFERENT BIOMOLECULES?
Nucleic acids
* Are polymers composed of monomers
called Nucleotides
* Nucleotides - contain a 5-carbon sugar, a
heterocyclic nitrogeneous base and at
least one phosphate group
* In ribonucleotides, the sugar is ribose
* In deoxyribonucleotides, the sugar is
deoxyribose
* The two nucleic acids are
* DNA - deoxyribonucleic acid
IMPORTANCE OF BIOCHEMISTRY
* RNA - ribonucleic acid
* FOOD > ingested > digested > absorbed
Proteins
> transported > metabolized > stored >
* Contain an amino group and a excreted
carboxylate group as well as a side chain
 provision of energy for the different cells
* Made up of different amino acids joined of the body, maintenance of normal
by an amide bond or a peptide bond body functioning, regulation of body
processes, building and repair of tissues
* Its shape is determined by the sequence
 Good health condition (physical,
of its amino acid residues which is
mental, social)
encoded by a gene
BIOCHEMISTRY DEFINED
* The protein function depends on its 3D
structure or conformation * Concerned with the biological molecules
of living organisms; its structure, properties
and functions.
* The study of biomolecules and the
different processes they undergo inside the
human body as they affect the life, health
and nutrition status of the individual
CATABOLISM
* Functions
* Serve to capture chemical energy from
the degradation of energy-rich fuel
molecules
* Allows molecules in the diet to be
converted into building blocks
MOLECULAR PHYSIOLOGY
2 types of metabolic pathways
* Linear metabolic pathway - series of
reactions generates a final product
* A –> B –> C -> D BRANCHES OF BIOCHEMISTRY
* Molecular Angtomy
*Each reaction is catalysed by an enzyme The study of the structure of biomolecules,
* Cyclic - series of reactions regenerates their make up, composition
the first reactant * Molecular Physiology
* A -> B Deals with the function of the different
I I biomolecules

D <- C PROCESSES UNDERGONE BY

BIOMOLECULES
BIOCHEMISTRY DEFINED
D. UTILIZATION
* The study of the chemical processes that
go on in living matter. * the process by which the absorbed
nutrients are used by the different cells for
*It is a field where principles of biology, a specific purpose or function
chemistry and physiology are applied.
* e.g. ATP (adenosine triphosphate) -
METABOLISM energy used by all cells in the body
2 PHASES OF METABOLISM HISTORY OF BIOCHEMISTRY
* ANABOLISM - is the constructive phase of * Freidrich Wohler (1828)
metabolism. It is the process of synthesis
required for the growth of new cells and * His experiment laid the foundation for
the maintenance of all tissues modern biochemistry
* He heated ammonium cyanate
(inorganic compound) to form urea
(organic compound found in urine and
blood)
* Demonstrated that organic compounds
need not necessarily be formed in living
organisms
* Father of Organic Chemistry * Conversion of building blocks to simple
intermediates
PROCESSES UNDERGONE BY
* Sugars usually enter the glycolysis
BIOMOLECULES
pathway in the form of glucose or fructose
A. DIGESTION which are eventually converted to acetyl
CoA
* it refers to the breakdown of large
foodstuffs into smaller particles * Amino groups are removed from amino
acids and the remaining carbon skeletons
* 2 forms
enter the catabolic processes at many
Physical digestion - the mechanical steps of glycolysis and the citric acid cycle
conversion of big food into smaller
* Fatty acids are converted to Acetyl COA
absorbable particles
* Oxidation of acetyl CoA and the
Chemical Digestion - the conversion of big
production of ATP
food particles into smaller absorbable
forms with the participation of enzymes, BIOMOLECULES
hormones and digestive juices
* any organic or inorganic matter which
MOLECULAR PHYSIOLOGY OF THE when introduced into the body (eaten,
injected or inhaled) will either positively or
DIFFERENT BIOMOLECULES
negatively affect vital life processes. E.g.
o Work within cells food, medicine, chemicals, poisons

* Mechanical work - a change of location * carbon-containing compounds that

or posture of an organism, cell or cellular make up the various parts of the living cell
structure and carry out the chemical reactions that
enable it to grow, maintain and reproduce
* Osmotic or electrical work - compounds
itself, and use and store and energy
or ions are often moved against a
concentration gradient ELECTRON ACCEPTORS OR DONORS USED
BY DEHYDROGENASE ENZYMES
* Synthetic work - a change in chemical
bonds required to generate complex Oxidize Reduce Meaning ATP
molecules from simple precursors d form d form equivale
(electro (electro nt
o Provision of energy n n
recepto donor)
CATABOLISM r)
NAD+ NADH Nicotinamide 2.5
3 stages of Catabolism Adenine
Dinucleotide
Hydrolysis of complex molecules into (hydride)
component building blocks FAD+ FADH Flavine 1.5
adenine
* Proteins to amino acids dinucleotide
(hydride)
* Polysaccharides to monosaccharides FMN FMNH Flavin 1.5
mononucleoti
* Triglycerides to free fatty acid de hydride
PROCESSES UNDERGONE BY
BIOMOLECULES
E. INTEGRATION INTO TISSUES
* the process by which the absorbed
nutrients are included or incorporated into
the structural framework of the body like in
the bones, muscles, teeth, hair, skin, joints,
and ligaments
METABOLIC PATHWAYS
* Importance of metabolic pathways
* It permits control of the rate and direction
of the cellular activity
* It prevents very large chemical bond
energy releases which would be
damaging to cells
* It permits branch points
* Allows pathways to be directed (under
different circumstances)to different end
products
Metabolic pathways
* Organized sequence of chemical
reactions
* Chemical reactions are needed to
extract the chemical bond energy from
energy supplying compounds and to
synthesize different biological molecules
* Enzymes - controls the metabolic
pathways by catalysing each of the steps
in a pathway
* Hormones - intercellular messengers that
helps regulate the amount of substrate
and enzymes
 * These processes are concerned with the
role of the cells of an organism to transform
energy, maintain their identity and
reproduce
PROCESSES UNDERGONE BY
BIOMOLECULES
B. ABSORPTION
* it refers to the diffusion or movement or
nutrients and other ingested materials from
the small intestines (jejunum) into the blood
stream
HISTORY OF BIOCHEMISTRY
* the process is facilitated by microvilli
- DISCOVERY OF ENZYMES AND ITS ROLES which are mobile, fingerlike projections
that increases the absorptive area of the
* Enzymes - catalysts of biological reactions
GIT
* Starch –amylase glucose
CATABOLISM
* Berzelius - formulated the general
* CATABOLISM - is the destructive phase of
principles of catalysts
metabolism.
* Lead to the recognition that ptyalin in
* continuous process concerned with the
saliva, pepsin of gastric juice and amylase
production of the energy required for all
of sprouted malt were biological catalysts
external and internal physical activity
OXIDATION REDUCTION REACTIONS
* It involves
Oxidation
*maintenance of body temperature
* Involves loss of electrons from a molecule
*degradation of complex chemical bits
* Often accompanied by a loss of one or into simpler substances that can be
more hydrogen atoms from the molecule removed as waste products from the body
through the kidneys, intestines, lungs and
Reduction
skin
* Involves gain of electrons by a molecule
* NB. Anabolic and catabolic processes
* Often accompanied by a gain of one or should be proportionately done in order to
more hydrogen atoms by the molecule maintain the biological equilibrium or
homeostasis in the living body
METABOLISM
WHAT ARE THE DIFFERENT
* Sum total of the physical and chemical
processes and reaction taking place BIOMOLECULES?
among the ions, atoms and molecules of
Lipids
the living body
* Generally water-insoluble organic
compounds
* The simplest lipidpare the fatty acids, long * includes simple sugars
chain hydrocarbons with a carboxylate (monosaccharides) and their polymers
group at one end (polysaccharides)
* Lipids form the biological membrane * contain several hydroxyl groups
(polyalcohols)
* sugar structures can be represented in
several ways
Fischer Projection - linear representation
* Open chain form
* Ring form (biochemical form)
* Haworth Projection
C. ASSIMILATION
* it refers to the selective uptake of specific
PROCESSES UNDERGONE BY nutrients by an organ in the body in other
words, the absorbed nutrients are not
BIOMOLECULES
uniformly distributed in the body
G. EXCRETION
* For example:
process by which metabolic wastes are
* Bones and teeth would take up more of
finally expelled or removed from the body
the calcium and phosphorus
* these wastes when allowed to
* Thyroid gland would take up most of
accumulate inside will destroy cells and
iodine
tissues so these must be dispensed off fast
* Hair would take up zinc
* Organs of excretion:
* Bone marrow take most of the iron and
* Kidneys - urine
copper to make RBC
* Lungs - volatile acids in the form of CO2
* Adipose tissues would take up most of the
* Skin - sweat (hypotonic NaCI) fat

* GIT - stool or feces or undigested residue * Liver would take up most of the sugars
of food (excreted through defecation
HISTORY OF BIOCHEMISTRY
WHAT ARE THE DIFFERENT
IDENTIFICATION OF NUCLEI ACID AS
BIOMOLECULES? INFORMATION MOLECULES

Carbohydrates * Oswald Avery, Colin Macleod and

Maclyn McCarty (1944)
* an organic compound containing
carbon, hydrogen and oxygen * They extracted DNA from a tox)strain of
Streptococcus pneumonia and mixed the
* hydrogen-oxygen ratio is 2:1
DNA with a non-toxic strain
* James D. Watson and Francis H.C. Crick
(1953)
* They deduced the 3D structure of DNA
* They discovered DNA replication process,
which then transmits biological information
to succeeding generation
* The central Dogma
* States that the information encoded in
DNA is transcribed to RNA and then
translated to protein
* DNA –Transcription RNA –translation-->

CHON
PROCESSES UNDERGONE BY
BIOMOLECULES
F. BIOTRANSFORMATION AND METABOLIC
DEGRADATION
* the process by which all harmful and
potentially toxic materials introduced into
the bodylike food, preservatives, food
coloring, and chemicals like formalin) are
inactivated or detoxified by the liver into
something non-toxic or even less toxic thus,
no significant harm is done on the body
* 2 forms
Metabolic degradation - breakdown of
complex substances into simpler ones that
act as active metabolites or end products
for energy production
Biosynthesis - combination of simpler
substances to build complex substances
for cell repair, growth and reproduction
BIOCHEM REVIEWER  * FOOD > ingested > digested >
INTRODUCTION TO CHEMISTRY absorbed > transported >
metabolized > stored > excreted
 Biochemistry Defined  provision of energy for the
 Concerned with the biological different cells of the body,
molecules of living organisms; maintenance of normal body
its structure, properties and functioning, regulation of body
functions. processes, building and repair
 The study of biomolecules and of tissues
the different processes they  Good health condition (physical,
undergo inside the human body as mental, social)
they affect the life, health and Abnormalities in the oral cavity
nutrition status of the and illnesses involving the
individual digestive system:
 The study of the chemical  FOOD > INGESTED > DIGESTED >
processes that go on in living TRANSPORTED > METABOLIZED
matter. STORED > EXCRETED
 It is a field where principles  NO OR LIMITED provision of
of biology, chemistry and energy for the different cells
physiology are applied. of the body, NO OR LIMITED
*inorganic>organic>biochemistry maintenance of normal body
functioning, NO OR LIMITED
 Importance of biochemistry regulation of body processes,
 The chief goal of biochemistry building and repair of tissues
is to understand the structure  Faulty health condition > onset
and behavior of biological of diseases (physical, mental,
molecules social)
 It is concerned with the
physicochemical processes HISTORY OF CHEMISTRY
underlying digestion, absorption,  Freidrich Wohler (1828)
circulation, respiration,  His experiment laid the
metabolism, growth and foundation for modern
reproduction biochemistry
 Understanding of Biochemistry  *He heated ammonium cyanate
allows a better comprehension of (inorganic compound) to form
the different processes urea (organic compound found in
happening in the different urine and blood)
organs of the body  * Demonstrated that organic
 It is related to all other major compounds need not necessarily
subjects such as Anatomy, be formed in living organisms
Physiology, Histology, Medicine  * Father of Organic Chemistry
 Helps understand make up of  (Robert Burns Woodward- father
chemicals and/or materials and of modern organic chemistry)
medicines use in the practice of (UREA IS ASSOCIATED IN PROTEIN
profession METABOLISM)

TWO MAJOR BREAKTHROUGHS IN THE

HISTORY OF BIOCHEMISTRY
- Discovery of enzymes and its James D. Watson and Francis H.C.
roles Crick (1953)
- Identification of Nucleic Acid as -They deduced the 3D structure of
information molecules DNA
-They discovered DNA replication
DISCOVERY OF ENZYMES AND ITS ROLES process, which then transmits
 Enzymes - catalysts (enhance) biological information to
of biological reactions succeeding generation
*Hormones are regulators* The central Dogma
 Starch –amylase -> glucose -States that the information
 Berzelius - formulated the encoded in DNA is transcribed to
general principles of catalysts RNA and then translated to protein
 -vital force theory as far as ( DNA – Transcription RNA –
organic chemistry is concern translation--> CHON or protein-
(Lead to the recognition that WOULD FORM DIFFERENT BIOLOGICAL
ptyalin in saliva, pepsin of PRODUCTS)
gastric juice and amylase of
sprouted malt were biological BRANCHES OF BIOCHEMISTRY
catalysts) Molecular Anatomy -The study of the
 Emil Fischer – studied the structure of biomolecules, their
catalytic effect of yeast make up, composition
enzymes on a simple reaction, Molecular Physiology -Deals with
the hydrolysis of sucrose the function of the different
 Substance + enzyme = biomolecules
intermediate compound
 Proposed the lock and key BIOMOLECULES
theory of enzyme action (enzyme -any organic or inorganic matter
– lock; substrate – key) which when introduced into the body
Almost all reactions that occur (eaten, injected or inhaled) will
in living cells are catalyzed by either positively or negatively
enzymes and thus proceed at very affect vital life processes. E.g.
high rates food, medicine, chemicals, poisons
 Carl Neuberg – introduced the -carbon-containing compounds that
term Biochemistry in 1903 and make up the various parts of the
thus was named as the father of living cell and carry out the
biochemistry. chemical reactions that enable it
- discovered the enzyme to grow, maintain and reproduce
called carboxylase itself, and use and store and
energy
IDENTIFICATION OF NUCLEI ACID AS
INFORMATION MOLECULES Carbohydrates
Oswald Avery, Colin Macleod and -an organic compound containing
Maclyn McCarty (1944) carbon, hydrogen and oxygen
- They extracted DNA from a toxic -hydrogen-oxygen ratio is 2:1
strain of Streptococcus pneumonia
-includes simple sugars
and mixed the DNA with a non-toxic
(monosaccharides-simplest) and
strain
their polymers (polysaccharides-
complex)
 contain several hydroxyl
groups (polyalcohols)
-sugar structures can be Nucleic acids
represented in several ways -Are polymers composed of
Fischer Projection - linear monomers called Nucleotides
representation * Nucleotides - contain a 5-
-Open chain form carbon sugar, a heterocyclic
- Ring form (biochemical form) nitrogeneous base and at least
-Haworth Projection one phosphate group
* In ribonucleotides, the sugar
is ribose
* In deoxyribonucleotides, the
sugar is deoxyribose
* The two nucleic acids are
1. DNA - deoxyribonucleic acid
2. RNA - ribonucleic acid

MOLECULAR PHYSIOLOGY OF THE

DIFFERENT BIOMOLECULES
o Work within cells
* Mechanical work - a change of
Proteins location or posture of an
- Contain an amino group and a organism, cell or cellular
carboxylate group as well as a structure eg.(moving place from
side chain (simplest-amino acids) one place to another)
-Made up of different amino * Osmotic or electrical work -
acids joined by an amide bond or compounds or ions are often
a peptide bond moved against a concentration
-Its shape is determined by the gradient
sequence of its amino acid -relay of information from one
residues which is encoded by a organ to another
gene -nerve impulse transmission
-The protein function depends on * Synthetic work - a change in
its 3D structure or conformation chemical bonds required to
generate complex molecules from
Lipids simple precursors eg.(weight
-Generally water-insoluble gain, glucose stored as glycogen)
organic compounds o Provision of energy
-The simplest lipid pare the
fatty acids, long chain METABOLISM
hydrocarbons with a carboxylate -heart of chemistry or
group at one end biochemistry
-Lipids form the biological -Sum total of the physical and
membrane chemical processes and reaction
taking place among the ions, maintain the biological
atoms and molecules of the equilibrium or homeostasis in
living body (transformation of the living body
energy) * Functions
2 PHASES OF METABOLISM -Serve to capture chemical
* ANABOLISM - is the energy from the degradation of
constructive phase of metabolism. energy-rich fuel molecules
It is the process of synthesis - Allows molecules in the diet
required for the growth of new to be converted into building
cells and the maintenance of all blocks
tissues (Key words: SYNTHESIS, 3 stages of Catabolism
FORMATION) -Hydrolysis of complex molecules
-Combines small molecules to into component building blocks
form complex molecules - Proteins to amino acids
-Anabolic reactions often -Polysaccharides to
involve chemical reductions monosaccharides
-The reducing power is provided -Triglycerides to free fatty
by the electron donor NADPH acid
-Anabolism is a divergent -Conversion of building blocks
process in which a few to simple intermediates
biosynthetic precursors form a -Sugars usually enter the
wide variety of polymeric or glycolysis pathway in the form
complex products (AMINO ACID IS of glucose or fructose which are
AMONOMER AND PROTEINS ARE eventually converted to acetyl
POLYMER) CoA
* CATABOLISM - is the - Amino groups are removed from
destructive phase of metabolism. amino acids and the remaining
-continuous process concerned carbon skeletons enter the
with the production of the catabolic processes at many
energy required for all external steps of glycolysis and the
and internal physical activity citric acid cycle
-It involves maintenance of body -Fatty acids are converted to
temperature Acetyl COA
-(Key words: HYDROLYSIS, - Oxidation of acetyl CoA and
OXIDATION, CONVERSION) the production of ATP
-degradation of complex chemical
bits into simpler substances CATABOLIC PATHWAY VS. ANABOLIC
that can be removed as waste PATHWAY
products from the body through CATABOLIC- degrative pathway
the kidneys, intestines, lungs -breaks down complex
and skin biomolecules to a few simple
* NB. Anabolic and catabolic molecules
processes should be ANABOLIC- synthetic pathway
proportionately done in order to
-form complex end products from
simple precursors.
(proteins to amino Metabolic pathways
acids=catabolic/ amino acids to * Organized sequence of chemical
proteins=anabolic) reactions
* Chemical reactions are needed
OXIDATION REDUCTION REACTIONS to extract the chemical bond
-Involve electron transfer energy from energy supplying
between molecules compounds and to synthesize
Dehydrogenase – enzyme for different biological molecules
redox reactions * Enzymes - controls the
- Makes use of cofactors metabolic pathways by catalysing
(accepts or donates electrons) each of the steps in a pathway
Oxidation * Hormones - intercellular
* Involves loss of electrons messengers that helps regulate
from a molecule the amount of substrate and
* Often accompanied by a loss of enzymes
one or more hydrogen atoms from Importance of metabolic
the molecule pathways
Reduction * It permits control of the rate
* Involves gain of electrons by and direction of the cellular
a molecule activity
* Often accompanied by a gain of * It prevents very large
one or more hydrogen atoms by chemical bond energy releases
the molecule which would be damaging to cells
Oxidi Redu Meaning ATP * It permits branch points
zed ce d equival * Allows pathways to be directed
form form e nt
(under different
(elec (ele
tron ctro circumstances)to different end
recep n products
tor) dono
r) 2 types of metabolic pathways
NAD+ NAD Nicotinamide 2.5 Linear metabolic pathway -
H Adenine series of reactions generates a
Dinucleotide final product
(hydride) * A –> B –> C -> D
FAD+ FAD Flavine 1.5 *Each reaction is catalysed by
H adenine an enzyme
dinucleotide Cyclic - series of reactions
(hydride) regenerates the first reactant
FMN FMN Flavin 1.5 * A -> B
H mononucleoti | |
de hydride D <- C
 - Thyroid gland would take up
most of iodine * Hair would take
PROCESSES UNDERGONE BY up zinc
BIOMOLECULES - Bone marrow take most of the
A. DIGESTION - it refers to the iron and copper to make RBC
breakdown of large foodstuffs - Adipose tissues would take up
into smaller particles most of the fat
2 forms -Liver would take up most of the
A. Physical digestion - the sugars
mechanical conversion of big
food into smaller absorbable E. INTEGRATION INTO TISSUES
particles -the process by which the
B. Chemical Digestion - the absorbed nutrients are included
conversion of big food particles or incorporated into the
into smaller absorbable forms structural framework of the body
with the participation of like in the bones, muscles,
enzymes, hormones and digestive teeth, hair, skin, joints, and
juices ligaments
C.
B.ABSORPTION - it refers to the F. BIOTRANSFORMATION AND
diffusion or movement or METABOLIC DEGRADATION
nutrients and other ingested - the process by which all
materials from the small harmful and potentially toxic
intestines (jejunum) into the materials introduced into the
blood stream bodylike food, preservatives,
- the process is facilitated by food coloring, and chemicals
microvilli which are mobile, like formalin) are inactivated
fingerlike projections that or detoxified by the liver into
increases the absorptive area of something non-toxic or even less
the GIT toxic thus, no significant harm
is done on the body
D. ASSIMILATION -it refers to 2 forms
the selective uptake of specific Metabolic degradation -
nutrients by an organ in the breakdown of complex substances
body in other words, the into simpler ones that act as
absorbed nutrients are not active metabolites or end
uniformly distributed in the products for energy production
body Biosynthesis - combination of
For example: simpler substances to build
- Bones and teeth would take up complex substances for cell
more of the calcium and repair, growth and reproduction
phosphorus
G. EXCRETION process by which
metabolic wastes are finally
expelled or removed from the
body
-these wastes when allowed to
accumulate inside will destroy
cells and tissues so these must
be dispensed off fast
- Organs of excretion:
* Kidneys - urine
* Lungs - volatile acids in the
form of CO2
* Skin - sweat (hypotonic NaCI)
* GIT - stool or feces or
undigested residue of food
(excreted through defecation
PH AND THE CHEM OF RESPIRATION Henderson-Hasselbach Equation
DEFINITION OF TERMS • This fundamental equation relates the
❖ ACID and BASE hydrogen concentration in a solution of
-Is a potential proton donor and base is an acid or a base to its dissociation
a potential proton acceptor. (Bronsted- constant, and to the relative
Lowry) Thus the weak acid HA is an acid concentration ofthe dissociated and
because it can donate a proton. undissociated forms of the acid or base
-Hydrogen ion concentration of solution
is measured in terms of pH value, which
is the logarithm of the number of liters
of a solution containing one gram of H
ions
*Acid has a pH below 7-0*
*Base has a pH higher than 7-14*
-All neutral solutions have the same pH
value as water.
-Values above 7 are alkaline, that is, OH Buffer substances
ions exceed the H ion. • Are those which prevent the change
-Values below 7 are acid in reaction; of the reaction of solution upon
the H ions exceed OH ions addition of small amounts of acids or
-The determination of H ion bases(no effect).
concentration of different solutions • Buffer solutions consist of mixtures of
may be done either by electrometric weak acids and their salts or weak bases
method or by the use of standard and their salts. When an alkali is added
buffers and indicators (colorimetric). to a buffer solution, the excess
OH(hydroxyl) ion combine with the H
HYDROGEN & HYDROXYL ions of the buffer solution to form
• H and OH determines the acidity or water.
alkalinity of a particular substance. *All body fluids except gastric juice,
• Acids and bases which dissociate
more readily are capable of liberating
greater number of H or OH ions thus
called strong acids or bases.
Ex:hydrochloric acid, sodium hydroxide
(strong base) urine and milk are slightly alkali and this
• Those which ionize only slightly reaction are maintained by the Buffer
liberate comparatively less H or OH ions substances*
and are termed weak acids or bases. *Blood has pH normally 7.4-7.45*
• Water is neutral since there is equal *A mark reduction means ACIDOSIS and
number of H and OH liberated an increase is known as ALKALOSIS*
•H20 > H+ +OH- (chemical formula of
water)
Chemistry of Respiration *Heme- iron part
•Respiration is referred to as the
exchange of gases between the outside
air and the body.
•External respiration is the exchange
occurring between the outside air and
the venous blood through the lungs.
•Internal respiration is the exchange
between the blood and the tissues.
*250 ML OXYGEN MINUTE AT REST AND
INHALATION OF 200 ML CARBON
DIOXIDE* *globin- protein part
•Hemoglobin molecules can transport
Physical Theory of Respiration up to four O2’s
• The exchange of gases between the •When 4 Op's are bound to
outside air, the blood and the different hemoglobin, it is 100% saturated
tissues of the body, is governed with fewer O2's it is partially saturated
by the physical law of diffusion. •Hemoglobin's affinity for O2 increases
• Gas will flow from a higher to a lower as its saturation increases
tension. • Oxygen binding occurs in response to
• Tension is the pressure exerted by gas the high Po2 in the lungs
in solution.
• Chemical control of respiration is Oxyhemoglobin Formation
exerted directly upon the respiratory -oxygen molecules reversibly attached
centers in the medulla and upon the to the heme portion of hemoglobin
chemical receptors located at the -Heme unit contains iron (Fe+2) which
bifurcation of the common carotid provides the attractive force
arteries and the arch of the aorta. -O2+HB =HbO2

