WhatsApp
03313067328
MISSION
M D C A T BATCH 20
26
WhatsApp
03313067328
NOISSIM
One Mission – MDCAT Success.
REGISTRATIONS
SNOITARTSIGER
What You Get:
Recorded Lectures – Access
Anytime
Past Papers & Mock Tests
Daily Quizzes & Progress
Trackingt
Smart Dashboard & 24/7 Support
Access to our Drive
REGISTRATION PROCESS:
Contact Us via the given
number for course details.
Make Payment – Payment details
will be shared when you contact us.
Send Transaction Receipt to
03313067328 (WhatsApp)
You will be added to the official
session group within 12 hours.
WhatsApp
03313067328 Team Mission MDCAT
MDCAT
MISSION
M D C A T
WhatsApp
03313067328
📢 Disclaimer (For Educational Use Only):
NOISSIM
"This content is shared strictly for educational
purposes only, under the fair use policy. We do
not own the copyright of this material. All rights
belong to the original creators, academies, or
publishers. No commercial benefit is being
taken or given from this sharing. If you are the
rightful owner and believe this violates any
copyright, please contact us directly for
immediate removal."
Under Pakistan Copyright Ordinance 1962,
limited use of copyrighted content is allowed
for non-commercial, educational purposes,
including study, research, and academic
sharing.
- MISSION MDCAT TEAM
WhatsApp
03313067328
MDCAT
WhatsApp
03313067328
Spark MDCAT Biological molecules
Chapter 1: Biological Molecules
PM&DC Syllabus
Biological molecules: Define and classifybiologicalmolecules.
Discuss the importance of biological molecules
Biological Importance of Water: Describe biologically important properties of water (polarity,
hydrolysis, specific heat, water as solvent and reagent, density, cohesion/ionization)
Carbohydrates: Discuss carbohydrates: monosaccharaides (glucose), oligosaccharides (cane sugar,
sucrose, lactose), polysaccharides (starches, cellulose, glycogen)
Proteins: Describe proteins: amino acids, structure of proteins
Lipids: Describe lipids: phospholipids, triglycerides, alcohol and esters (acylglycerol)
Ribonucleic acid (RNA): Give an account of structure and function RNA
Conjugated molecules: Discuss conjugated molecules (glycol lipids, glycol proteins)
DNA: Described in more detail chapter ‘DNA and Chromosomes’
NUMS Syllabus
a. Introduction to biological molecules d. Proteins
b. Water e. Lipids
c. Carbohydrates f. Conjugated molecules (glycolipids, glycoproteins)
IntroductiontoBiochemistry
Biological molecules are different chemical
compounds of living beings.
Biochemistry is the branch of biology which deals
with the study of chemical components and
chemical