Chemical Control of Respiration Maximum amount of O that can

• CO2is the main factor regulating the combine with HEMOGLOBIN of blood
rate and depth of respiration • Normal Hb -15 gms/100 ml of blood
• Increasing the cO2 content of the • Each gm of Hb can bind 1.34 ml of O,
blood ->increased rate and depth of (Hufner factor)
respiration > increased pulmonary • The oxygen saturation of the BC
ventilation leaving the lungs is
•Diminution of the pCO2 -> slow and around 96% while that of the venous
Shallow respiration > diminished Hgb is around 64%. This implies that
respiration and decreased CO2 32% of the oxygen has been delivered
elimination > restoration of pCO2. to the tissues.
• Total O bound with Hb: 15x1.34 x
.32=6.4 ml O2 is supplied to tissues per
100ml of blood passing through the
capillaries
 Factors affecting the dissociation of *Carbon Dioxide is carried as carbonic acid 5%
oxyhemoglobin as dissolved carbonic acid, 20% carbamino
compound, 75% bicarbonate

Chemical Theory of Respiration

• 1. The wall of the RBC is a membrane
permeable to water, CO2, carbonic acid,
chlorine and hydrogen ions, but not to
hemoglobin and plasma proteins and only
slightly to Na(sodium) and K(potassium) ions.
• 2. Most of the Na ions in the plasma, while
those of K are in the cells.
• 3. Most of the proteins in the BC are
combined with K, the amount
varying in the different stages of the cycle.
• 4. In the RBC (not in the plasma) there is an
enzyme, the carbonic anhydrase, which hastens
1. *above 70 milligrams mercury= light the transformation of carbon dioxide and
effect to oxyhemoglobin dissociation water into carbonic acid and vice versa.
*below 50 milligram mercury= increase
dissociation Acid- Base Balance
2. One factor of carbon dioxide • The acid- base balance depends upon the
3. Happens when exercising and ratio of H2CO3 (carbonic acid) to BHCO3(1:20)
excretion of carbon dioxide (bicarbonate acid)
4. In wam blooded animals hemoglobin • Normal metabolic Activities of the body ->
gives oxygen more readily when passing production of relatively large amounts of acids
from high to low tension including carbonic, sulfuric, phosphoric and
5. Electrolytes are charged elements organic acids, like lactic acid and hydroxybutyric
acids.
Carbon Dioxide Transport • Sulfur and phosphorus containing proteins -
>(oxidized) give rise to H2SO4 (sulfuric acid) and
H3PO4 (phosphoric acid)
• Fruits and vegetables (rich in positive radicals
like Na, K,Ca) liberate potentially basic
substances.

The maintenance of this normal pH is brought

about by several factors
• 1. the buffer systems of the blood
•2. CO2 elimination through the lungs
• 3. Renal excretion of acids and bases
• Under normal condition, urinary pH is about
6.0
• Under certain conditions the pH of the urine
may vary from 4.5 to 8.2
• 4. Renal formation of ammonia- base
conservation
ABNORMALITIES OF ACID-BASE BALANCE
• Metabolic Acidosis
• Produced whenever available base is
decreased although the total base may remain
unchanged.
• Takes place to during fasting and starvation
where there is increased mobilization of fat to
provide the necessary energy reqt > formation
of ketone bodies
• Occurs in severe diarrhea where there is loss
of large amount of Na.

• Metabolic Alkalosis
• Occurs when the alkali reserve is increased
although total base may remain unchanged.
• X's (Excessive) vomiting and loss of large
amount of Cl > increased Na to bind with HCO3
• X's use of diuretics and administration of large
doses of NaHCO3

• Respiratory Acidosis (Hypoventilation)

• Occurs in any condition in which there is
interference with the exchange of gases within
the lungs so that CO, is not adequately blown
off.
• May happen in marked narcosis from drugs,
CNS depression from any cause, emphysema
and bronchiectasis

•Respiratory Alkalosis (Hyperventilation)

•Produced in any condition causing
hyperventilation, when this is not the result of
interference with the gaseous exchange in the
lungs.
• Occurs among nervous Px who are breathing
rapidly due to some frightening symptom or
situation
• Can be seen in high fevers, CNS lesions and
anoxia of the cardiac type or due to high
altitudes
• The increased ventilation blows off large
amounts of CO2 so that the plasma carbonic
acid concentration is decreased.
CELL AND ITS FUNCTIONS
-Is the fundamental unit of living matter.
-fundamental unit of biological activity and
is capable of reproduction
FUNCTIONS:
1. Transport of substances through the
cell membrane
2. Energy metabolism
3. Synthesis of protein and other
cellular substances
4. Pinocytosis- ameoboid or
“chemotaxic” movement of cells
toward chemical stimulus

CELL DIVERSITY
-the average adult has nearly 100 trillion
cells
-There are about 22 different types of cells
-permits organizations of cells into more
complex tissues and organs

General Rules:
• All organisms are composed of one
or more cells
• All living cells came from other living
cells
• Cells are the basic units of structure
and function of an organism
• Cells has variety of shapes and sizes
• There is only 1 nucleus in 1 cell
except for RED BLOOD CELLS AND
PLATELETS (non nucleated)
(Epithelial Cell=1 cell),
TYPES OF CELLS
Eukaryotic Cells Prokaryotic Cells
TYPES OF CELLS
-contains a -does not include
❖ Somatic cells- make up the living
nucleus and a nucleus or
structure of the body (body cell or
organelles (more specialized
autosome
developed) organelles
❖ Sex Cells-germs cells (involved in
-Lack membrane sexual reproduction)
bound nucleus
and organelles
-Genetic -Genetic material
instructions are is naked in the
bound in the cytoplasm
nucleus and
carried out by the
Ribosomes
CELL STRUCTURES ❖ RECESSIVE TRAIT- one which may be
❖ Nucleus- double membrane, control seen only in a minority of offsprings
center of the cell, contains -Trait may even disappear in one
chromosomes, each of which generation but will re-appear in
consists of a single molecule of DNA succeeding generations
(CHROMOSOMES- contains TYPES OD EXPRESSION OF
thousands of hereditary called HEREDITARY TRAITS
genes) ❖ PHENOTYPE- physical observable
❖ Nuclear envelope- a double aspects of hereditary as handed
membrane that separates the down from generation to generation
nucleus from cytoplasm or it Eg: type of hair, eyes, dimples,
separates the genetic material from bridge of the nose
the rest of the cell.
❖ Nuclear pores- numerous openings ❖ GENOTYPE- non-observable, non-
in the nuclear envelope and it physical aspects of heredity
control movement of substances Eg: IQ, talent,allergy
between the nucleus and cytoplasm
❖ Nucleolus- small, discrete, spherical, PLASMA MEMBRANE
densely staining structures made up 1. Plasma membrane-
of RNA; produces ribosomes - protective layer of the cell
-flexible yet sturdy barrier
*The more nucleoli present the -separates the cel’s internal
faster the multiplication and environment from the outside
division* environment
-selective barrier
-gives the size and shape of the
cell
-plays a role in cellular
communication
Layers and composition:
• Carbohydrate -
(mucopolysaccharides is the
strongest layer of the cell
membrane)
-Glycoproteins- membrane
proteins with a carbohydrate
group attached that
NUCLEAR STRUCTURES protrudes into the
❖ CENTROSOME- very small rounded extracellular fluid
bodies found on both ends of the -Glycocalyx- the “sugary
nucleus coating” made up of
-regulates the rate of cell division carbohydrate portions of the
and multiplication glycolipids and glycoproteins
-contains centriole
❖ CHROMOSOMES- long, linear • Proteins (peripheral and
chromatin materials combined with integral)- gate keepers to
protein molecules certain molecules
-contain the genes that represent all -Integral proteins- extend
the traits or inherited characteristics into or through the lipid
of an individual bilayer
-the genes are composed of -Transmembrane proteins-
segmented DNA span the entire lipid bilayer
TYPES OF TRAITS -Peripheral proteins-
❖ DOMINANT TRAIT- one which is attached to the inner or
present or evident or manifested in outer surface of the
majority of the offspring or children membrane, do not extend
in every generation through it
 • Lipids- barrier of some FACULTATIVE VS. ACTIVE TRANSPORT
substances FACULTATIVE OR ACTIVE PROCESSES
• Lipid bilayer- the most FACILITATED TRANSPORT
important part because of its Does not require energy Cell uses energy
selective permeability, made
Needs specific carrier Requires specific carrier
up of phospholipids,
proteins CHONS
cholesterol and glycolipids
Cannot move substances Even against a
• Fluid Mosaic Model- refers
against concentration concentration gradient
to the arrangement of
gradient
molecules within the
membrane
❖ OSMOSIS- movement of solvent or
water from a region of lower to
higher solute concentration
❖ DIFFUSION- movement of solute
particles from a region of higher to a
lower solute concentration

Types of gradient
❖ Concentration gradient -inequalities
in the solute concentration of 2
solutions separated by a
Membrane Permeability semipermeable membrane
❖ The cell is either permeable or ❖ Electrical charge gradient-
impermeable to certain substances differences in the net charge of the
❖ The lipid bilayer is permeable to solute
oxygen, carbon dioxide, water and
Transport in Vesicles
steroids, but impermeable to ❖ Vesicle- a small spherical sac formed
glucose. ( In order for glucose to by budding off from a membrane
enter the cell there is a need for ❖ Endocytosis- materials move into a
transmembrane proteins who acts cell in a vesicle formed from the
as channels to assist glucose and plasma membrane
ions) ❖ Exocytosis- vesicles fuse with the
Factors affecting passage of
plasma membrane, releasing their
substances contents into the extracellular fluid
❖ Degree of ionization ❖ Transcytosis- combination of
❖ Lipid solubility endocytosis and exocytosis
❖ Water solubility ❖ Phagocytosis- cell eating while
❖ Size of substance phinocytosis is cell drinking
Transport mechanisms in the
plasma membrane
CYTOPLASM
❖ Active transport
❖ Cytosol- intracellular fluid,
❖ Facultative or facilitated surrounds the organelles
❖ Passive
-site of many chemical reactions
-reactions provide the building
PASSIVE PROCESSES ACTIVE PROCESSES blocks for cell maintenance,
structure, function and growth
-Substance move Cell uses energy -most abundant in cytoplasm is
across cell water.
membranes without CHEMICAL COMPOSITION:
the input of any WATER- fixed and free state
energy; kinetic (MALE : 55-65% of the total body weight)
energy of individual (FEMALE: 45-55% of tbw)
molecules or ions (INFANTS: 70-80% of tbw)
No need for carrier Requires specific
CHONS carrier CONS
Osmosis Even against a
concentration
gradient
Solutions and their effects to the cell ❖ RIBOSOMES- translate the
❖ ISOTONIC SOLUTION- has the genetic code into polypeptide
same tonicity and osmolality as chains.
the blood -found attached to the rough
-does not affect the amount of endoplasmic reticulum or free in
water in cells the cytoplasm
-Normal rbc shape -60% RNA and 40% protein
Eg. Isotonic saline ❖ ENDOPLASMIC RETICULUM-
❖ HYPOTONIC SOLUTION- has transport of materials within the
lower tonicity and osmolality cell
than the blood ❖ ROUGH ER- presence of
-drives water into the cell ribosomes
-rbc undergoes hemolysis -Network of continuous sacs,
❖ HYPERTONIC SOLUTION- has studded with ribosomes.
greater tonicity and osmolality -manufactures processes, and
than the blood transports proteins for export
-drives water out of the cell into from cell.
the environment -continuous with nuclear
-rbc undergoes crenation envelope
-found abundantly in the
❖ CHO pancreas
-primary source of energy -connected to the membrane by
(1gm=4calories) a ribosomes-binding protein
-stored in the form of glycogen called ribophorins
for animals or starch for plants FUNCTIONS:
❖ FATS OR LIPIDS -believed as passageway of
-Serves as heat insulator and proteins manufactured by
provides tissue elasticity ribosomes
-secondary source of energy -used as means of
-stored in the form of communication
triglycerides -channel products from the
❖ CHONS outside and other parts of the
-necessary for tissue building cell
(1gm=4 calories) ❖ SMOOTH ER- absence of
-no storage form ribosomes
❖ ELECTROLYTES -involve in the synthesis of lipids,
-potassium, phosphate and carbohydrate metabolism, and
chlorine detoxification of drugs and
❖ CYTOSKELETON poisons.
-network of fibers extending -metabolizes calcium
throughout the cytoplasm FUNCTIONS:
-also forms the major -metabolizes small proteins
component of cilia and flagella -contains cellular detoxification
-Microfilaments and mechanisms
microtubules -synthesizing and secreting
-they will provide structural steroid hormones, enzymes of
support of the cell protein metabolism and
enzymes of lipid synthesis
❖ ORGANELLES -functions in cholesterol
-specialized and metabolically synthesis and breakdown, fat
active structure/little organs metabolism and detoxification of
within the cell drugs
❖ GOLGI COMPLEX- specialized
portion of ER consists of 3-20
flattened, membranous sacs
called cisternae
-modify, sort, and package
proteins and lipids made by the
 ER for transport to different - Self-replicate during times of
destinations increased cellular demand or
-temporary storage depots for before cell division
cellular secretions - Known as the “powerhouse of
-site of synthesis of large CHO the cell” that the site of:
❖ LYSOSOME- single membrane *TCA or Kreb’s cycle
bound structure *Oxidation of pyruvic acid
-contains digestive (proteolytic) *Oxidation of fatty acids, ketone
enzymes that break down body formation
cellular waste and debris and *Oxidation of amino acids
nutrients for use by the cell. *synthesis of fatty acids
-For intercellular defense *electron transport and
mechanism oxidative phosphoryltion
-autophagy and heterophagy ❖ Cytoplasmic Inclusion
-site of cellular digestion A. Vacuoles
-contains up to 40 enzymes for -temporary dumping site for
digestion cellular wastes
-acid hydrolases -storage of glycogen and fats
-active at acid pH (5) B. Inclusions
-suicidal bag of the cell -secretory inclusions
❖ PEROXISOME (enzymes, acids, proteins,
-spherical or oblong structures mucosubstances)
-smaller than lysosome C. Pigments
-production and degradation of -pigment granules (melanin,
H2O2 (hydrogen peroxide) lipofuscine, hemosiderin)
-degradation of certain fatty D. Fat droplets
acids and amino acids
-detoxify several toxic
substances such as alcohol

❖ MITOCHONDRION
-Outer layer
-Inner layer:
CRISTAE- series of folds
MATRIX- The large central fluid-
filled cavity
- Site of cellular respiration
- More prevalent in physiologically
active cells: muscles, liver and
kidneys
ENZYMOLOGY • Often the coenzyme is derived from a
-it refers to the science of enzymes to the vitamin,and one coenzyme may be
diagnosis and treatment of diseases associated withdifferent enzymes.
• e.g. NAD. pyridoxal phosphate
ENZYMES (Organic and vitamins in nature mainly
- Came from a Greek word en which mean water soluble vitamins)
in and zyme which means yeast.
- Substance that catalyzes a given ACTIVATORS
chemical reaction, cellular catalyst • These are inorganic in nature ionic
- They are biologic catalysts that causes cofactors
reactions in the body to take place • Usually metal ions
- There are 1,500 enzymes and many of • Cations of 2+ species
which catalyzes same reaction • Obligate to the enzymatic reaction
CHARACTERISTICS OF AN ENZYME • Metabolic regulators of a given
- One of the most common complicated reactionseries
type of proteins in terms of both •e.g. Mg-2, Na+I, K+1, Zn+2
structure and function (Metal ions)
- Proteins in nature; easily denatured with
varying molecular weight and masses HOLOENZYME
- Enzymes are amphoteric; contains acid • Refers to the combination of enzyme
and base and coenzyme
- Enzymes operate high rates
- Turnover number of enzymes is 5x10*6. APOENZYME
Where at this number are capable of • Enzymes without the presence of a
converting substrates (which have been cofactor
made to react with enzymes into • apoenzyme (True enzymes or the true
products proteins)+ Coenzyme = Holoenzyme
- Reactions catalyzes are frequently
reversible PROSTHETIC GROUP
- Usually it operates with assistance of a • A coenzyme that cannot be removed
non-protein cofactor called co-enzyme from its attachment with an enzyme
- Enzymes are synthesized in an inactive using dialysis.
state or zymogen state e.g. pyridoxal PO4 in transaminase
e.g. Pepsinogen+HCI= pepsin reaction
- Changes in enzyme concentration in
tissue cells reflect changes in states of METALLOENZYME
health and disease of the tissues • Inorganic activators existing as a part
of the enzyme molecule
COENZYME
• These are non-protein biochemical or SUBSTRATE
ions • Substances which are acted upon by an
• Part of the enzyme reaction enzyme and is converted into a new
• Essential to the catalytic activity as a substance
co-substrate
* Organic molecules, smaller than PRODUCT
proteins • Substances derived from a
transformed substrate
ENZYME STRUCTURE I. Oxidoreductases
•It refers to the molecular/structural • Enzymes catalyzing oxidation and
arrangement of enzyme molecule reduction reactions
• Reduction - addition of hydrogen to a
4 Existing Structures double bond
• Primary structure- refers to the • Oxidation - removal of hydrogen to
sequence of amino acids joined by cleave a double bond
peptide bonds • Older names are dehydrogenases and
• Secondary structure - conformation of oxidases
the steric arrangement or conformation * Analyze or assayed for investigation or
of the segments of polypeptide chain gives information regarding heart
• Tertiary structure - arises from the attacks and liver problems.
interactions among side chains/groups • Examples of oxidoreductases
of the polymer chain; folded structure of •Oxidases (enzymes that catalyze a
an enzyme substrate)
• Quaternary Structure - refers to the - Glucose oxidose
relationship between subunits - Cytochrome oxidase
•Dehydrogenase (removal of hydrogen
• Subunits perform specific functions ion from lactate or lactic acid)
• The secondary and tertiary structures - LDH
are the most important configurations of - Iditol DH
the enzyme because these structures - MDH
are responsible for the characteristics - Isocitrate DH
such as coiling and folding resulting to - Glucose-6-PO4 DH
conformational structure - Hydroxybutyrote DH

Active Site Oxidoreductases acts on

- Refers to the area of portion of an • Secondary alcohols
enzyme in which the substrate & • Ketones
attached with the Enzyme molecule 11 is • Alkenes
where the transformation of the • Primary amines
substrate takes place • Secondary amines
• NADH. NADPH
Classification of Enzymes • Example:
•Based on catalytic activity of an • Lactate + NAD + LDH = pyruvate +
enzyme NADH
•The International Union of
Biochemistry (IUB) enzyme
commission categorized all enzymes
into 6 classes:
- Oxidoreductases
- Transferases
• Hydrolases
• Lyases
- Isomerases
• Ligases
II. Transferases 3 groups of hydrolases
• Enzymes that move and interact group ESTERASES PEPTIDASES GLYCOSIDAS
of atoms from one molecule to another ES
(amine or PO, group) ACP LEUCINE AMYLASE
• Catalyzes the transfer of a functional AMINOPEPTI
group from one molecule to another DASE
• Gives important information about ALP TRYPSIN AMYLO-6-
liver damage GLUCOSIDA
2 major subtypes: SE
• Transaminases which catalyze the CHOLLINESTE PEPSIN GLOCOSIDE
transfer of an amino group from one RASE
molecule to another. LIPASE GALACTOSI
• Kinases which catalyze the transfer of DASE
a phosphate group from ATP to give ADP
and a phosphorylated product. IV. Lyases
• Enzymes responsible for splitting
Examples of transferases molecules (lysis)
• Aspartic aminotransferase (AST) • Catalyze the addition of a group to a
Serum glutamate oxcloacetate double bond or the removal of a group to
transominase (SGOT) / catalyzes the form a double bond in a manner that
transfer of amino acids from aspartic does not involve hydrolysis or oxidation.
acid to another substrate. • Bonds broken are
• Alanine aminotransferase (ALT) • C to C bond
Serum glutamate pyruvate transaminase • C to 0 bond
(SGPT) / catalyzes the transfer of amino • C to N bond
group from alanin to another substrate • Others
• Creatine kinase Assayed in disorders of skeletal muscles
• Gamma glutamyl transferase Examples:
• Ornithine carbamyl transferase • Aldolase
• Example: • Glutamate decarboxylase- removal of
* ATP + creatine + CK = ADP + creatine cabon dioxide from glutamate
phosphate • Tryptophan decarboxylase- removal of
carbon dioxide from tryptophan
Ill. Hydrolases • Dehydratase-removal of water
• Enzymes involved in the splitting of • Hydratase- addition of water
molecules with water as a part of the
reaction process V. Isomerases
• Catalyze a hydrolysis reaction in which -Enzymes responsible for the
the addition of a water to a bond causes conversion of one isomer to another
the bond to break. It involves the transformation from:
• Cis-trans
• L-D forms
• Aldehyde to ketone
-All reactions are reversible
-No clinical importance
Examples:
• Glucose PO4, isomerase
• Ribose PO4, isomerase
VI. Ligases • Naming of enzymes by the use of their
- Enzymes causing bond formation empirical names
between two molecules to form a longer • Example: trypsin, pepsin
molecule • Standard system of identifying
Example: enzymes
• Ligase enzyme • Formulated by IUB and IUPAC
• Amino-acyl-tRNA synthetase – (INSTITUTIONAL UNION OF PHYSICAL
activates amino acids before APPLIED CHEMISTRY)
incorporation to the polypeptide chain
Systematic name
• Describe the nature of the reactions
catalyzed
• Unique numerical code designation
(consists of 4 members separated by
periods)
• Prefixed with letter E.C. (Enzyme
Commission)
• E.C. 3.1.3.2 - ACP
• E.C.3.1.3.1- ALP
• 1ST digit - denotes the class of the
enzyme
• 2ND digit - denotes the sub-class of the
enzyme
- 3RD digit - denotes the sub-class
• 4TH digit - speciFic serial number given
to each enzyme within its sub-class
• This approach removes all ambiguity
about the enzyme's identity

Trivial names
• A.K.A non-specific, practical name,
working name
• Identical to systematic name and often
ENZYME NOMENCLATURE a simplification of it
• Each enzyme was designated a name • Suitable for everyday use
according to the reaction it catalyzes • Uses acronyms anti abbreviations
Example: oxidation of glucose - glucose • Orthophosphoric monoester
oxidase phosphorylase ( ALP)
-It is costumary to identify enzymes by
adding the suffix "ase" to the group upon
which the enzyme acts
Example: Urea - urease
Uric - uricase
Phosphate esters - phosphatase
Lipid - lipid esterase
Lactose - lactase
Starch – amylase
(• Cellulase catalyzes the hydrolysis of are specie specific
cellulose E.g. LDH of rabbits & humans
•L-amino acid oxidase catalyzes the C. ALLOENZYME
oxidation of L-amino acids •Genetically-transmitted enzyme
• Sucrase catalyzes the hydrolysis of •Important in defining the biochemical
sucrose characteristics of an individual
• Aspartate aminotransferase catalyzes •Present only in selected individuals of
the transfer of an amino group from the same specie
aspartate to a different molecule) • Practical value in forensic medicine &
Genetics
ENZYME VARIANTS
• Several distinct forms of enzymes ORIGIN OF PLASMA ENZYMES:
• Important in the diagnosis of CLASSIFICATION OF ENZYMES IN BLOOD
specificity
A. ISOENZYMES A. PLASMA-SPECIFIC ENZYMES
-Multichained enzymes 1. Generally secreted by the liver
-Enzymes of similar activity 2. Enzymes that exert their function in
-Typically appearing in specific tissue, plasma
organ & cell organelle of organisms Examples: Coagulation factors
belonging to the same specie Fibrinolytic factors
Example: Lactate Dehydrogenase (LDH) Complement system
• Contains H & M sub-units (polypeptide B. NON-PLASMA SPECIFIC ENZYMES
chains) 1. Enzymes that do not have specific
• The sub-units combine to form functions in plasma
different isoenzymes: 2. Plasma lacks activators or coenzymes
H4- LD1- heart, RBC & renal tubules w/c are necessary for enzyme activity
H3M - LD2 – heart, RBC & renal tubules 3. Two Classes;
H2M2 - LD3 - Lungs, Lymphocytes, B.1 Enzymes of Secretion
spleen, pancreas - normally secreted in plasma at a high
HM3 - LD4 - Liver, skeletal muscles rate but are rapidly disposed off to
CHARACTERISTICS of ISOENZYMES normal excretory channels
1. Charged molecules - as shown in - concentration in plasma is maintained
electrophoresis at constantly low level
2. Moblity in Ion Exchange Resin
3. Response to activation & inactivation Enzymes based on distribution
process Unilocular Enzymes
E.g. ACP (RBC) - not inactivated by • These are enzymes found only in the
2% Formalin cell sap
ACP (Prostate) - inactivated by • Found only in one location
2% Formalin Bilocular enzyme
4. Relative substrate specificities • These are enzymes that are found in
E.g. ACP (RBC) is less sensitive to the mitochondria and cell sap
a-naphthyl PO4
5. Response to Inhibitors
E.g. ACP is inhibited by fluoride,
heparin, oxalates
B. HETEROENZYME
-Enzymes of similar catalytic activity but
 to take place.
-If the catalytic activity of an
enzyme on the substrate is fast =
shorter reaction time
-The enzyme is freed & can act
again on the remaining substrate
2. SUBSTRATE CONCENTRATION - direct
relationship
• MICHAELIS-MENTEN CURVE - shows
the relationship of the reaction velocity
to the substrate concentration
•Two Phases:
a. First Order Kinetics
- Enzyme conc. is fixed; Substrate conc.
is varied
- Rate of reaction is almost directly
proportional to
substrate conc. at low values
- Rate of reaction is dependent on
substrate conc.
b. Zero Order Kinetics
- Reaction rate is unaffected by
increased substrate concentration
A. Factors that Affect Binding -Dependent on enzyme
of Enzyme to Substrate concentration
• Energy- refers to activation energy -When maximum velocity is reached,
•Molecular Compatibility the rate of increase in velocity is "O"
commonness/sameness between (Zero order reaction)
Enzyme & Substrate 3. Enzyme Concentration
• Space Availability - refers to the # of • Direct relationship
enzymes or substrates that can be • An increase in enzyme concentration
reacted results to an increase in the catalytic
•Specificity- refers to the particular activity of the enzyme
enzyme acting on a specific substrate 4. Temperature
•Optimum temperature - the
B. Factors Affecting E-S Combination temperature w/c is considered as
•Lock & Key - refers to the active site favorable for the catalytic activity of the
being complementary in shape & size enzyme (30 - 37°C or 37 - 40°CI
to the substrate •Q10 value - refers to the increased
•Induced Fit Model - the enzyme reaction rate for every 10°C increase
changes in shape during binding to (rate of reaction is doubled)
be able to accommodate the • 50 - 60°C : enzyme undergoes
substrate inactivation and denaturation
•Further increase in °T leads to loss of
C. Factors Influencing the Enzymatic enzymatic activity
Reaction • Some enzymes are stored at
1. TIME - refers to the condition when refrigerator T (2 - 8°C)
the enzymatic reaction is allowed
5. pH - Hydrogen lon Concentration system & enzyme is fully restored
•Optimum pH - the point at w/c the -Physical processes that remove
reaction rate is greatest inhibitors: dialysis, gel filtration
• At pH 7.0 - 8.0, many enzymes show b. Irreversible Inhibition
maximum activity -Inhibitors covalently combine w/ the
• Pepsin is active at 1.5 and ALP at 10.5 enzyme
-Physical methods are ineffective in
separating inhibitors from the enzymes
Examples of Inhibitors
1. Excess substrate causes competition
between substrate molecules for a
single binding site
2. Product of reaction - may itself be an
inhibitor of the forward reaction
3. E-S complex does not break to yield
products
4. Chemical substances
E.g. Fluoride, Oxalate, Heparin, Cupric
ion, Tartrate
6. Activators
• Required for full enzyme activity 8. Coenzyme concentration
• Help bind the substrate to the active • Many enzymes require a coenzyme for
site by forming ionic bridges the reaction to proceed (Vitamins,
• Help orient the substrate so it is Coenzyme A or B, NAD)
attached to the enzyme in the correct •These must be present in proper
configuration. concentration for many enzyme
reactions to take place

9. Prosthetic Group
-Coenzyme that firmly binds with the
enzyme

7. Inhibitors ENZYME DENATURATION

- Substances that decrease the rate of • Refers to the disruption of the 3-
enzyme reaction dimensional structure of the
Functions: enzyme molecule that leads to the
a. Binds to the active site, blocking loss of enzyme activity
access of the substrate to the enzyme •Denaturation may be reversed if
(Competitive Inhibition) the reaction process has not gone
b. Binds elsewhere on the too far & if the denaturing agent is
enzymetcausing change removed
in shape that interferes w/ substrate
binding (Non-competitive Inhibition) DENATURING CONDITIONS
c. Binds w/ the E-S complex; no product • Elevated temperature - beyond 50 -
formed (Uncompetitive Inhibition) 60°C; weakens the stabilizing bonds
•TYPES of INHIBITION • Extremes in pH - causes unfolding of
a. Reversible Inhibition enzyme molecule
Inhibitors are possible removed from the • Radiation
• Frothing
• Strong salt solution
• Mechanical trauma
• Time of exposure

TYPES of ENZYME SPECIFICITY

1. ABSOLUTE SPECIFICITY -when an
enzyme can act and catalyze one
unique reaction
2. GROUP SPECIFICITY - when some
enzymes act on different substrates
belonging to the group
3. STEREOISOMERIC - when an enzyme
acts only on the specific isomer coenzymes
• Thiamin - TPP (Thiomin
UNITS of MEASUREMENT pyrophosphate)
1. IU - International Unit • Riboflovin - FMN/FAD
Proposed by the Commission • Nacin - NAD/NADH
on Enzymes (IUB) • Pyridoodne - PLP (pyridoxol
-Defined as the quantity of phosphate)
enzyme that will catalyze the • Folate - THF (tetrahydrofelate)
reaction of 1 umol of substrate • B5 - CoA
per minute • Biotin - Biotin
2. Katal (system international/ • B12 - B12
common)
-a unit of enzyme activity MOST COMMON DISTURBANCES
w/c converts 1 mol of • 1. Kwashiorkor - disease resulting from
substrate per second a deficiency of dietary protein relative to
- conforms w/ the Systemè caloric intake (protein-energy
International (SI) scheme of malnutrition).
units • 2. Marasmus - results from slow
Other units: starvation caused by deficiency not only
3. Bodansky of protein but also of calories and other
4. Gutman-gutman nutrients.
5. BLB (Bessiy Loury Brock) •3. Anemia - blood condition
involving an abnormal reduction in
the number of RBCs or in theirk
hemoglobin content.
•4. Gout - caused by faulty
metabolism of uric acid produced in
the body by breakdown of proteins.
•5. Phenylketonuria (PKU) - this is due
to the absence of the enzyme
phenylalanine hydrolase which
converts phenylalanine to tyrosine.
•6. Albinism- this is due to the
absence of tyrosinase, which is
necessary for the formation of melanin.
•7. Alkaptonuria - this is due to the
absence of the homogentisic acid
oxygenase (homogentisic acid acetate
and fumarate).
•8. Tyrosinosis - this is due to the
absence of hydroxyphenylpyruvic acid
oxygenase which converts
hydroxyphenylpyruvic acid to
homogentisic acid.
a. Infants exhibit diarrhea, vomiting,
and a "cabbage- like" odor and fail to
thrive.
b. Without treatment, death from liver
failure ensues 6-8 months.
c. Treatment: diet low in tyrosine,
phenylalanine, and methionine.
BIOCHEMISTRY DIGESTION IN THE MOUTH
• Mechanical digestion in the mouth
DIGESTION o Chewing or mastication
o Food manipulated by tongue,
- Disintegration of the naturally ground by teeth, and mixed with
occurring foodstuff into absorbable saliva
forms o Forms bolus
SALIVARY DIGESTION
FACTORS IN DIGESTION • Chemical digestion in the mouth
o Hydrolysis of starch by salivary
• Primary factor amylase (ptyalin)
o The different enzymes found in o Takes place in the buccal cavity
the juices of the different portions and to a certain extent in the
of the digestive tact fundic end of the stomach
• Secondary factors o Starch & glycogen -> maltose
o Cooking – would rupture walls of • Salivary glands release saliva
starch granules from a complex o Ordinarily, just enough is secreted
form into dextrin which is simpler to keep mouth and pharynx moist
than starch. Which will den and clean
produce maltose and eventually o When food enters mouth,
glucose at a faster rate of time. secretion increases to lubricate,
o Mastication dissolve and begin chemical
o Movements of the stomach and digestion
intestines SALIVA
o Absorption from the intestines • Colorless, slightly viscid (because of
o Autodigestion the presence of mucin), opalescent
fluid
STAGES OF DIGESTION • Salivary glands:
• Salivary digestion o Parotid glands: rich in ptyalin;
• Gastric digestion watery
• Intestinal digestion o Sublingual glands: rich in mucin;
viscid
Parotid, sublingual and submandibular
gland
FACTORS INFLUENCING SALIVA SECRETION
1. Psychic factor – thought, sight, and
smell of food item
2. Chemical factor – associated with
the stimulation of taste buds by the
salt chemicals just like the
condiments used in food items.
(herbs, spices, seasoning etc.)
3. Mechanical factor – mastication and
movement
COMPOSITION OF SALIVA
Gastric Digestion
Average secretion: 1500 cc/24 hours
• Concentrated with the digestion of
• 99.42% water
proteins through the action of pepsin
• 0.58% solid
and HCl
o 2/3 = organic matter (mucin,
• Pepsinogen -> pepsin
ptyaline, urea, glucose, lactic acid…)
o 1/3 = inorganic salts (Cl-, HCO3- of • Mechanical digestion
o Mixing waves: gentle, rippling
Na, K, Ca, SO4- and PO4-
o pH: 7.0-7.3 peristaltic movements -> chyme
6.4-6.9
Functions of HCl
o Function: moisten and reduce the
foods into a consistency suitable for • Provides a suitable pH for protein
swallowing digestion by pepsin
Salivary amylase (Ptyalin) • Exerts preliminary swelling, denaturing
• Endoamylase which acts only on a-1,4 & hydrolyzing effect on proteins
glycosidic linkage • Facilitates absorption of iron
• Activators: Cl- and Br-; I- &NO3 • Activates pepsinogen
• Unstable below pH 4-5 • Causes hydrolysis of disaccharides
• Inactive by pepsin • Stimulates secretion of secretin
• Exerts germicidal action

Salivary digestion Pathological variation of HCl

• Achloroida:
Polysaccharides o Absence of free HCl
o Seen in Pernicious anemia
Lower MW, non-fermentable soluble • Achylia gastrica
dextrin o Partial or complete absence of
gastric juice
maltose o Indicates degeneration of the
gastric glands
• Hypochloridia:
o Suggestive of chronic gastritis or
gastric carcinoma
• Hyperchloridia:
 o Suggestive of peptic ulcer, GASTRIC JUICE: from gastric glands
cholecytitis 1. Parietal cell: HCl (o.17N) pH 0.87
2. Chief cells: pepsin
Gastric digestion 3. Mucous cells: mucin
3 phases of acid gastric juice secretion
Rennin (chymosin):
1. Psychic phase - stimulation of the • Milk curdling enzyme found in the
gastric juice secretion due to the smell, gastric juice of newborns
sight, taste of thought of food
2. Gastric phase- stimulation effect of
food Inhibitors of gastric secretion
• Enterogastrone = inhibits gastric
Secretagogue secretion and motility
• Urograstrone
Gastrin (from the pyloric mucosa) • Acids inhibitors
o 0.03 N HCl – slows secretion
Stimulates the gastric glands to secrete a o 0.1 N HCl – inhibits parietal cells
juice rich in HCl but poor in pepsin
Gastric juice: Composition
• Average secretion: 2-3 L/24 hours
o 99.4% water
o 0.6% solid
▪ Organic constituents: mucin,
pepsin, & small amount of
lipase
▪ Inorganic constituents: HCl, KCl
& PO4-
• Pepsin
o Principal digestive constituent of
the gastric juice
o Pepsinogen – activated by HCl;
3 intestinal phase o Autocatalytic
o Optimum activity: pH 1.5 – 2.5
Acid chyme (from stomach o An endopeptidase that acts on
peptide bonds
Duodenum (duodenal mucosa: secretin) o CHONS -> proteoses, peptones,
peptides

AMINOpeptidase & CARBOXYpeptidase

• Secretin: stimulates secretion of gastric,

pancreatic and intestinal juices and bile
 The pancreatic juice secreted into
pancreatic duct and accessory duct into the
into the small intestines.

The pancreatic duct joins common bile duct

and enters duodenum at hepatopancreatic
ampulla

There are different pancreatic juices which

will pass through the pancreatic duct and
• Mucin there is also the bile that will pass through
o Not digested by pepsin the common bile duct, this two will enter
o Protects the mucous membrane of the duodenum through the
hepatopancreatic ampulla. This is the
the stomach
o Buffers the HCl reason why we consider pancreas and bile
o Promotes absorption of Vitamin as part of intestinal digestion
B12

Intestinal Digestion
• Pancreatic juice
• Intestinal juice
• Bile

• Pancreatic juice
(important: pancreas, gallbladder and small o Clear, watery
intestines) o Volume: 500 ml/24 hours
o 98.7% water
o 1.3% solids
o Solid:
▪ 1/3 organic: (trypsin,
chymotrypsin, steapsin,
diastase, nucleolytic enzymes)
▪ 2/3 inorganic: )Na, K, Ca, HCO3,
Cl, PO4
o pH: 7.5 – 8.2 (HCO3-)
Pancreatic juice secretion: Nucleodepolymerases
• Ribonuclease & deoxyribonuclase
• vagal stimulation – secretion is rich in • Nucleic acids → mononucleotides
enzymes but less volume ribonuclease
• Secretin – stimulates the secretion of a • RNA -----------------→ H3PO4, Ribose,
fluid of high volume and HCO3- ; low in nitrogenous bases
enzymes
• Pancreozymin – secretion similar to Intestinal juice (succus Etericus)
vagal stimulation
• Combined secretion of the intestinal
Intestinal digestion pancreatic juice: glands at different portions: duodenum,
ENZYMES: jejunum & ileum
• Viscous and turbid due to mucin and
Trypsin: desquamated epithelial cells
• Endopeptidase acting on peptide linkage • Controlling hormones: secretin and
involving the carboxyl group of Arginine enterocrinin
and Lysine • Secretin is necessary in the secretion of
• pH 8-9 gastric pancreatic intestinal juices and
• Trypsinogen – activated by enterokinase bile
(intestinal juice)
Enterocrinin
Chymotrypsin: • Secreted by the intestinal mucosa;
• Activated by trypsin simulates the mucosal glands
• Endopeptidase: phenylalanine, tyrosine • Increases the volume of fluid and the
and tryptophan content of enzymes
• Has milk curdling effect
Solid constituents of the intestinal juice:
Carboxypeptidase: • Mucin, inorganic salts
• Exopeptidase: peptide linkage nearest • Enzymes
the free COOH group (pH 7.4) • Fats; cholesterol, phospholipids
• Metabolites (urea)
Pancreatic amylase (Diastase/
Amylopepsin) Carbohydrases:
• Rapid hydrolysis of starch • Maltase
• Maltose is immediately acted upon by • Lactase
the intestinal enzyme maltase • Sucrase (invertase)
• Sl is the most important locus of starch
digestion (pH 7.1) Peptidases
A. Aminopeptidase
Pancreatic lipase/ steapsin a. Exopeptidase: attacks the peptide
• Weak lipolytic enzyme linkage of the N-terminal amino
• Action is potentiated by bile acids, Ca & acid containing free amine group
certain amino acids b. Requires Mg++ or Mn++
 o cholesterol
o small amount of phospholipid
(lecithin)
o Mucin, urea, ALP
• Inorganic
o HCO3-
o Cl
o Na
o K

Bile acids

1. Cholic acid: 26 – 60%

2. Chenodeoxycholic acid: 30 – 50%
B. Tripeptidases and dipeptidases
3. Deoxycholic: 5 – 25%
a. Tripeptides
→ amino acids
Conjugated with glycine or taurine
b. Dipeptides
= glycocholic or taurocholic acid
- Requires Co++ or Mn++
( bile is recyclable, bile can be produced by
the body)
Nucleotidases (Nucleophosphatases):
• Cholecystokinin: stimulates discharge of
Nucleotides → H3PO4 & nucleosides
bile into the bowel
o Relaxation of the sphincter oddi
Nucleosidases ( Glucosidases or
• Cholagogues: substances that stimulate
phosphorylase)
flow of bile
- Purine nucleosidase
- Pyramidine nucleosidase
Liver bile Gallbladder bile
Nucleosides sugar & base
1-4% Solids: 4-17%
Bile (fel): Less viscous More viscous
Golden yellow Dark yellow-green
• Clear, golden yellow, slightly viscid fluid
pH 7-8.5 pH 5.5
• Secreted by the liver cells
• Stored in the gallbladder
Functions of bile:
o Concentration = 4-17% solids
• Activate steapsin
• pH: 7 – 8.5
• Emulsification
• volume: 500 – 700 ml/day
• Choleretics (secretion of bile by the
• solid content (1-4%)
liver)
• organic components:
• Neutralization of acid (pH > 7)
o bile acids
• Aid in absorption of fat and fat-soluble
o bile pigments
substances (hydrotropic effect)
o bilirubin
• Maintain cholesterol in solution II. Putrefaction – bacterial
decomposition of proteins under
Bile pigments anaerobic condition
Example: tryptophan → Indole +
• From the degradation of hemoglobin Skatole
- Biliverdin – formed from the III. Deamination – removal of amine
oxidation of bilirubin, responsible group from simple amino acids
for the green pigmentation of bile tp form short-chain organic acids
- Bilirubin – formed from the
reduction of biliverdin, responsible R – CH – COOH → R - CH2 - COOH
for the yellow pigmentation of l
enzymes NH2

Breakdown of hemoglobin IV. Decarboxylation – removal of

carboxyl group forming amines

R – CH – COOH → R – CH – NH2
l
NH2

DETOXIFICATION

Reactions involved:
1. Oxidation – one of the most
important means of detoxification

CH3CH2OH + O2 → CO2 + H2O

Chemical changes in the large intestines
• The semi-liquid residue which has 2. Reduction
escaped digestion and absorption are 3. Hydrolysis – some drugs used for
passed into the large intestine therapy are hydrolyzed in the body
• Intestinal microorganisms disintegrate
these organic residues into simpler Acetylsalicylic acid → Salicylic acid + Acetic
fragments acid
I. Fermentation – bacterial
degradation of carbohydrates 4. Conjugation – combination of the
under anaerobic condition toxic substance or one of its
Products: organic acids (e.g. metabolites with a compound or
lactic acid, acetic acid, formic normally in the body (whenever
acid, propionic acid and succinic oxidation becomes ineffective)
acid) a. occurs mainly in the liver
Gases (methane, CO2, H2) b. conjugating agents:
i. Acetic acid
ii. Cysteine
 iii. Glucuronic acid
iv. Glutamine
v. Glycine
vi. Methyl group CARBOHYDRATES DIGESTION AND
vii. Sulfuric acid ABSORPTION
viii. Thiosulfate
Dietary carbohydrates:
DIGESTION • Starch
• Begins in the oral cavity • Glycogen
o Salivary amylase – starch • Sucrose
▪ (lingual lipase) • Cellulose
• CHON digestion begins in the stomach • Lactose
o HCl and Pepsin • Pentosan
▪ Gastric lipase
• Digestion continues in the intestine Starch:
• Intestines: • Amylose: linear pattern of glucose
o BILE emulsifies, neutralies and linked by a- 1,4 glycosidic bonds
excretes cholesterol & bile • Amylopectin: branched polymer;
pigments glucose linked by a-1,4 glycosidic
o PANCREATIC SECRETION contains bonds with branching via a-1,6 linkage.
enzymes for attacking all the major
foodstuffs
o INTESTINAL SECRETIONS complete
the digestive process
o THE MAJOR PRODUCTS OF
DIGESTION ARE ASSIMILATED
o BACTERIA in the LI cause
putrefaction & fermentation

Starch/ glycogen
Glucose monomer (branching occurs here)
Amylopectin (in plants)
Glycogen (in animals)

A. BUCCAL CAVITY
• Mechanical action
• Chemical action
- Salivary amylase
TYPES OF AMYLASE
Alpha-amylase ▪ Monosaccharides are absorbed in
▪ Saccharogenic amylase the jejunum
▪ Breaks a-1,4 glycosidic bonds
▪ Found in GIT INDIGESTIBLE CARBOHYDRATES:
Beta-amylase ▪ Cellulose, hemicellulose and pectin
▪ Dextrinogenic amylase
▪ Breas the B-1,4 glycosidic linkage (Ll) bulk or roughage swells in water
▪ Not found in human GIT
▪ Equivalent enzyme is cellulase which Peristalsis and bowel evacuation
is found ruminants on grass-grazing
animals with large cecum
(b) Starch: 1-4 linkage of a glucose
monomers
(c) Cellulose: 1-4 linkage of B glucose
monmers

DIGESTION
B. STOMACH
▪ Wave like contraction of the muscle
fibers
▪ Little digestion occurs
▪ No carbohydrate-splitting enzymes
▪ Inactivation of salivary amylase by
pepsin
▪ Fructosan are broken down HCL
C. SMALL INTESTINES
▪ Peristalsis continues
▪ Complete chemical digestion of
carbohydrates
o Pancreatic secretion: amylase
o Intestinal secretions:
disaccharides
 ▪ It will not transport
glucose to the inside of
the cell if the receptor
sites for both glucose
and sodium ion are not
simultaneously filled.
▪ The energy is derived
from the difference in
sodium concentration
between the outside
and the inside
▪ As sodium diffuses to
the inside of the cell, it
drags the carrier and
glucose along with it,
thus providing the
energy for the
transport of glucose

ABSORPTION
▪ Pores of the mucosa through which
diffusion occurs are impermeable to Relative rate of transport of
water soluble solutes with MW monosaccharides with glucose as standard
greater than 100
o Simple diffusion: pentose • Galactose 110%
o Facilitated diffusion: involves • Glucose 100%
a carrier protein or • Fructose 43%
lipoprotein (fructose and • Mannose 19%
mannose) • Pentoses 9%
o Active transport: glucose and
galactose VEINS of the GIT
▪ A carrier transport is 1. Superior mesenteric veins
present in the brush 2. Splenic veins
border of the epithelial 3. Inferior mesenteric veins
cell ➔ Liver
▪ The carrier has a CARBOHYDRATE MALABSORPTION OF
receptor site for both DISACCHARIDE INTOLERANCE
glucose and sodium
Hereditary deficiencies of enzymes (e.g. o 130-160 mg postprandial
sucrase, maltase or lactose) b. It is the major energy source that
crosses the blood barrier
Bacterial decomposition c. If the level of glucose falls to 255, the
individual becomes stuporous,
Organic acids and gases followed by coma in 10 minutes which
becomes irreversible after 30 minutes
Flatulence and diarrhea d. Very efficient physiological and
hormonal mechanisms keep the blood
• Reducing the offending disaccharide level at 60% even in prolonged
from the diet is needed to control the starvation
condition
Metabolic pathways:

• Glucogenesis: conversion of non-

glucose hexoses into glucose
• Glycogenesis: synthesis of glycogen
from available glucose units
• Glycogenolysis: breakdown of glycogen
to yield glucose units
• Gluconeogenesis: conversoion of non-
CHO sources (e.g. amino acids) into
carbohydrate substrates
- Involves removal and transfer of
amino groups (transdeamination)
PHOSPHOrylation
Factors that lower Factors that
▪ Monosaccharides combine with a
blood glucose increase blood
phosphate radical = phosphorylated
glucose
sugar (will NOT diffuse back to the
1.
small intestines.)
glucokinase
Glucose + ATP ----------------> G-6-PO4
Hexokinase

▪ Phosphorylation serves to capture

the monosaccharides in the cells

BLOOD GLUCOSE
a. Mostly in free form, a-d-glucose with
small mount of phosphate ester and
only a trace of other hexoses
o NV: 80-100 mg/100ml of
blood
o 70-100 mg before breakfast
INTERCONVERSIONS-BETWEEN - has a much higher affinity for glucose than
MONOSACCHARIDES IN THE LIVER fructose
o Aldolase- utilizes fructose-1,6 biphosphate
-Most human tissues cannot utilize as substrate
galactose and fructose Clinical Significance: Fructose
galactose & fructose -> glucose ->blood-> o Fructosuria
other cells > lack of fructokinase
> benign and asymptomatic
(GLUCOGENESIS) >May be misinterpreted as glucosuria
oLiver cells contain all the appropriate (positive reducing sugar test)
enzymes
*cannot utilize glucose and galctose* o Fructose Intolerance
>lack of aldolase (F-1,6 biP04 cleavage)
>hypoglycemia and vomiting following
sucrose or fructose intake.
>Hypoglycemia: Fructose-1-phosphate
inhibits glycogenolysis and gluconeogenesis.
>Prolonged intake of fructose by infants:
vomiting, poor feeding, jaundice and
eventudlly hepatic failure and death

GALACTOSE METABOLISM
>galactose is obtained from milk
sugar.
>The most important organs that can
metabolize galactose are the liver
and erythrocytes

FRUCTOSE METABOLISM
oliver, kidneys, intestine and adipose
tissue can utilize the fructose as a
major source of energy
oFructokinase-phosphorylates
fructose to fructose-6-phosphate
ENZYmes:
FRUCTOSE METABOLISM
ohexokinase- phosphorylates fructose to
fructose-6-phosphate;
 Clinical Significance
oHypoglycemia:

epinephrine
>Activate phosphorylase
>Initiate glycogenolysis

Glycogen Storage Diseases

o Genetically linked metabolic disorders that
involve enzymes regulating glycogen
metabolism
GLYCOGENESIS
o Symptoms vary & may include muscle
> Liver, muscle cells: main storage (All cells of
cramps and wasting, enlarged liver, and
the body are capable of storing at least some
low BSL.
glycogen)
o Accumulation of abnormal metabolic by-
> Is the metabolic pathway by which glycogen is
products can damage the kidneys and
synthesized from glucose-6- phosphate
other organs.
> glycogen storage in normal tissues:
- 300-320 grams/day
- Glucose -> FAT (no storage limit)
2 Forms of glycogen store:
> free glycogen- one that can be readily
released
> fixed glycogen- one that can be
released slowly

GLYCOGENOLYSIS
ols the metabolic pathway by which glucose 6
phosphate is produced from glycogen
MetaboliC Pathways:
o Gluconeogenesis:
o is the metabolic pathway by which glucose
is synthesized from noncarbohydrate materials.
o Alanine + a-ketoalutarate > pyruvate
glutamate
o Aspartate + a-ketoglutarate > oxaloacetate +
glutamate

Gluconeogenesis vs Glycolysis:
o Pyruvate to glucose and glucose
o 12 compounds; 11 compounds
CARBOHYDRATES GENERAL CLASSIFICATION OF CARBOHYDRATES
-Commonly referred to as SUGARS Monosaccharides- mean 1 saccharide or 1
- CHO sugar simplest sugar or carbohydrates.
-Most abundant organic compounds in Oligosaccharides - 2 - 6 monosaccharide
nature. Disaccharides - double sugar (C12H22
O11)
-Aldehyde or ketone derivatives of Polysaccharides - most complex
polyhydric alcohol - Cellulose and Starch
POLYHYDROXY ALDEHYDES
POLYHYDROXY KETONES Monosaccharides. (Simplest)
-Substances that yield either or both of According to location of the carbonyl group
these compound when hydrolyzed.
Aldose - polyhydroxy aldehyde and the
CHARACTERISTICS OF CARBOHYDRATES carbonyl group is found at one of the
- so called because the ratio terminal sides of the hydrocarbon chain
of hydrogen to oxygen is the same as that of -aldehydes containing sugars.
water (2:1)
- in the
form of ATP

keton derivatives of polyhydric alcohols

(presence of several -OH groups)

Starch is the most abundant plant CHO Ketose - polyhydroxy ketone and the carbonyl
Glycogen is the most abundant and storage of group is found in between 2 hydrocarbon groups
animal and humans CHO > R1(CO)R2

IMPORTANCE/FUNCTIONS:
>Energy-yielding nutrients
> Structural component of living cells ( eg.
glycoproteins and proteoglycans)
> Serve as backbone or precursor substances of
some important molecules
> Some carbohydrates on the plasma
membrane mediate interactions between
cells.
> Building materials
(protein + carbohydrate = conjugated protein)

Carbonyl group: functional group of

Carbohydrates (C=O)
Saccharide: simplest structural unit of
carbohydrates
Storage forms: Starch and Glycogen
 Asymmetric Carbon: refers to the C atom
in the structure of a sugar to which 4 different
radicals are attached.

(Methane is symmetric carbon)

According to number C atoms
Diose (C2H402)
This C gives the following properties:
Triose (C3H6O3)
Optical activity/Mutarotation:
>Aldose: Glycerose
>the ability of a sugar solution to bend or
>Ketose: Dihydroxyacetone
deflect plane of polarized light.
Tetrose (C4H804)
- (d or +) DEXTROROTATORY (right)
>Erythrose
- (l or - ) LEVOROTATORY (left)
Pentose (C5H10O5)
Stereoisomerism/Enantiomerism:
> (Ald.) Arabinose, ribose, xylose
> the ability to form two sugars which are
Hexose (C6H1206)
mirror images to each other (D-isomer or
>Glucose, galactose, mannose
L-isomer).
> Fructose
Heptose (C7H14O7)
of the -OH linked to the C atom which is
(WHAT IS THE CLASSIFICATION OF RIBULOSE
the next to the terminal.
ACCORDING TO FUNCTIONAL GROUP PRESENT
>D-isomer: -OH is on the RIGHT of the C
IS A KETOSE)
atom adjacent to the terminal primary
(WHAT IS THE CLASSIFICATION OF RIBULOSE
alcohol group. (Most common for arbohydrates)
ACCORDING TO THE NUMBER OF CARBONS
>L-isomer: -OH is on the LEFT of the C
atom adjacent to the terminal primary
( WHAT IS THE CLASSIFICATION OF RIBULOSE
alcohol group. (Most common for amino acids)
ACCORDING TO THE FUNCTIONAL GROUP
PRESENT AND THE NUMBER OF CARBON
PRESENT IS A KETOPENTOSE)

EPIMERS: two sugars which differ only in the

configuration around a single C atom
IMPORTANT MONOSACCHARIDES: LACTOSE INTOLERANCE
1. Glucose (grape sugar/blood sugar/plasma - Results from deficiency of the enzyme lactase.
sugar/dextrose) NORMAL LACTOSE METABOLISM: (Small
>Most common source of cellular ATP and Intestine)
from which most complex carbohydrates
are made from
>Natural sugar mostly in the D form
> Blood conn: 80 - 100 mg/dL

2. D-Galactose
> brain sugar
>An aldohexose; Less than half as sweet as
glucose 3. Sucrose (table sugar/beet sugar/cane
>Not a natural sugar sugar)
>Has the fastest rate of absorption in the >Common table sugar; most abundant
Intestines > Natural, non-reducing disaccharide
> Also called raffinose, invertose, invert sugar
3. D-Fructose (levulose/fruit sugar) saccharide
>Sweetest sugar >Artificial sweeteners - substances with the
>A natural ketohexose; occurs in honey sweetness of sugar but w/o calories
>Serves as a source of energy for the sperm
cells Artificial sweeteners
> Liver can convert fructose to glucose a. ASPARTAME (used in softdrinks,
cereals,chewing gum, frozen snacks)
4. Mannose b. ACESULFAME K ( chewing gum, nondairy
>Naturally-occuring aldohexose creamers, diet foods)
>Not found free in nature but is widely c. SACCHARIN (diet soft drinks)
distributed in the form of polysaccharide. d. SUCRALOSE (desserts, candies, nonalcoholic
>Has a bitter taste beverages, table top sweetener)

5. Ribose POLYSACCHARIDES
> An aldopentose; component of the RNA Important properties of polysaccharides
>White, tasteless, amorphous compounds
6. Deoxyribose >X-ray analysis: crystalline
> 5 - C sugar found in DNA >No reducing property; do not form osazone
> Derived from ribose where the -OH group crystals
found in the second carbon has been >High MW; mostly are insoluble
replaced by a hydrogen >Non-fermentable by yeast
>Upon hydrolysis, yield simple sugars and sugar
DISACCHARIDES: derivatives
1. Lactose (Milk Sugar) >Polysaccharides with large MW are antigenic
> Most common CLASSIFICATION
>Least soluble and the least sweet of the 1. Storage polysaccharide: Starch and
disaccharides Glycogen
> The only non-monosaccharide which may Cellulose
be absorbed into the genital systemic and Chitin
circulation Heparin and
Hyaluronic Acid
TYPES: hot water
> HOMOPOLYSACCHARIDES - carbohydrates >Upon hydrolysis (by the action of either
with similar, repeating units acid or the enzyme INULASE) yields
Glucosans - upon hydrolysis, yield only glucose fructose
units >Clinical significance: study of renal
- (Eg. starch, glycogen, cellulose) function; inulin is easily excreted through
>Fructosans - polymerized tuctose units the kidneys when injected intravenously
Example: Inulin)
5. Dextrin
1. Starch
>It is a glucosan and can be hydrolyzed hydrolysis
into several glucose units by dilute Amorphous, white powder
inorganic acids or by mixing a solution Dextrin amylase -> maltose
of diastase -> glucose
- AMYLOSE (98%) - linear structure Uses:
a-1,4 linkages >Used as mucilage
-AMYLOPECTIN (2%) - highly branched >Used in infant feeding prevents the
chain formation of large, heavy curds or milk in
>a-1,6 linkage the baby's stomach, thus facilitating
digestion
>Found in some breakfast foods and malt
amylolytic enzyme or by acid gives rise to split Preparation
fragments with simultaneous production of
maltose TYPES:
HETEROPOLYSACCHARIDES
to glucose. In acid, however, the final product is carbohydrates which upon hydrolysis,
glucose yield sugar and sugar derivatives
-> maltose -> glucose Examples: Hyaluronic acid - yields glucoronic
Starch ->acid ->glucose acid, glucosamine and acetic acid Chondroitin
sulfate
2. Glycogen
> Storage form of carbohydrates in Hyaluronic acid
animals > Main constituent of the ground substance
> Glucose polymer stored in the liver of connective tissues
>A-1,6 linkage occurs about 8-12 glucose >Found in synovial fluid, pleural fluid,
units (24-30 units for amylopectin) vitreous humor and Wharton's jelly
> Glycogenolysis > glucose >Made of d-glucuronic acid, d-glucosamine
and acetic acid
3. Cellulose Function:
>Most abundant organic substance >Lubricant
found in nature >Cementing substance which allows passage
> Insoluble carbohydrate which is the of metabolites but not of the infective
chief structural component of plants organisms
and wood. >It is fragmented by hyaluronidase
(spreading factor), an enzyme found in
4. Inulin bacteria, sperm and in the poisonous
>Found in the bulb of onions and garlic secretions of reptiles and other animals
Function in the field of dentistry: CHEMICAL PROPERTIES OF CARBOHYDRATES
mucosa > anti-inflammatory 1. Reducing Power
and antibacterial in the Tx of -all mono and disaccharides containing the
gingivitis and periodontitis potentially free aldehyde or ketone group
possess reducing properties; reduce alkaline
accelerates healing metals and are transformed into organic acids
A. Benedict's Test
Heparin Reagent: CuSO4 in NaOH and Na Citrate
>Generated by certain types of cells lining Positive result: Reddish brown to red ppt
arterial blood vessels and by the lung
tissues B. Fehling's Test
>Powerful inhibitor of blood clotting thus Reagent: CuSO4 in NaH and Na-tartrate
preventing intravascular coagulation Positive result: Reddish brown to red ppt
>In practice, it is used to prevent clotting of (precipitate)
blood specimens (use of leech)
C. Nylander's test
PHYSICAL PROPERTIES OF CARBOHYDRATES Reagent: Bismuth subnitrate
1. Mono and disaccharides - white and Positive Result: Black colored solution
crystalline
Starches - amorphous powder D. Barfoed's test
Cellulose - fibrous Reagent: cupric acetate in weak acetic acid
2. Solubility (in ordinary solvents) - inversely Positive result: Red ppt
proportional to the complexity of their structures Use: To differentiate monosaccharides from
Disaccharides
>mono and disaccharides - more soluble in
water E. Tollen's Test
>higher CHO (e.g. starch) - insoluble; form >Tollen's reagent: 5% silver nitrate, 10% Sodium
colloidal solutions hydroxide
>Cellulose - practically insoluble >Dilute Ammonium hydroxide (7ml NH3 + 100ml
H20) + result: Formation of silver mirror
3. Mono and disaccharides - sweet Use: To differentiate aldehydes from ketones
Starches and Cellulose - tasteless
Relative sweetness of sugars: CHEMICAL PROPERTIES OF MONO &
Cane sugar (sucrose) - standard of sweetness DISACCHARIDES
Grape sugar (Fructose) - sweetest A. Bial's Orcinol-HCl test
Milk sugar (lactose) - least sweet Reagent: Bial's reagent: Orcinol in
95% Ethanol,10% FeCl3.6H20, 2 ml Orcinol-HC1
(+ 1 ml sugar solution)
Positive Result: green solution to
deep blue-green product
Use: To distinguish a pentose from a
Hexose

2. Osazone formation
>reducing sugars form characteristic osazone
crystals when heated with an excess of
phenylhydrazine(C6H5NHNH2)
>attributed to the presence of aldehyde or in samples like body fluids and can be
ketone group in their molecules used for cellulose assays
>due to this property, sugars can be identified
from a mixed sample
>Glucose, mannose and fructose have the same
configuration and thus yield the same crystals
which makes identification difficult

Oxidation of Sugars
> Aldonic acids: oxidation of the aldehyde
group of the aldose sugar to a carboxyl group
> Uronic acids: oxidation of the primary
alcohol to a carboxyl group

CHEMICAL PROPERTIES OF CARBOHYDRATES

Action of Alkali on CHO
> Moore's test: a solution containing free
aldehyde or ketose group is boiled with
btrong Na0H > brown color
(condensation)

Action of Acids
Molisch test
Reagent: Alpha-naphthol and 95%
ethvl alcohol and Conc. H,SO,
Positive Result: Violet ring at the
junction of the two liquids
Use: General test for carbohydrates

Anthrone test
Reagent: Anthrone (Keto form of q-
hydroxyanthracene or 10-
hydroanthracene-g-one) & Conc.
H2S04
Positive Result: Blue or green color
Use: for rapid detection of carbohydrates
CARBOHYDRATES DIGESTION AND ABSORPTION
Dietary carbohydrates:
- Starch
- Glycogen
- Sucrose
- Cellulose
- Lactose
- Pentosan

Starch: B. STOMACH
Amylose: linear pattern of glucose linked > Wave like contraction of the muscle fibers
by a-1,4 glycosidic bonds > Little digestion occurs
Amylopectin: branched polymer; glucose - No carbohydrate-splitting enzymes
linked by a-1,4 glycosidic bonds with branching -Inactivation of salivary amylase by
via a-1,6 linkage. pepsin
-Fructosan are broken down by HCL

C. SMALL INTESTINES
>Peristalsis continues
> Complete chemical digestion of
carbohydrates
- Pancreatic secretion: amylase
- Intestinal secretions: disaccharidases
>Monosaccharides are absorbed in the
Jejunum (lipid digestion in jejenum)

DIGESTION
A. BUCCAL CAVITY
- Mechanical Action- mastication
- Chemical Action- presence of Salivary Amylase

Types of Amylase
Alpha-amylase
> Saccharogenic amylase
> Breaks a-1,4 glycosidic bonds
> Found in human GIT

Beta-amylase
> Dextrinogenig, amylase
> Breaks the ß-1,4 glycosidic linkage
> Not found in human GIT
>Equivalent enzyme is cellulase which is
found among ruminants or grass-grazing
animals with large cecum
ABSORPTION Carbohydrate Malabserpliene Disaccharide
Pores of the mucosa through which diffusion Intolerance
occurs are impermeable to water soluble solutes Hereditary deficiencies of enzymes
with MW greater than 100 (e.g. sucrase, maltase or lactase)
- Simple Diffusion: pentose
- Facilitated Diffusion: involves a carrier protein
or lipoprotein(fructose and mannose) Bacterial decomposition
- Active Transport: glucose and galactose organic acids and gasel.
> A carrief transport is present in the brush
border of the epithelial cell.
> The carrier has a receptor site for both glucose
and sodium. flatulence and diarrhea.
> It will not transport glucose to the inside of the disaccharide
cell if the receptor sites from the diet is needed to control the
for both glucose and sodium ion are condition.
not simultaneously filled.
>The energy is derived from the difference in PHOSPHORYLATION
sodium concentration between the outside and monosaccharides combine with a
the inside. phosphate radical = phosphorylated
> As sodium diffuses to the inside of the cell, it sugar (will NOT diffuse back to the small
drags the carrier and glucose along with it, thus intestines.)
providing the energy för the transport of
glucose.
Function: phosphorylation serves to capture
the monosaccharides in the cells.

Blood Glucose
O Mostly in the free form, a-d-glucose with
small amount of phosphate ester and only trace
of other hexoses
o NV: 80-100 mg/100ml of blood
0 70-100 mg before breakfast
Relative rate of transport of monosaccharides o 130-160 mg postprandial
with glucose as standard o It is the major energy source that crosses the
o Galactose 110% blood brain barrier
o Glucose 100% o If the level of glucose falls to 25 %, the
o Fructose 43% individual becomes stuporous, followed by
o Mannose 19% coma in 10 minutes which becomes irreversible
o Pentoses 9% after 30 minutes
o Very efficient physiological and hormonal
VEINS of the GIT mechanisms keep the blood level at 60 % even
1. Superior mesenteric veins in prolonged starvation
2. Splenic veins
3. Inferior mesenteric veins
> Liver
Metabolic Pathways:
> Glucogenesis: conversion of non-glucose B. This is the final common pathway for glucose,
hexoses into glucose fatty acids and certain amino acids
>Glycogenesis: synthesis of glycogen from C. 90% of energy is derived from this pathway
available glucose units
>Glycogenolysis: breakdown of glycogen Glycolysis
to yield glucose units (glucose) > Hydrolysis of gibcose; major pathway for
>Gluconeogenesis: conversion of non- the utilization of glucose
CHO sources (e.g. amino acids) into - Anaerobic glycolysis
carbohydrate substrates (glycogen) - Aerobic glycolysis
- Intolves removal and transfer of Impt: Production of Adenosine
amino groups (transdeamination) triphosphate (ATP)

Anaerobid Glvcolysis
(Embden Meyerhof Pathway)
Stages:
1. Conversion of hexose to triose
phosphate
> Energy requiring stage
2. Conversion of triose phosphate to
pyruvate
> Energy producing stage

o Glucose becomes:
-Blood glucose (also called physiologic sugar)
-Glycogen - stored glucose
-Alpha-keto acids - part of non-essential amino -
acids
-Constituent of body structures
-Lipogenesis - produce adipose fat (from
glycerol)
-Pyruvate - key metabolite in the Kreb's cycle
o 2 Major pathways
A. Embden-Meyerhof pathway (EMP) (happens
in cytoplasm)
a. Also known as the glycolytic pathway
b.Glucose is broken down to pyruvic and lactic
acid in the absence ofoxygen (anaerobic)
B. Kreb's Cycle (Happens in mitochondria)
a. Acetyl COA (EMP)is split to carbon dioxide,
water and energy in ATP
Fate of Pyruvic Acid
> glucose-6-phospfate
> + NH3 -> alanine
> + CO2 > oxaloacetic acid
>oxidatively decarboxylated and
combine with CoA to form Acetyl CoA

Aerobic Respiration
>PYRUVATE (glycolysis) > further breakdown.
>requires oxygen; yields more energy
>two processes:
> Krebs cycle
> Electron Transport Chain and Oxidative
Phosphorylation
-Hemolytic anemia in Glucose-6-phophae
dehydrogenase necessary in production of
NADPH (metabolism in lipid)

Tricarboxylic Acid Cycle/CAC/Kreb's cycle

a. acetyl group of Acetyl CoA
b. reduced NAD (NADH) lis
c. Reduced Flavin Adenine Dinucleotide
(FADH2,)
d. Hydrogen Ion (H*)
-Pyruvate end product production of acetyl e. Guanosine Triphosphate (GTP)
enzyme fuel form.
Oxidative decarboxylation of pyruvate
>achieved by removing a CO2
molecule from pyruvate and then
removing an electron to reduce an
NAD+ into NADH
>An enzyme called coenzyme A is
combined with the remaining acetyl
to make acety| CoA

Tricarboxylic acid cycle (TCA)

o also known as the citric acid cycle, or the
Krebs cycle, after Hans Adolf Krebs who
identified the cycle.
o a series of chemical reactions of central
importance in all living cells that use
oxygen as part of cellular respiration.
o part of a metabolic pathway involved in
the chemical conversion of
carbohydrates, fats and proteins into
carbon dioxide and water to generate a
form of usable energy.
Relevance: to produce usable energy\
ELECTRON TRANSPORT CHAIN
The Electron Transport Chain and Oxidative
4 Protein Complexes: tightly bound to the
Phosphorylation
membrane:
Complex I: NADH-coenzyme Q reductase
OXIDATIVE PHOSPHORYLATION
Complex I : Succinate-coenzyme Q reductase
> process by which the energy stored in NADH
Complex Ill: Coenzyme Q-cytochrome c
and FADH2, is used to produce ATP.
reductase
Complex IV : Cytochrome c oxidase
Coenzyme Q/Ubiquinone & cytochrome c: not
tightly associated; serve as mobile -carriers that
shuttle e- between the 4 complexes

ELECTRON TRANSPORT CHAIN

-series of highly organized oxidation-reduction
enzymes
- COMMON pathway: substrates oxidized by
enzymes that use NAD+ or FAD+ as electron
acceptor cofactors

(Respiratory Chain)
A. Oxidation step: elect
NADH +H* + ½ 9?
FADH2 + ½, 02
B. Phosphorylation step
ADP + P.
> The cytochromes and the Fe-S protein
centers are one-electron carriers. NADH, FADH,
and Q are two-electron Carriers
SOURCES of ELECTRON
-linked
dehydrogenases, including:
> Isocitrate, a-ketoglutarate, and malate
dehydrogenases of the CA cycle
> Pyruvate dehydrogenase
>L-3-Hydroxyayl CoA dehydrogenase of
fatty acid oxidation
> Miscellaneous NAD+-linked dehydrogenase

-linked
dehydrogenases, including:
> Succinate dehydrogenase of the TCA cycle
>FAD-linked dehydrogenase of the a-
glycerophosphate shuttle
> Acyl CoA dehydrogenase of fatty acid
oxidation
> Miscellaneous FAD-linked dehydrogenases

OXIDATIVE PHOSPHORYLATION

released when electrons are transferred along

the electron transport chain is coupled to the
formation of ATP from ADP and Pi
(chemiosmotic phosphorylation)

Cells

may occur w/o oxidative phosphorylation

electrons is not trapped as ATP, instead

as heat.

1-nad 3 atp
1-fad 2 atp
Pentose Phosphate Pathway The non-oxidative reactions
>primarily an anabolic pathway that utilizes the > primarily designed to generate R5P (Ribose-5-
6 carbons of glucose to generate 5 carbon sugars phpsphate)
and reducing equivalents. >convert dietary 5 carbon sugars into both 6
>oxidize glucose and under certain conditions (fructose-6-phosphate) and 3 (glyceraldehyde-3-
can completely oxidize glucose to CO2 and phosphate) carbon sugars which can then be
water. utilized by the pathways of glycolysis.
>Consists of 2 irreversible oxidative reactions
followed by a series of reversible sugar-
phosphate interconversions
>No ATP is directly consumed or produced in the
cycle.

FUNCTIONS:
>Provides a major portion of the body's NADPH-
(lipid metabolism) which functions as a
biochemical reductant
>Produces ribose-5-phosphate required for the
biosynthesis of nucleotides
>Degrades glucose
>is the metabolic pathway by which glucose is *For body needs nucleotides: Ribose-5-
used to produce NADPH, ribose-5-phosphate phosphate.
and numerous other sugar phosphates. *For body need an energy: Glyceraldehyde-3-
phosphate and Fructose-6-phosphatE BECAUSE
The oxidation steps BOTH ARE FOUND IN GLYCOLYTIC PATHWAY.
>occur at the beginning of the
pathway Ways by which PPP meets cellular needs
>the reactions that generate NADPH > When ATP demand is high, the pathway
> The reactions catalyzed by glucose 6- continues to its end products, which enter
phosphate dehydrogenase and 6- glycolysis.
phosphogluconate dehydrogenase generate one >When NADPH demand is high, intermediates
mole of NADPH each for every mole of glucose-6- are recycled to G6P (glucose-6-phosphate) and
phosphate (G6P) that enters the PPP further NADPH is produced.
>When R5P demand is high, for NA and
coenzyme production, most of the non-oxidative
stage is nonfunctional, leaving R5P (Rbose-5-
phosphate) as a major product.
Nicotinamide adenine dinucleotide
Phosphate (NADPH)
>Produced mainly in the Pentose-phosphate
pathway.
> provides the reducing equivalents for
biosynthetic reactions and for oxidation
reduction involved in protection against the
toxicity of ROS (Reactive Oxygen Species).
> used for anabolic pathways, such as fatty
acid synthesis, cholesterol synthesis and fatty
acid chain elongation.
CARBOHYDRATES GENERAL CLASSIFICATION OF CARBOHYDRATES
-Commonly referred to as SUGARS • Monosaccharides- mean 1 saccharide or 1
- CHO sugar simplest sugar or carbohydrates.
-Most abundant organic compounds in • Oligosaccharides - 2 - 6 monosaccharide
nature. • Disaccharides - double sugar (C12H22
O11)
-Aldehyde or ketone derivatives of • Polysaccharides - most complex
polyhydric alcohol - Cellulose and Starch
❖ POLYHYDROXY ALDEHYDES
❖ POLYHYDROXY KETONES Monosaccharides. (Simplest)
-Substances that yield either or both of According to location of the carbonyl group
these compound when hydrolyzed.
Aldose - polyhydroxy aldehyde and the
CHARACTERISTICS OF CARBOHYDRATES carbonyl group is found at one of the
• Hydrates of carbon - so called because the ratio terminal sides of the hydrocarbon chain
of hydrogen to oxygen is the same as that of -aldehydes containing sugars.
water (2:1)
• The cheapest source of cellular fuel - in the
form of ATP
• These are chemically defined as aldehyde and
keton derivatives of polyhydric alcohols
(presence of several -OH groups)
• 1 gram of CHO gives 4 calories
• Starch is the most abundant plant CHO Ketose - polyhydroxy ketone and the carbonyl
• Glycogen is the most abundant and storage of group is found in between 2 hydrocarbon groups
animal and humans CHO > R1(CO)R2

IMPORTANCE/FUNCTIONS:
>Energy-yielding nutrients
> Structural component of living cells ( eg.
glycoproteins and proteoglycans)
> Serve as backbone or precursor substances of
some important molecules
> Some carbohydrates on the plasma
membrane mediate interactions between
cells.
> Building materials
(protein + carbohydrate = conjugated protein)

• Carbonyl group: functional group of

Carbohydrates (C=O)
• Saccharide: simplest structural unit of
carbohydrates
• Storage forms: Starch and Glycogen
 • Asymmetric Carbon: refers to the C atom
in the structure of a sugar to which 4 different
radicals are attached.

(Methane is symmetric carbon)

According to number C atoms
• Diose (C2H402)
This C gives the following properties:
• Triose (C3H6O3)
• Optical activity/Mutarotation:
>Aldose: Glycerose
>the ability of a sugar solution to bend or
>Ketose: Dihydroxyacetone
deflect plane of polarized light.
• Tetrose (C4H804)
- (d or +) DEXTROROTATORY (right)
>Erythrose
- (l or - ) LEVOROTATORY (left)
• Pentose (C5H10O5)
• Stereoisomerism/Enantiomerism:
> (Ald.) Arabinose, ribose, xylose
> the ability to form two sugars which are
• Hexose (C6H1206)
mirror images to each other (D-isomer or
>Glucose, galactose, mannose
L-isomer).
> Fructose
›The configuration is based on the location
• Heptose (C7H14O7)
of the -OH linked to the C atom which is
(WHAT IS THE CLASSIFICATION OF RIBULOSE
the next to the terminal.
ACCORDING TO FUNCTIONAL GROUP PRESENT
>D-isomer: -OH is on the RIGHT of the C
IS A KETOSE)
atom adjacent to the terminal primary
(WHAT IS THE CLASSIFICATION OF RIBULOSE
alcohol group. (Most common for arbohydrates)
ACCORDING TO THE NUMBER OF CARBONS
>L-isomer: -OH is on the LEFT of the C
PRESENT IT’S A PENTOSE)
atom adjacent to the terminal primary
( WHAT IS THE CLASSIFICATION OF RIBULOSE
alcohol group. (Most common for amino acids)
ACCORDING TO THE FUNCTIONAL GROUP
PRESENT AND THE NUMBER OF CARBON
PRESENT IS A KETOPENTOSE)

EPIMERS: two sugars which differ only in the

configuration around a single C atom
IMPORTANT MONOSACCHARIDES: LACTOSE INTOLERANCE
1. Glucose (grape sugar/blood sugar/plasma - Results from deficiency of the enzyme lactase.
sugar/dextrose) NORMAL LACTOSE METABOLISM: (Small
>Most common source of cellular ATP and Intestine)
from which most complex carbohydrates
are made from
>Natural sugar mostly in the D form
> Blood conn: 80 - 100 mg/dL

2. D-Galactose
> brain sugar
>An aldohexose; Less than half as sweet as
glucose 3. Sucrose (table sugar/beet sugar/cane
>Not a natural sugar sugar)
>Has the fastest rate of absorption in the >Common table sugar; most abundant
Intestines > Natural, non-reducing disaccharide
> Also called raffinose, invertose, invert sugar
3. D-Fructose (levulose/fruit sugar) saccharide
>Sweetest sugar >Artificial sweeteners - substances with the
>A natural ketohexose; occurs in honey sweetness of sugar but w/o calories
>Serves as a source of energy for the sperm
cells Artificial sweeteners
> Liver can convert fructose to glucose a. ASPARTAME (used in softdrinks,
cereals,chewing gum, frozen snacks)
4. Mannose b. ACESULFAME K ( chewing gum, nondairy
>Naturally-occuring aldohexose creamers, diet foods)
>Not found free in nature but is widely c. SACCHARIN (diet soft drinks)
distributed in the form of polysaccharide. d. SUCRALOSE (desserts, candies, nonalcoholic
>Has a bitter taste beverages, table top sweetener)

5. Ribose POLYSACCHARIDES
> An aldopentose; component of the RNA • Important properties of polysaccharides
>White, tasteless, amorphous compounds
6. Deoxyribose >X-ray analysis: crystalline
> 5 - C sugar found in DNA >No reducing property; do not form osazone
> Derived from ribose where the -OH group crystals
found in the second carbon has been >High MW; mostly are insoluble
replaced by a hydrogen >Non-fermentable by yeast
>Upon hydrolysis, yield simple sugars and sugar
DISACCHARIDES: derivatives
1. Lactose (Milk Sugar) >Polysaccharides with large MW are antigenic
> Most common CLASSIFICATION
>Least soluble and the least sweet of the • 1. Storage polysaccharide: Starch and
disaccharides Glycogen
> The only non-monosaccharide which may • 2. Structural polysaccharide: Cellulose
be absorbed into the genital systemic and Chitin
circulation • 3. Acidic polysaccharide: Heparin and
Hyaluronic Acid
TYPES: hot water
> HOMOPOLYSACCHARIDES - carbohydrates >Upon hydrolysis (by the action of either
with similar, repeating units acid or the enzyme INULASE) yields
Glucosans - upon hydrolysis, yield only glucose fructose
units >Clinical significance: study of renal
- (Eg. starch, glycogen, cellulose) function; inulin is easily excreted through
>Fructosans - polymerized tuctose units the kidneys when injected intravenously
Example: Inulin)
5. Dextrin
1. Starch • Intermediary products of starch
>It is a glucosan and can be hydrolyzed hydrolysis
into several glucose units by dilute Amorphous, white powder
inorganic acids or by mixing a solution • Dextrin amylase -> maltose
of diastase •Dextrin acid -> glucose
- AMYLOSE (98%) - linear structure Uses:
a-1,4 linkages >Used as mucilage
-AMYLOPECTIN (2%) - highly branched >Used in infant feeding prevents the
chain formation of large, heavy curds or milk in
>a-1,6 linkage the baby's stomach, thus facilitating
• Starch hydrolysis digestion
• Hydrolysis of starch either by the action of >Found in some breakfast foods and malt
amylolytic enzyme or by acid gives rise to split Preparation
fragments with simultaneous production of
maltose TYPES:
•In the presence of maltase, maltose is converted • HETEROPOLYSACCHARIDES
to glucose. In acid, however, the final product is carbohydrates which upon hydrolysis,
glucose yield sugar and sugar derivatives
•Starch amylase -> maltose -> glucose Examples: Hyaluronic acid - yields glucoronic
• Starch ->acid ->glucose acid, glucosamine and acetic acid Chondroitin
sulfate
2. Glycogen
> Storage form of carbohydrates in •Hyaluronic acid
animals > Main constituent of the ground substance
> Glucose polymer stored in the liver of connective tissues
>A-1,6 linkage occurs about 8-12 glucose >Found in synovial fluid, pleural fluid,
units (24-30 units for amylopectin) vitreous humor and Wharton's jelly
> Glycogenolysis > glucose >Made of d-glucuronic acid, d-glucosamine
and acetic acid
3. Cellulose Function:
>Most abundant organic substance >Lubricant
found in nature >Cementing substance which allows passage
> Insoluble carbohydrate which is the of metabolites but not of the infective
chief structural component of plants organisms
and wood. >It is fragmented by hyaluronidase
(spreading factor), an enzyme found in
4. Inulin bacteria, sperm and in the poisonous
>Found in the bulb of onions and garlic secretions of reptiles and other animals
• White, odorless, tasteless powder soluble in
Function in the field of dentistry: CHEMICAL PROPERTIES OF CARBOHYDRATES
• Oral mucosa > anti-inflammatory 1. Reducing Power
and antibacterial in the Tx of -all mono and disaccharides containing the
gingivitis and periodontitis potentially free aldehyde or ketone group
• Enhances tissue hydration and possess reducing properties; reduce alkaline
accelerates healing metals and are transformed into organic acids
A. Benedict's Test
•Heparin Reagent: CuSO4 in NaOH and Na Citrate
>Generated by certain types of cells lining Positive result: Reddish brown to red ppt
arterial blood vessels and by the lung
tissues B. Fehling's Test
>Powerful inhibitor of blood clotting thus Reagent: CuSO4 in NaH and Na-tartrate
preventing intravascular coagulation Positive result: Reddish brown to red ppt
>In practice, it is used to prevent clotting of (precipitate)
blood specimens (use of leech)
C. Nylander's test
PHYSICAL PROPERTIES OF CARBOHYDRATES Reagent: Bismuth subnitrate
1. Mono and disaccharides - white and Positive Result: Black colored solution
crystalline
Starches - amorphous powder D. Barfoed's test
Cellulose - fibrous Reagent: cupric acetate in weak acetic acid
2. Solubility (in ordinary solvents) - inversely Positive result: Red ppt
proportional to the complexity of their structures Use: To differentiate monosaccharides from
Disaccharides
>mono and disaccharides - more soluble in
water E. Tollen's Test
>higher CHO (e.g. starch) - insoluble; form >Tollen's reagent: 5% silver nitrate, 10% Sodium
colloidal solutions hydroxide
>Cellulose - practically insoluble >Dilute Ammonium hydroxide (7ml NH3 + 100ml
H20) + result: Formation of silver mirror
3. Mono and disaccharides - sweet Use: To differentiate aldehydes from ketones
Starches and Cellulose - tasteless
Relative sweetness of sugars: CHEMICAL PROPERTIES OF MONO &
Cane sugar (sucrose) - standard of sweetness DISACCHARIDES
Grape sugar (Fructose) - sweetest A. Bial's Orcinol-HCl test
Milk sugar (lactose) - least sweet • Reagent: Bial's reagent: Orcinol in
95% Ethanol,10% FeCl3.6H20, 2 ml Orcinol-HC1
(+ 1 ml sugar solution)
Positive Result: green solution to
deep blue-green product
• Use: To distinguish a pentose from a
Hexose

2. Osazone formation
>reducing sugars form characteristic osazone
crystals when heated with an excess of
phenylhydrazine(C6H5NHNH2)
>attributed to the presence of aldehyde or in samples like body fluids and can be
ketone group in their molecules used for cellulose assays
>due to this property, sugars can be identified
from a mixed sample
>Glucose, mannose and fructose have the same
configuration and thus yield the same crystals
which makes identification difficult

Oxidation of Sugars
> Aldonic acids: oxidation of the aldehyde
group of the aldose sugar to a carboxyl group
> Uronic acids: oxidation of the primary
alcohol to a carboxyl group

CHEMICAL PROPERTIES OF CARBOHYDRATES

Action of Alkali on CHO
> Moore's test: a solution containing free
aldehyde or ketose group is boiled with
btrong Na0H > brown color
(condensation)

Action of Acids
Molisch test
• Reagent: Alpha-naphthol and 95%
ethvl alcohol and Conc. H,SO,
• Positive Result: Violet ring at the
junction of the two liquids
Use: General test for carbohydrates

Anthrone test
• Reagent: Anthrone (Keto form of q-
hydroxyanthracene or 10-
hydroanthracene-g-one) & Conc.
H2S04
• Positive Result: Blue or green color
Use: for rapid detection of carbohydrates
CARBOHYDRATES DIGESTION AND ABSORPTION
Dietary carbohydrates:
- Starch
- Glycogen
- Sucrose
- Cellulose
- Lactose
- Pentosan

Starch: B. STOMACH
Amylose: linear pattern of glucose linked > Wave like contraction of the muscle fibers
by a-1,4 glycosidic bonds > Little digestion occurs
Amylopectin: branched polymer; glucose - No carbohydrate-splitting enzymes
linked by a-1,4 glycosidic bonds with branching -Inactivation of salivary amylase by
via a-1,6 linkage. pepsin
-Fructosan are broken down by HCL

C. SMALL INTESTINES
>Peristalsis continues
> Complete chemical digestion of
carbohydrates
- Pancreatic secretion: amylase
- Intestinal secretions: disaccharidases
>Monosaccharides are absorbed in the
Jejunum (lipid digestion in jejenum)

DIGESTION
A. BUCCAL CAVITY
- Mechanical Action- mastication
- Chemical Action- presence of Salivary Amylase

Types of Amylase
Alpha-amylase
> Saccharogenic amylase
> Breaks a-1,4 glycosidic bonds
> Found in human GIT

Beta-amylase
> Dextrinogenig, amylase
> Breaks the ß-1,4 glycosidic linkage
> Not found in human GIT
>Equivalent enzyme is cellulase which is
found among ruminants or grass-grazing
animals with large cecum
ABSORPTION Carbohydrate Malabserpliene Disaccharide
Pores of the mucosa through which diffusion Intolerance
occurs are impermeable to water soluble solutes Hereditary deficiencies of enzymes
with MW greater than 100 (e.g. sucrase, maltase or lactase)
- Simple Diffusion: pentose
- Facilitated Diffusion: involves a carrier protein
or lipoprotein(fructose and mannose) Bacterial decomposition
- Active Transport: glucose and galactose organic acids and gasel.
> A carrief transport is present in the brush
border of the epithelial cell.
> The carrier has a receptor site for both glucose
and sodium. flatulence and diarrhea.
> It will not transport glucose to the inside of the • Reducing the offending disaccharide
cell if the receptor sites from the diet is needed to control the
for both glucose and sodium ion are condition.
not simultaneously filled.
>The energy is derived from the difference in PHOSPHORYLATION
sodium concentration between the outside and monosaccharides combine with a
the inside. phosphate radical = phosphorylated
> As sodium diffuses to the inside of the cell, it sugar (will NOT diffuse back to the small
drags the carrier and glucose along with it, thus intestines.)
providing the energy för the transport of
glucose.
Function: phosphorylation serves to capture
the monosaccharides in the cells.

Blood Glucose
O Mostly in the free form, a-d-glucose with
small amount of phosphate ester and only trace
of other hexoses
o NV: 80-100 mg/100ml of blood
0 70-100 mg before breakfast
Relative rate of transport of monosaccharides o 130-160 mg postprandial
with glucose as standard o It is the major energy source that crosses the
o Galactose 110% blood brain barrier
o Glucose 100% o If the level of glucose falls to 25 %, the
o Fructose 43% individual becomes stuporous, followed by
o Mannose 19% coma in 10 minutes which becomes irreversible
o Pentoses 9% after 30 minutes
o Very efficient physiological and hormonal
VEINS of the GIT mechanisms keep the blood level at 60 % even
1. Superior mesenteric veins in prolonged starvation
2. Splenic veins
3. Inferior mesenteric veins
> Liver
Metabolic Pathways:
> Glucogenesis: conversion of non-glucose B. This is the final common pathway for glucose,
hexoses into glucose fatty acids and certain amino acids
>Glycogenesis: synthesis of glycogen from C. 90% of energy is derived from this pathway
available glucose units
>Glycogenolysis: breakdown of glycogen Glycolysis
to yield glucose units (glucose) > Hydrolysis of gibcose; major pathway for
>Gluconeogenesis: conversion of non- the utilization of glucose
CHO sources (e.g. amino acids) into - Anaerobic glycolysis
carbohydrate substrates (glycogen) - Aerobic glycolysis
- Intolves removal and transfer of Impt: Production of Adenosine
amino groups (transdeamination) triphosphate (ATP)

Anaerobid Glvcolysis
(Embden Meyerhof Pathway)
Stages:
1. Conversion of hexose to triose
phosphate
> Energy requiring stage
2. Conversion of triose phosphate to
pyruvate
> Energy producing stage

o Glucose becomes:
-Blood glucose (also called physiologic sugar)
-Glycogen - stored glucose
-Alpha-keto acids - part of non-essential amino -
acids
-Constituent of body structures
-Lipogenesis - produce adipose fat (from
glycerol)
-Pyruvate - key metabolite in the Kreb's cycle
o 2 Major pathways
A. Embden-Meyerhof pathway (EMP) (happens
in cytoplasm)
a. Also known as the glycolytic pathway
b.Glucose is broken down to pyruvic and lactic
acid in the absence ofoxygen (anaerobic)
B. Kreb's Cycle (Happens in mitochondria)
a. Acetyl COA (EMP)is split to carbon dioxide,
water and energy in ATP
Fate of Pyruvic Acid
> glucose-6-phospfate
> + NH3 -> alanine
> + CO2 > oxaloacetic acid
>oxidatively decarboxylated and
combine with CoA to form Acetyl CoA

Aerobic Respiration
>PYRUVATE (glycolysis) > further breakdown.
>requires oxygen; yields more energy
>two processes:
> Krebs cycle
> Electron Transport Chain and Oxidative
Phosphorylation
INTERCONVERSIONS-BETWEEN - has a much higher affinity for glucose than
MONOSACCHARIDES IN THE LIVER fructose
o Aldolase- utilizes fructose-1,6 biphosphate
-Most human tissues cannot utilize as substrate
galactose and fructose Clinical Significance: Fructose
galactose & fructose -> glucose ->blood-> o Fructosuria
other cells > lack of fructokinase
> benign and asymptomatic
(GLUCOGENESIS) >May be misinterpreted as glucosuria
oLiver cells contain all the appropriate (positive reducing sugar test)
enzymes
*cannot utilize glucose and galctose* o Fructose Intolerance
>lack of aldolase (F-1,6 biP04 cleavage)
>hypoglycemia and vomiting following
sucrose or fructose intake.
>Hypoglycemia: Fructose-1-phosphate
inhibits glycogenolysis and gluconeogenesis.
>Prolonged intake of fructose by infants:
vomiting, poor feeding, jaundice and
eventudlly hepatic failure and death

GALACTOSE METABOLISM
>galactose is obtained from milk
sugar.
>The most important organs that can
metabolize galactose are the liver
and erythrocytes

FRUCTOSE METABOLISM
oliver, kidneys, intestine and adipose
tissue can utilize the fructose as a
major source of energy
oFructokinase-phosphorylates
fructose to fructose-6-phosphate
ENZYmes:
FRUCTOSE METABOLISM
ohexokinase- phosphorylates fructose to
fructose-6-phosphate;
 Clinical Significance
oHypoglycemia:
›releaselof glucagon and
epinephrine
>Activate phosphorylase
>Initiate glycogenolysis

Glycogen Storage Diseases

o Genetically linked metabolic disorders that
involve enzymes regulating glycogen
metabolism
GLYCOGENESIS
o Symptoms vary & may include muscle
> Liver, muscle cells: main storage (All cells of
cramps and wasting, enlarged liver, and
the body are capable of storing at least some
low BSL.
glycogen)
o Accumulation of abnormal metabolic by-
> Is the metabolic pathway by which glycogen is
products can damage the kidneys and
synthesized from glucose-6- phosphate
other organs.
> glycogen storage in normal tissues:
- 300-320 grams/day
- Glucose -> FAT (no storage limit)
2 Forms of glycogen store:
> free glycogen- one that can be readily
released
> fixed glycogen- one that can be
released slowly

GLYCOGENOLYSIS
ols the metabolic pathway by which glucose 6
phosphate is produced from glycogen
MetaboliC Pathways:
o Gluconeogenesis:
o is the metabolic pathway by which glucose
is synthesized from noncarbohydrate materials.
o Alanine + a-ketoalutarate > pyruvate
glutamate
o Aspartate + a-ketoglutarate > oxaloacetate +
glutamate

Gluconeogenesis vs Glycolysis:
o Pyruvate to glucose and glucose
o 12 compounds; 11 compounds
Pentose Phosphate Pathway The non-oxidative reactions
>primarily an anabolic pathway that utilizes the > primarily designed to generate R5P (Ribose-5-
6 carbons of glucose to generate 5 carbon sugars phpsphate)
and reducing equivalents. >convert dietary 5 carbon sugars into both 6
>oxidize glucose and under certain conditions (fructose-6-phosphate) and 3 (glyceraldehyde-3-
can completely oxidize glucose to CO2 and phosphate) carbon sugars which can then be
water. utilized by the pathways of glycolysis.
>Consists of 2 irreversible oxidative reactions
followed by a series of reversible sugar-
phosphate interconversions
>No ATP is directly consumed or produced in the
cycle.

FUNCTIONS:
>Provides a major portion of the body's NADPH-
(lipid metabolism) which functions as a
biochemical reductant
>Produces ribose-5-phosphate required for the
biosynthesis of nucleotides
>Degrades glucose
>is the metabolic pathway by which glucose is *For body needs nucleotides: Ribose-5-
used to produce NADPH, ribose-5-phosphate phosphate.
and numerous other sugar phosphates. *For body need an energy: Glyceraldehyde-3-
phosphate and Fructose-6-phosphatE BECAUSE
The oxidation steps BOTH ARE FOUND IN GLYCOLYTIC PATHWAY.
>occur at the beginning of the
pathway Ways by which PPP meets cellular needs
>the reactions that generate NADPH > When ATP demand is high, the pathway
> The reactions catalyzed by glucose 6- continues to its end products, which enter
phosphate dehydrogenase and 6- glycolysis.
phosphogluconate dehydrogenase generate one >When NADPH demand is high, intermediates
mole of NADPH each for every mole of glucose-6- are recycled to G6P (glucose-6-phosphate) and
phosphate (G6P) that enters the PPP further NADPH is produced.
>When R5P demand is high, for NA and
coenzyme production, most of the non-oxidative
stage is nonfunctional, leaving R5P (Rbose-5-
phosphate) as a major product.
Nicotinamide adenine dinucleotide
Phosphate (NADPH)
>Produced mainly in the Pentose-phosphate
pathway.
> provides the reducing equivalents for
biosynthetic reactions and for oxidation
reduction involved in protection against the
toxicity of ROS (Reactive Oxygen Species).
> used for anabolic pathways, such as fatty
acid synthesis, cholesterol synthesis and fatty
acid chain elongation.
-Hemolytic anemia in Glucose-6-phophae
dehydrogenase necessary in production of
NADPH (metabolism in lipid)

Tricarboxylic Acid Cycle/CAC/Kreb's cycle

a. acetyl group of Acetyl CoA
b. reduced NAD (NADH) lis
c. Reduced Flavin Adenine Dinucleotide
(FADH2,)
KREB’S CYCLE d. Hydrogen Ion (H*)
-Pyruvate end product production of acetyl e. Guanosine Triphosphate (GTP)
enzyme fuel form.
Oxidative decarboxylation of pyruvate
>achieved by removing a CO2
molecule from pyruvate and then
removing an electron to reduce an
NAD+ into NADH
>An enzyme called coenzyme A is
combined with the remaining acetyl
to make acety| CoA

Tricarboxylic acid cycle (TCA)

o also known as the citric acid cycle, or the
Krebs cycle, after Hans Adolf Krebs who
identified the cycle.
o a series of chemical reactions of central
importance in all living cells that use
oxygen as part of cellular respiration.
o part of a metabolic pathway involved in
the chemical conversion of
carbohydrates, fats and proteins into
carbon dioxide and water to generate a
form of usable energy.
Relevance: to produce usable energy\
ELECTRON TRANSPORT CHAIN
The Electron Transport Chain and Oxidative
4 Protein Complexes: tightly bound to the
Phosphorylation
membrane:
Complex I: NADH-coenzyme Q reductase
OXIDATIVE PHOSPHORYLATION
Complex I : Succinate-coenzyme Q reductase
> process by which the energy stored in NADH
Complex Ill: Coenzyme Q-cytochrome c
and FADH2, is used to produce ATP.
reductase
Complex IV : Cytochrome c oxidase
Coenzyme Q/Ubiquinone & cytochrome c: not
tightly associated; serve as mobile -carriers that
shuttle e- between the 4 complexes

ELECTRON TRANSPORT CHAIN

-series of highly organized oxidation-reduction
enzymes
- COMMON pathway: substrates oxidized by
enzymes that use NAD+ or FAD+ as electron
acceptor cofactors

(Respiratory Chain)
A. Oxidation step: elect
NADH +H* + ½ 9?
FADH2 + ½, 02
B. Phosphorylation step
ADP + P.
> The cytochromes and the Fe-S protein
centers are one-electron carriers. NADH, FADH,
and Q are two-electron Carriers
SOURCES of ELECTRON
• NADH is derived from NAD+-linked
dehydrogenases, including:
> Isocitrate, a-ketoglutarate, and malate
dehydrogenases of the CA cycle
> Pyruvate dehydrogenase
>L-3-Hydroxyayl CoA dehydrogenase of
fatty acid oxidation
> Miscellaneous NAD+-linked dehydrogenase

• FADH, is derived from FAD-linked

dehydrogenases, including:
> Succinate dehydrogenase of the TCA cycle
>FAD-linked dehydrogenase of the a-
glycerophosphate shuttle
> Acyl CoA dehydrogenase of fatty acid
oxidation
> Miscellaneous FAD-linked dehydrogenases

OXIDATIVE PHOSPHORYLATION
• process whereby the free energy that is
released when electrons are transferred along
the electron transport chain is coupled to the
formation of ATP from ADP and Pi
(chemiosmotic phosphorylation)
• the main source of energy in aerobic
Cells
• In damaged mitochondria: respiration
may occur w/o oxidative phosphorylation
• free energy may still be released as the
electrons is not trapped as ATP, instead
as heat.

1-nad 3 atp
1-fad 2 atp
AMINO ACIDS, PEPTIDES AND PROTEINS WHERE:
*C (alpha carbon)
Proteins -Tetrahedral
- Are organic macromolecules comprising -Chiral
of amino acids as building block, needed -Asymmetric
in large amount to perform body- -Covalently linked to both an amino group and a
building and tissue repair functions. carboxyl side chain
These contain carbon, hydrogen, oxygen -Bonded to it is a H atom and a variable R group
and nitrogen, (chon) where the latter * R (side chain)
distinguish it from other -Give the amino a id its identity
macromolecules. -variable
- organic compounds of high molecular × NH2
weight made up of alpha-amino acids -Amino group
joined by means of peptide linkage -It exists as -NH3+ in neutral solutions
- most important of all biological * COOH
substances, being the fundamental -Carboxyl group
constituent of the protoplasm of the -Exist as -COO- in neutral solution
cells
- proteios" – “of first importance"
CLASSIFICATION OF AMINO ACIDS
- Proteins supply the body not only with heat 1.Non-polar amino acids
and energy, but also provide materials for -Hydrophobic amino acids
building and repair -Include all those with alkyl side chain R groups
- Proteins are "working molecules" which -Alanine
perform operational functions in living -Valine
systems (e.g. enzymes, antibodies, -Leucine
hormones, etc.) -Isoleucine
- Composed of amino acids as building blocks *Cyclic structure
-proline
AMINO ACIDS: THE BUILDING BLOCKS FOR *sulfur containing amino acids
PROTEIN -cysteine and methionine
-Is an organic compound that contains both *Aromatic amino acids
an amino (-NH2) group and a carboxyl phenyalanine and tryptophan
(-COOH) group.
-Amino acids in proteins are always the
alpha-amino acids
 sites containing one or more aspartate and
x 2. Polar, uncharged amino acids glutamate side chains
-Can form hydrogen bonds with water 4. Basic amino acids
except glycine -With net positive charge at neutral pH
-Usually more soluble in water than the non Histidine
-polar amino acids Arginine
-Good hydrogen-bond forming moieties lysine
The amide groups of asparagine and -Histidine side chains play important roles as
glutamine proton donors and acceptors in many
The hydroxyl groups of tyrosine, enzyme reactions
threonine and serine -Histidine containing peptides are important
Sulfhydryl group of cysteine biological buffers

Glycine - simplest amino acid

Has only a single hydrogen for an R group
and is not a good hydrogen
bond former

5. *other amino acids

-Occur only rarely in proteins
-Found mainly in the collagen and gelatin
proteins
Hydroxylysine
3. Acidic amino acids hydropyproline
-R groups contain a carboxyl group -Found only in a light-driven proton pumping
Aspartic acid protein call bacteriorhodopsin
Glutamic acid Pyroglutamic acid
-They have net negative charge at pH 7
-Play an important role in protein functions TYPES OF AMINO ACIDS
-Proteins that bond metal ions for structural * 1. Alpha amino acids - the amino acid
or functional purposes posses metal binding found in proteins where the amino group is
attached to the 1st carbon atom adjacent to
the carboxyl group
* 2. Beta amino acids
- this type of amino acids is names as such
because the amino group is attached to the
2nd carbon atom adjacent to the carboxyl
group
* 3. Gamma amino acids - the amino acid
where the amino group is attached to the
3rd carbon atom adjacent to the carboxy
group
Nonessential amino acids
- are those amino acids that can be
synthesized by the body and need not be
included in the diet

CHEMICAL PROPERTIES OF AMINO ACIDS

-Reactions are dependent on the numerous
different reactive groups that are present in
the same molecule
-Aliphatic monoamino monocarboxylixc
acids give all the reactions expected for
carboxyl and amino groups
-In addition, some reactions are
ESSENTIAL VS NON-ESSENTIAL characteristic of additional groups that may
Essential Amino Acids - are those amino be present
acids that cannot be synthesized by the body *Cysteine give the reactions
and are required in the diet. Since the body characteristic of the sulfhydryl (-SH) group
is not capable of synthesizing them, they *Tyrosine give the reaction
must be supplied in our diet if we are to characteristic of phenolid, group
enjoy normal health -These reactions may also be exhibited by
the protein containing these amino acids
 Folin reaction
NINHYDRIN TEST In alkaline solution, amino acids give a deep
General test for amino acids red color with sodium 1,2-naphthoquinone-
Reagent : triketohydrindene hydrate 4-sulfonate. Used for rapid quantitative
Product: CO2, ammonia and an aldehyde estimation of amino
containing one less carbon than the amino acids
acid Pauly reaction for Histidine and Tyrosine
Positive result: blue or purple color Histidine and tyrosine couple with diazotized
*proline & hydroxyproline gives yellow color sulfanilic acid in alkaline solution giving a red
*Color is produced by the ammonia group color
*Alpha amino acid + Ninhydrin=
diketohydrindylidene-diketohydrindamine PEPTIDE
+ CO, + aldehyde * Is an unbranched chain of amino acids,
each joined to the next by a peptide bond.
REACTIONS OF SPECIFIC AMINO ACIDS -since amino acids contain both amino and
Millon Reaction carbonyl groups, they combine with each
Reagent: Millon's reagent; Hg(NOg), in other to form amides, called peptides. The
HNOg W/ trace HNO2 linkage that joins them is known as a peptide
Positive result: red color linkage
Specific for : Tyrosine

Sakaguchi test
Reagent: a-naphthol and sqdium
hypochlorite
Positive result: red color
Specific for: guanidine and arginine
The product is an amide made up of two
amino acids joined together, called a
Nitroprusside test
dipeptide
Reagent: sodium nitroprusside [Na2(NO)5-
2H20] in dilute ammoniacal solution
Classification of peptides
result: red color
-If 3 amino acid units are included in a
Specific for cysteine and proteins with free
molecules, it is a tripeptide,
sulfhydryl group
-if 4 a tetrapeptide,
-if 5 a pentapeptide and so on
Aldehyde reaction
Oligopeptides - peptide chain of more than
Indole derivative gives strongly colored
12 residues and less than about 20
products with a number of aromatic
- Polypeptides are peptides containing
aldehydes. With
about 40 - 50 amino acid units in a
paradimethylaminobenzaldehyde in H2SO4,
chain
a red violet color is obtained with tryptophan
Amino acid residues
(Ehrlich reaction). This test can be used for
- units making up amino acids minus the
the quantitative estimation of tryptophan in
elements of water
proteins
Proteins - larger chains of amino acids
 -The sequence of amino acids in a chain is
numbered starting with the N-terminal
residue which is written on the left.
-The C-terminal residue is written on the
right
-Any segment of the sequence that is not
specifically known is placed in parenthesis

NOMENCLATURE OF PEPTIDES
-Named as acyl derivatives of the C-terminal
amino acid, the C-terminal unit keeping its
complete name
-The -ine ending of all but the C-terminal amino
acid is changed to -y
 state, a characteristic 3-dimensional shape
referred to as conformation (refer to the
combined 2° and 30 structure of the peptide
chain
2 major groups of proteins
Globular proteins
- named to describe the spherical shape into
which their polypeptide chains are bent and
folded as a result of tertiary structure
POLYPEPTIDES (CONT.) -Perform the operational functions in the body
-The amino acid sequence and chain length give by behaving as enzymes, hormones, antibodies
a polypeptide its biological effectiveness and transporters ( hgb and serum albumin)
-The sequence of amino acid residues is essential Fibrous proteins
for proper polypeptide function. This sequence - made up of polypeptide chains arranged in
aligns the side-chain characteristics in the proper parallel fashion along a single axis, to yield long
positions for a specific polypeptide function fibers or sheets
* Basic structural unit of connective tissues
PROTEINS: * EX. Collagen of tendons and bone matrix, a -
STRUCTURE OF PROTEINS keratin of hair, horn, nails, Elastin (elastic
Proteins contain the elements C, H, O, N and connective tissue)
usually S (and P) plus traces of Fe, Cu. I, Mn + Some proteins (e.g. myosin and fibrinogen) are
and Zn intermediate between fibrous and the globular,
Amino acids- building blocks of proteins Rod-like structures (like the fibrous) and like the
globular, they are soluble in aqueous salt
3 CATEGORIES OF PROTEIN STRUCTURE solutions
* Primary Structure
+ The sequence of amino acids which are joined * Quarternary/quaternary protein structures
together to form the polypeptide + Protein organization is produced by fitting
+ The main mode of linkage is the peptide bond together separate coiled and folded structures to
* Secondary Structure form an aggregate functional structure
+ The peptide chains are folded regularly, the + Ex. Isoenzymes (enzymes with similar but not
folding resulting from the linkage of the carbonyl identical catalytic powers)- LDH, hexokinase,
group of one peptide chain with the amine group phosphatases
of another chain by means of hydrogen bonds + Oligomeric protein - proteins with more than
+ This hydrogen bonding produces a regular one chain
coiled arrangement called Helix × Protomers - component chain
* -helix found in a-keratins that make up the hair, Ex. Hemoglobin - made up of 4 polypeptide chain
skin and nails of humans (2A and 2B), it contains 140 amino acids in each
chain
*Tertiary structure
+ The tertiary structure of the protein arises from
the interactions that take place among the side
groups of polypeptide chains, interactions which
cause bending and folding of the protein
molecule
+ Maintained by covalent disulfide bonds
+Each type of protein molecule has in its native
PROTEINS AND THEIR BIOCHEMICAL 7. Protection - when a protein from an outside
FUNCTIONS source or other substance (called antigen)
1. Structure - for animals, it is structural enters the body, the body makes its own
proteins which are the chief constituents of proteins (called antibodies) to counteract the
skin, bones, hair and fingernails foreign protein. This is the major mechanism
+ Collagen - found in bones - provides the the body used to fight diseases. Blood clotting
support for calcium to bind and form the solid is another protective device carried out by
structure of the bones proteins called fibrinogen. Without clotting, we
+ Keratin - hair and nails; it gives mechanical would bleed to death from any small wound
strength and protective covering.
8. Storage - some proteins are used to
2. Catalysis - virtually all the reactions that store materials. in the way that starch and
take place in the living organisms are catalyzed glycogen store energy. Examples are casein
by proteins called enzymes. in milk and ovalbumin in eggs, which store
The enzyme trypsin nutrients for newborn mammals and birds.
- catalyzes hydrolysis of proteins; sucrose Ferritin, a protein in the liver, stores iron.
catalyzes the hydrolysis of sucrose; and
dehydrogenase - converts ethanol to 9. Regulation - some proteins control the
acetaldehyde. Without enzymes, the reactions expression of genes are thereby regulate
would take place so slowly as to be useless. the kind of proteins manufactured in a
particular cell, and control when such
3. Movement and Contraction - every manufacture takes place
time we crook our finger, climb stairs, or
blink an eye, we use our muscles. Muscles 2 MAJOR GROUPS OF PROTEINS
expansion and contraction are involved in every A. Globular proteins
movement we make. Muscles are made up of Named to describe the spherical shape into
protein molecules called myosin and actin which their polypeptide chains are bent and
folded as a result of tertiary structure.
4. Elasticity - the protein elastin, which
possesses unique elasticity and strength, Perform the operational functions in the body
enables the skin, ligament and blood by behaving as enzymes, hormones, antibodies
vessels to stretch and rebound and transporters (hemoglobin and serum
albumin)
5. Transport - a large number of proteins
fall into this category CLASSIFICATION OF PROTEINS ON A
+Albumin - transports bilirubin, calcium, fatty NUTRITIONAL BASIS
acids, some drugs * Complete proteins
+Ferritin and transferrin - transport iron + Proteins that supply all the essential amino
+ Transcortin - cortisol (cortisol-binding acids needed by the human body for normal
protein) health
+ Hemoglobin - carries oxygen + They are derived from animal sources
+ Lipoproteins - cholesterol and triglycerides Ex: meat, fish, egg, dairy
*Incomplate proteins
6. Hormones - Many hormones are proteins + Are the proteins that are deficient in one or
among them insulin, oxytocin, human growth more essential amino acids
hormone and endomorphines +Many proteins especially those from vegetable
sources, are incomplete
Ex: veggies, nuts, seeds
For example, protein from corn (maize) is
deficient in lysine II. CONJUGATED PROTEINS- made up of
protein molecules combined with non-protein
CLASSIFICATION OF PROTEINS groups
x I. SIMPLE PROTEINS- true proteins found * Nucleoproteins- combinations of histones and
abundantly in both plants and animals. On protamines with nucleic acid
hydrolysis with enzymes, they yield a -amino - soluble in dilute solutions of NaCl and can
acids and their derivatives be extracted from the tissues by the use of
Albumins- soluble in water & dil. Neutral salt this solvent; precipitated by acidification
solution -Chromatin
- coagulated by heat & precipitated by full -Products obtained from glandular tissues
saturation with (NH4) SO4 but not with NaCl -Germ of grains
except in the presence of acid
- Members: serum albumin - blood Glycoproteins- proteins with a carbohydrate
Lactalbumin- milk component
Ovalbumin- egg white x utilized for lubricating purposes in view of their
slimy nature
Globulins- soluble in neutral dil. Salt solution Mucin- saliva
but NOT water Tendomucoid-tendons
-coagulated by heat and can be precipitated Osseomucoid-bones
from their solutions by half saturation with * - Glycoproteins are not digested by the
(NH4)2SO4 and complete saturation with NaCl enzymes of the gastro-intestinal tract, thus help
-Members: in protecting the membranes of the tract
Ovoglobulin- egg white against digestion.
Edestin-hempseed
Legumin-peas
Myosinogen-muscles
Serum globulin

Glutelins- soluble in dil. Acids and alkalies but

insoluble in neutral solvents
- Glutenin-wheat
- Oryzenin-rice

Protamines- contain small number of amino

acids
- soluble in water & dilute acids and alkalies
and are not coagulated by heat
- strongly basic; form soluble salts with strong
mineral acids
Salmin- salmon sperm
III. DERIVED PROTEINS- substances formed from
Scleroproteins (Albuminoids)- insoluble in
simple and conjugated proteins
water and neutral solvents
x A. Primary Protein derivatives- synonymous
Keratin- epidermal tissues
with denatured proteins: have undergone slight
Elastin- ligaments
intramolecular rearrangement through the
Collagen- hides, bones & cartilages
hydrolytic action of certain physical and
chemical agents
Proteans- insoluble substances resulting from
the preliminary action of water, dilute acids or * Factors Affecting Solubility:
enzymes 1. Neutral salt- low concentration of neutral
Ex. Myosan (from Myosin) salts increases the solubility of proteins (“salting
Edestan (from Edestin) in” effect) while an increase in concentration
decreases solubility ("salting out" effect).
Metaproteans- products of further hydrolysis: The solubility of any substance depends upon
soluble in weak acids and alkalies the relative affinity of solute molecules for each
Ex. Acid metaproteans (acid albuminate) other and for the solvent. Any factor which
Alkali metaproteans (alkali albuminate) decreases the interaction of solute molecules
will tend to increase solubility.
Coagulated proteins- insoluble products
resulting from either the action of heat. 2. Effect of pH- solubility is influenced by pH
alcohol, UMR or even simple mechanical because of their amphoteric nature; solubility is
shaking minimum at isoelectric point and increases with
Ex. Cooked egg albumin, cooked meat increasing acidity or alkalinity

PHYSICAL AND CHEMICAL PROPERTIES OF 3. Effect of Organic solvents

PROTEINS -When an organic solvent (which is miscible in
The number, kind and arrangement of the water-e.g. methanol, ethanol, acetone is
various amino acids within the protein molecule added to aqueous solution of proteins, it lowers
are responsible for the variety of complex the dielectric constant, so that the electrical
proteins. However, protein substances share forces between the charged particles in the
certain COMMON properties which serve to solution are increased, thus diminishing the
identify them as a distinct class of biological solubility of proteins.
substances.
- when pure, proteins are generally tasteless -Selective separation of the constituent proteins
- colorless. amorphous compounds of a mixture can be achieved by proper
- insoluble in fat solvents & present varied adjustment of pH, temperature, alcohol
degrees of solubility in water, salt solution, concentration, protein concentration and salt
dilute acids and alkalies concentration kept at low level.
-E.g. Fractionation of plasma with this
- due to high MW. form non-diffusible colloid procedure
solutions of the emulsoid type produces fractions which are of clinical
- proteins are amphoteric: they are labile. significance:
readily modified in solution when subjected Fibrin film & foam - used for surgery
to alterations in pH. UVR, heat and organic Albumin - treatment of shock, nephrosis,
solvents cirrhosis
- very reactive & highly specific due to the Globulin - passive immunization
presence of side chains & active NH2 groups Agglutinins - for blood typing

SOLUBILITY ACTION OF HEAT

* Various kinds of proteins differ markedly in -when burned, proteins decompose and liberate
their solubility: utilized for group separation and a characteristic odor of burned hair or feather
most often for purification of individual * Denaturation- the process by which solution
proteins. of proteins undergo slight intramolecular
58 to 68 egress' Celsius giving rise to changes in
chemical, physical and biologic properties
-Believed to be due to the unfolding of the
characteristic folded structure of polypeptide By salts pf Heavy metals (alkali metals)- Hg.
chain. Ag. Pb
-Reversible process: the unfolded molecule will -proteins behave like acids by virtue of the
return to its native form when conditions carboxyl radical: form insoluble salts with
become favorable (Renaturation. Refolding or alkaline metals.
Annealing) -In metallic poisoning, antidotes like egg white
- Renders the protein insoluble at isoelectric and milk are given. They form insoluble
point, causing it to precipitate (Flocculation) precipitates which can be removed subsequently
by means of a stomach tube.
Coagulation- If flocculated protein is heated
further, the clumped chains become matted By Alcohol- Maximum precipitation occurs at
together in a mass which is insoluble, not only isoelectric point (when proteins are electrically
at isoelectric point but also over the entire pH neutral). This accounts for the antiseptic
range property of alcohol.
-a process involving the linkage of adjacent * 95% alcohol has less germicidal property
protein molecules by means of side chain compared to 70% alcohol. It readily coagulates
Hydrogen bonds proteins and coagulum forms a protective
-coagulated protein is hard to dissolve & when coating on the surface of bacteria preventing
dissolved, it differs from the original protein further penetration of the alcohol.
from which it is derived: process is irreversible
Protein metabolism
Other Factors which bring about Denaturation:
-Low temperature
-high pressure
-UVR
-surface action
-mechanical shaking
+chemical agents (e.g. acids, alkalies, organic
solvents, alcohol. etc.)

PRECIPITATION
* By Acids- due to presence of the NH. group in
their molecules, amino acids have basic
properties and form insoluble salts with acids.
* Organic acids- Trichloroacetic.
Phosphomolybdic, Phosphotungstic. Picric, -Protein forms the primary constituent not only
Tannic acids are used as precipitants of the cell but also of such regulatory agents as
-Tannic acid & Picric acid are used for treating hormones and enzymes.
burns because they produce astringent effect on -It confers upon the tissue a sort of biological
the tissues, diminish secretion of mucous specificity; that is, the protein of a particular
membranes and prevent absorption of toxins. tissue is distinct and different from those of
They are also administered in some forms of other tissues.
gastro-intestinal irritation to relieve diarrhea. -This is so because complex proteins are made
Inorganic acids also precipitate protein. Nitric up of varying proportions of essential and non-
acid is used for detecting the presence of essential amino acids depending upon the
proteins in the urine tissue, organ or specie.
Heller's test)
ESSENTIAL OR INDISPENSABLE AMINO ACIDS: 2. The availability of new carbohydrate and
- Methionine lipid- influence the amount of total caloric
- Threonine requirement which must be supplied by amino
- Lysine acids
- Valine 3. The pattern of amino acid mixture supplied
- Isoleucine to
- Leucine the tissues
- Phenylalanine 4. The influence of hormones in modifying the
- Tryptophan direction and the rate of certain metabolic
- Histidine reactions
- Arginine
-The term essential and non-essential relates METABOLIC PATHWAYS OF ABSORBED AMINO
only to dietary requirements, not in relation to ACIDS
importance in metabolism. * 1. Synthesized into new tissue proteins
- The study of protein metabolism is centered including enzymes and hormones
on the metabolism of amino acids, mostly * 2. Synthesized into plasma proteins
concerned with the fate of the amino nitrogen + Liver is the site for biosynthesis of plasma
and those of the non-nitrogenous residues. proteins. albumin, globulin and fibrinogen
-The amino nitrogen enters in the formation +Synthesis is dependent upon the presence of
of urea while the non-nitrogenous residues indispensable amino acids and is increased
participate either in the carbohydrate or lipid when there is generous supply of dispensable
metabolism. AA.
3. Synthesized into liver proteins
4. Synthesized into non-protein nitrogenous
components of various cells
+Purine, pyrimidine, porphyrins, glutathione,
creatine, thyroxin, nicotinic acid, etc.
5. Decarboxylated with formation of
physiologically active amines
6. Deaminated, with the subsequent formation
of urea and oxidation of a-ketoacid or its
ABSORPTION OF AMINO ACIDS:
conversion into carbohydrate or fat
-There is rapid removal of the absorbed
7. Take part in the glucose-alanine cycle
amino acids from the blood. The amino acids
+Prevents the fluctuations in the blood glucose
are quickly disposed and appear in all tissues
level between meals
and organs of the body.
Functions
-This is evident from the fact that the amino
-To carry amino groups form skeletal muscles to
acid nitrogen level is kept more or less
the liver to be converted into urea for excretion
constant between 4-8 mg/100 ml of blood
-To provide the working muscles with blood
plasma.
glucose
made by the liver form the carbon structure of
FACTORS THAT AFFECT DISTRIBUTION OF AA IN
alanine
METABOLIC REACTIONS
* 1. Convalescing or growing individuals - for
constructions of new proteins
 2. Synthesis of Glutamine
* Glutamic acid + NH3 + ATP Mg** Glutamine +
DYNAMIC ASPECTS OF NITROGEN
ADP + Pi + H20
METABOLISM
Enzyme: glutamine synthetase
NITRQGEN BALANCE- quantitative difference
* Glutamine serves as a means of presenting to
between the nitrogen intake (from food) and the
an enzyme an unprotonated nitrogen atom at
nitrogen output (represented by nitrogen lost in
reduction level of NH3
the urine and feces)
-Glutamine serves as a store of ammonia
POSITIVE NITROGEN BALANCE- intake exceeds
3. Carbamoyl Phosphate synthesis
the output; this is found whenever new tissues
C002 + NH3 + ATP + H20 -> Carbamoy1 PO2 +
are being synthesized as in growing young,
ADP + Pi + 3 H*
convalescence, pregnancy, etc.
Enzyme: Carbamoyl phosphate synthetase
NEGATIVE NITROGEN BALANCE- output exceeds
*CarbamoyI PO4 becomes available to the cells
the intake; this is found in:
for carbamylation of amino groups as in the
1. inadequate intake of proteins as in fasting,
synthesis of citrulline from ornithine
malnutrition, diarrhea;
2. increased catabolism as in fevers, infections,
FATE OF AMMONIA:
wasting diseases; and
The ammonia liberated during the deamination
3. increased loss of body proteins as in lactation,
process is disposed off in several ways:
albuminuria
x1. It enters the general ammonia pool of the
body and may be drawn upon either for
UTILIZATION OF INORGANIC NITROGEN
anabolic or catabolic purposes. It may be used
* The only form of inorganic nitrogen, which can
in the reductive amination of keto acids derived
be utilized by living cells is ammonia.
from CHO to form
* Fixation of ammonia
new amino acids.
1. Glutamic Acid synthesis
2. Since ammonia is toxic in large
A-ketoglutaric acid + NHg + NADH + H* ->
concentrations, it is being detoxified by
Glutamic acid + NAD* + H20
synthesis to glutamine.
Enzyme: Glutamic acid dehydrogenase
3. Ammonia may be excreted directly into the
-The a-amino group of glutamic acid can be
urine.
transferred to other keto-acids by -
4. Ammonia may enter the ornithine cycle to
transamination process
form urea.
-Provides a mechanism for synthesis of other
amino acids
UREA CYCLE:
× Mammals utilize urea as the major vehicle for
excretion of surplus nitrogen (ureotelic). On the
basis of their observations. Krebs and Henseleit
proposed a cyclic mechanism for the synthesis of
urea involving the amino acids ornithine,
citrulline and arginine in the presence of the
enzyme arginase, which catalyzes the
irreversible hydrolysis of arginine to ornithine
and urea.

* 1. Nitrogen enters the urea cycle in

the form of ammonjum ion.
*2. A reaction between ammonium ion and CO, DEGRADATION OF AMINO ACIDS FOR ENERGY
produces Carbamoy| phosphate in a reaction PRODUCTION
that requires two molecules of ATP for each × Five amino acids are degraded to Acetyl CoA
molecule of carbamoyl phosphate. byway of pyruvate
3. Carbamoyl phosphate reacts with Ornithine - Alanine
to form Citrulline. (ornithine transcarbamoylase) - Threonine
* The reactions of the cycle at this point take -Glycine
place in the mitochondrion. - Serine
*Citrulline is then transported to the cytosol. -Cysteine
4. A second nitrogen enters the urea cycle when
aspartate reacts with citrulline to form *Five amino acids are degraded to acetyl COA
argininosuccinate (argilosuccinate synthase) in without forming pyruyate
another reaction that requires ATP (AMP and - Lysine
Ppi are produced in this reaction). - Tyrosine
*The amino group of the aspartate is the -Phenylalanine
source of the second nitrogen. -Tryptophan
5. Argininosuccinate is split to produce arginine -Leucine
and fumarate. (argininosuccinate Iyase)
6. Finally, arginine is hydrolyzed to give Urea × Five amino acids forming a-ketoglutarate
(arginase) and to regenerate ornithine, which is -Glutamate
transported back to the mitochondrion. -Glutamine
7. The synthesis of fumarate is a link between -Arginine
the urea cycle and the citric acid cycle. -Proline
*Fumarate is an intermediate of the citric cycle, -Histidine
and it can be converted to oxaloacetate.
*A transamination reaction can convert
oxaloacetate to aspartate, providing another
link between the two cycles
LIPIDS ordinary solvents.
>Soluble in nonpolar/organic solvents
-organic substances made up of fatty (e.g. ether, chloroform, acetone &
acids and their naturally existing benzene)
compounds and derivatives.
>Relatively insoluble in water and LIPIDS:
Diverse Functions - True waxes
TRIGLYCERIDE / Neutral FAT - Cholesterol esters
- Secondary energy source - Vitamin A esters
-Serves as a thermal insulator - Vitamin D esters
-Protects tissues from physical
Trauma 2. COMPOUND LIPIDS - contain other
radicals
CHOLESTEROL - Phospholipids - contain H3PO4 and
- Precursor of biological nitrogenous base
hormones o Lecithin - choline as nitrogenous
-Source of bile acids base
- Component of the Cell o Cephalin - ethanolamine
Membrane o Lipositol - Inositol
o Phosphatidyl serine – serine
PHOSPHOLIPIDS
-Component of the Cell Phospholipids
membrane o Plasmalogen - fatty acid group
-Associated with vital life is replaced by a fatty aldehyde
processes (e.g. CNS) (resemble lecithins &cephalins)
o Sphingomyelin - sphingosine
FIVE CATEGORIES ON THE BASIS OF and choline as nitrogenous bases
LIPID FUNCTION
o Energy storage lipids (TAG) Glycolipids - contain
o Membrane lipids (phospholipids, carbohydrate and nitrogenous
sphingoglycolipids and cholesterol) base
o Emulsification lipids (bile acids) III -defined lipids- amino lipids
o Messenger lipids (steroid hormones and and sulfo-lipids, having NH3 and
eicosanoids) SO4 groups respectively
o Protective coating lipids (biological
waxes) 3. DERIVED LIPIDS- products of hydrolysis
of I and Il: but still exhibiting the general
physical characteristics of lipids
o Saturated and unsaturated FA
o Mono and di-glyceride
o Alcohols
o Straight chain - products of hydrolysis of
waxes
Lipids: Classification • Alcohols containing the b-ionone ring –
1. SIMPLE LIPIDS- esters of fatty acids vitamin A and some carotenoids
with various alcohols. o Sterols
*Neutral fats- glycerol esters
*Waxes- esters of higher alcohols
Miscellaneous
•Aliphatic hydrocarbons - iso- octadecane from
liver
oSqualene - hydrocarbons in shark liver and
human sebum
• Carotenoids
• Vitamin D. E and K

Type of Lipid molecule Molecule

produced
upon
hydrolysis
Triacylglycerol 3 F.A. +
Examples of Fats
glycerol
•Animal fats- Oleic, palmitic and
Phosphoglyceraldehyde 2 F.A. +
stearic acids
glycerol + 1
• Mutton fat- more stearic and less
H3PO4 + I
oleic acid than pork
alcohol
• Butter fat- mainly palmitio and oleic
Sphingomyelin 1 F.A. +
acids with small amount of butyric
sphingosine
and caproic acids
+ 1 H3PO4
• Human fat- mostly oleic acid;
+ 1 alcohol
yellowish tinge is due to carotene and
Glycolipids 1 F.A. +
xanthophylls pigments
sphingosine
+ 1 CHO
FATTY ACIDS
Gangliosides 1 F.A. +
• Tail: long hydrocarbon chain
sphingosine
(hydrophobic)
+1
: 4-24 C atoms
complex CH
- Head: carboxyl (hydrophilic)

SATURATED FATTY ACIDS:

Acetic series
•General formula: CH3(CH2)n COOH
• low MW (< or = 10 C atoms)* liquid at
RT; low MP and volatile,
oThe rest are solids; high MP and non-
volatile. Those with < or = C are miscible
with H2O in all proportions
 •SOURCES
• SAT. FA: fats from animal
sources, butter, lard, coconut
oUNSAT. FA: oils mostly from plant
sources and peanut oil

*Hydroxy and Cyclic acids:

o Chaulmoogra oil: the ethyl esters
and sodium salts of Hydnocarpic and
Chaulmoogric acid are used in the
treatment of Leprosy.
oPhthioic acid: shown to produce
•UNSATURATED FATTY ACIDS: proliferation of epitheloid and giant
-the degree of unsaturation= cells; probably the agent responsible
number of double bonds for the manifestations of TB,
•Double bonds in fatty acids
usually have the cis configuration. Some important FA
• •Unstable and reactive (H2O, H2, 02, o Omega fatty acids: polyunsaturated
Br, or l2). Main source: Fish and fish oil
lower plasma triglycerides
• insoluble in ordinary solvents.
• Have beneficial effects for CHD
• liquid at RT and non-volatile.
because of their anti-thrombotic
oThe greater the degree unsaturation,
action.
the lower are the melting and
• "Brain oil" - Alzheimer's disease
congealing points
Polyunsaturated fair Acids (PUFA)
Have a carbon chain in which two or
more carbon-carbon double bonds are
present
• Omega Fatty Acids
o fish and fish oil are the most
concentrated source but maybe found
in some plants (EP. DPA, DHA)
o they lower plasma triglycerides
o they have beneficial effects on
coronary he disease because of their
thrombotic action (they reduce
platelet aggregation and blood clots)

•NOMENCLATURE: Essential FA
o SAT. FA: # of C atoms + -anoic • Linoleic, Linolenic acid and
o UNSAT. FA: # C &tors +: # of double Arachidonic acid
bonds + -enoic • Dietary deficiency
• 18 C: Ocladecanoic / Stearic -impaired growth and reproduction
: Octadecenoic / Oleic >skin disorders (e.g. eczema and dermatitis)
-excessive thirst
*kidney damage (severe cases)
Eicosanoids Group of drugs drug used for
o The biochemical derived from the fatty eicosanoid control
acid arachidonic acid • NSAID (non -steroidal anti-inflammatory
o Prostaglandins are the best known of the drugs)the oxidation of grachidonic acid to form
Eicosanoid class. Which also includes the prostagiondin ald thromboxanes
leukotrienes, prostacyclins and thromboxanes • Examples: ibuprofen. Ketoproten
o Cell membranes release arachidonic acid • COX-2 inhibitors - inhibit prostaglandin
in response to a variety of circumstances, synthesis for pain control while only minimally
including infection and allergic reactions affecting the stomach
-Drug that control leukotriene synthesis
Prostaglandins • Aspirin - prevent heart attack and strokes,
o lipids that contain 20 carbon atoms probably by blocking thromboxane synthesis
including a five membered ring structure • Cortisone - blocks the release of arachidonic
o first isolated from seminal fluid and from and therefore stops inflammation
the prostate gland (originally thought to be
the only prostaglandin, a single substance Glycerol
secreted by the male genital tract) o Simplest trihydric alcohol commonly
o Many different prostaglandins were found known as glycerine
to be present in almost all animal tissues -oily, colorless, heavy liquid with sweet
o According to one theory, aspirin kill pain Taste
by inhibiting the synthesis of -By-product in the manufacture of soap
prostaglandin [PG) - Component of fat responsible for the (+)
acrolein test (easily detected by its
They regulate a number biological activities and characteristic acrid oder)
thus exhibit hormonal behavior (e.g. known to
cause smooth muscles to contract) USES OF GLYCEROL
• A clinical use for some prostaglandins is to -Widely used both for pharmaceutical
induce labor and cosmetic preparation due to its
Prostaglandins and some of their precursors are solubility, hygroscopic nature and
also thought to cause inflammation, The anti solvent action
inflammatory, antipyretic and analgesic actions -When glycerol undergoes hydrolysis
of aspirin and other non-narcotic analgesics are under alkaline conditions, it is split into
believed to result from their ability to interfere glyceride and dihydroxyacetone
with the synthesis of prostaglandins. -it can reduce Cu++ to Cu+
The non-narcotic analgesics Inhibit the action positive for Benedict's and Fehling's test
of the enzyme prostaglandin synthetase thus
reducing the formation of excess prostaglandins -when treated with HNO3, it forms
and the pain, fever, and inflammation nitroglycerine which is used in making
dynamites and smokeless powders
• Arachidic acid oused in medicine as vasodilation drug in the
prostaglandin synthetase treatment of hypertension
PG(G2) and PG (H2) oin the body, glycerol is liberated during
(Pain causing) digestion of fat, when free glycerol is absorbed
and metabolized, it yields a caloric value
similar to glucose
General Properties of Fats 3 steric acid + glycerol
•Physical Properties
•Neutral fats
o characteristic greasy feel and penetrates
through paper producing a translucent spa
o odorless, tasteless and colorless (when pure
o color due to pigments present
o insoluble in ordinary solvents
o soluble in organic solvents (chloroform,
benzene, ether, hot alcohol)

Fats and oils

and
properties
Properties Fats Oils
Physical state Solid Liquid • Factors that contribute to the rapid onset of
Degree of High Low rancidity
saturation • Enzyme
Sources Animals Plants • Heat
• Light
Melting point High Low
• Moisture
Stability Stable Less stable •Bacteria
a Fats containing oleic acid become rancid quite
ofat floats on water because it has a lower early,
specific gravity than the latter. When shaken o To prevent rancidity in products containing
vigorously with it, fats broke up into fine unsaturated fats compounds are added to serve
particle farming a temporary emulsion. Soap, as antioxidants (eg. Vitamin e and phenols)
acacia, albumin or bile salts are used as • Rancid results in the destruction of the
emulsifying agents ( lower the surface tension) accessory foo factors lice carotene, VIt. A and
vit E. Rancid fat therefore is not any unpolatable
Chemical Properties but may even be toxic
1. Hydrolysis
o the hydrolysis of a fat molecule
generates 3 molecules of fatty acid a
glycerol molecule
o catalysts: acids, enzymes (lipases),.
superheated steam
o ex: Stearin + 3H20 + acid/enzyme ->
 ›Medical Importance:
CHOLESTEROL
o Atherosclerosis - metabolic disease that
leads to deposits of cholesterol and other
lipids (plaque) on the inner walls of the
o arteries arterial passages become
narrower, lose elasticity and the ability
to accommodate the volume of blood
pumped by the heart.

Steroids
•Derivatives of the hydrocarbon ring system
•One type of steroid found in living cells is a
STEROL, a compound in which a hydroxyl (OH)
group is attached to the steroid ring system

Cholesterol
o Most abundant sterol in anima,tissues
o Present in nerve tissue, blood and bile (the
greenish fluid secreted by the liver that aids
in the digestion of fat)
o Greek "chole" for bile and "steros" for solid
• Gallstones are nearly pure cholesterol (80 - o Plaque >inner walls of the heart to
90%) become rough rather than the normal
o In the body, cholesterol is the precursor of smooth surface > coronary thrombosis
biological steroids/steroid hormones which > heart attack due to blood clots
perform crucial body functions (e.g. bile salts, o •Cholesterol (and other lipids) must be
androgen, estrogen, etc) packaged for transport because lipid
aggregates in the aqueous bloodstream.

LIPOPROTEINS:
-Low density lipoprotein (LDLs)
-associated with deposition of "cholesterol" on
the walls of arteries.
-LDs transport cholesterol and triglycerides
from the liver to peripheral tissues.
-They enable fats and cholesterol to move
within the water-based solution of the blood
stream.
-High density lipoprotein (HDLs)
-associated with carrying "cholesterol" out of
the blood system, and is more dense/more
compact than LDL.
-HDLs act as cholesterol scavengers by
collecting cholesterol and returning it to the
liver where it produces bile salts.
o Very low density lipoproteins (VLDLs)
o A type of lipoprotein made by the liver.
o VLDLs enable fats and cholesterol to move
within the water-based solution of the
bloodstream.

Important Phosphoglycerides
-Cephalin (ethanolamine phosphoglyceride;
phosphatidyl ethanolamine)
o The A group in the formula is derived
from ethanolamine, HOCH2, CH3,NH2 (or
cholamine)
o Found in brain tissue
o Cephalin is the thromboplastic
Fat Soluble Vitamins substance which initiates the process of
o vitamin A (vision) blood coagulation
o vitamin D (Ca2 + uptake, bone Ca2+ and
phosphate) Lecithin (choline phosphoglyceride,
o vitamin E (tocopherols) (antioxidant) phosphatidyl choline)
o vitamin K (cofactor for posttranslational o has a structure in which the A residue is
modification of blood clotting proteins derived from the cation choline
formation of g-carboxyglutamate, Gla) o present in great quantities in the egg yolk,
liver and nervous tissue (arachidonic acid is one
7-dehydrocholesterol of its component fatty acid)
o Cholesterol derivative which is converted o freshly prepared lecithin is waxlike, turns
to an active form of vitamin D (Vitamin D3 brown on exposure to air; soluble in organic
or cholecalciferol) when skin is exposed to solvents and yields acrolein when heated with
sunlight dehydrating agent
• 2 fatty acids + 1 phosphoric acid + 1 glycerol +
1 choline
-When only the unsaturated acid chain (R') is
removed by hydrolysis from lecithin, a lecithin
derivative known as lysolecithin forms
Phospholipids
o Type of lipid found in all biological Lysolecithin
membranes A o Lysolecithin is a toxic substance that
o Composed of; causes destruction of RB (hemolysis).
-2 fatty acids Some snake venoms and insect poisons
- 1 glycerol are toxic because they contain enzymes
-1 phosphoric acid capable of catalyzing the hydrolysis of
-1 alcohol lecithin to lysolecithin.
o In the food industry, lecithins are used as
emulsifiers (agents that break-up mixtures of oil
and water into an emulsion of tiny drops of oils
suspended in water)
Sphingolipids
o Also found in all membranes are
particularly abundant in brain and nerve
tissue
o Sphingomyelin and glycolipids are both
classified as sphingolipids because they include
a backbone of sphingosine, an amino alcohol
o Replacing one of the amino H with a fatty
acid acyl group R-CO produces an amine of
sphingosine known as ceramide (basic
structural units for all sphingolipids

-The myelin sheath that wraps nerve fibers

Intestinal Absorption
contains phospholipids and sphingolipids.In
-Complete hydrolysis is NOT a
multiple sclerosis, lipids are lost from the
prerequisite to absorption.
sheath, which lads to nerve damage
-Fatty acid esters (resistant to
hydrolysis) are absorbed and
deposited in the fat depot. D
-Unabsorbed fats / fatty acid esters
are excreted in the feces
(STEATORRHEA)
Cerebroside
•A glycolipid found in the membranes of brain Intestinal Absorption
tissue as its name suggests -40% of ingested TG - hydrolyzed to
Ganglioside fatty acids and glycerol
•Glycolipids in which the CHO that is -3-10% - absorbed as TG: the rest are
attached to ceramide is much more partially hydrolyzed to B- monoglyceride.
complex than a monosaccharide -Glycerol (wäter-soluble)-absorbed
-Found on the outer surface of nerve via the portal route.
Cells -fatty acids (water-insoluble) are
predominantly absorbed via the
•Tay-Sach's disease (a hereditary disorder) intestinal lymph (appear in the form of
o the enzyme (hexosaminidase A) needed to triglycerides).
break down a ganglioside is deficient
leading to the accumulation of the latter in FATTY ACID MICELLE
the brain and spleen. o Consists of bile acids, free fatty
o This accumulation leads to neurological acids and Monoglycerides
deterioration, which occurs after the first •Fatty acid chains are pointed towards the
month of life and leads to death within 5 center
years. •Formation is essential for intestinal absorption
o one of many genetic disorders in lipid
metabolism that have been discovered in
humans
Triacylglycerol Storage 4. Reaction with CoA
> Adipose tissue - the only tissue in • yields Acetyl CoA and a fatty acid
which free TAGs occur in derivative of CoA which is shorter
appreciable amounts by 2C atoms (Thiolysis)
-In other types of cells and in the
bloodstream, TAGs are part of KETONES & KETOGENESIS
lipoprotein particles. - formation of ketone bodies
(normal intermediary products):
LIPID METABOLISM liver.
ACTIVATION & ENTRY of FATTY ACIDS into - Normal physiologic conditions:
the MITOCHONDRIA fatty acid degradation and
synthesis occur without
1. Activation of Fatty acids (outer significant accumulation of the
membrane) intermediates
Thiokinases: enzymes catalyzing the
formation of fatty acyl CoA esters

2. Transfer to Carnitine
-Higher fatty acids have limited ability
to cross the inner membrane
Enzyme: Fatty Acy1 COA:Carnitine fatty
acid transferase

3. Transfer to Intramitochondrial CoA

• Enzyme: Carnitine-f.a.transferase
• Fatty acyl carnitine + CoA -> Fatty acyl ChA +
Carnitine
Mitochondrial acyl thiokinase: makes possible - KETOGENIC- substances which form
the direct utilization of GTP generated in the ketone bodies
mitochondria. -Fatty acids & the following amino
acids: Isoleucine, leucine, phenylalanine &
FATTY ACID DEGRADATION tyrosine
-After the activation, the fatty acyl CoA ester - ANTIKETOGENIC
undergoes enzymatic degradation. - CHO, glycerol of fat, glucogenic amino acids
- B-Oxidation: shortening of the fatty acid chain
by 2C atoms at a time (4 successive steps)

1. Dehydrogenation with FAD

2. Reversible hydration
[3. Dehydrogenation w/ NAD
 Cholesterol
> the most important and
abundant sterol in the body
> precursor for the biosynthesis of
bile salts, steroid hormones and
vitamin D in the skin.

Absorption:
- Dietary & endogenous
phospholipids may be
absorbed as such or hydrolyzed
by lecithinase from pancreatic
juice

-Route of absorption: lymphatics.

-Its reduction products (formed through
bacterial activity) Coprosterol and
Cholestanol are poorly absorbed, and
are found abundantly in the feces.
-Cholesterol in the intestines is derived
from food, intestinal secretions and bile

• BIOSYNTHESIS OF CHOLESTEROL:
PHOSPHOGLYCERIDE SYNTHESIS (in ER) o Conversion of Acetyl CoA to Mevalonic
1. De novo synthesis in which phosphatidyl Acid
serine serves as a precursor for other -Conversion of Mevalonic acid to Squalene
phosphatides -Conversion of Squalene to Cholesterol
CDP diacyl glycerol : common precursor of
phospholipids
- Phosphatidyl serine. = P. ethanolamine
= P. choline

2. Utilization of Exogenous Choline (Salvage

pathway)
* CHOLINE - base component of
Phospholipids
• Synthesis of Lecithin

Steroids
•Compounds with the steroid nucleus
(consists of four fused carboxylic rings)
o This nucleus contains 17 carbon
atoms in one five- membered and
three six- membered rings:
Cyclopentanoperhydrophenanthrene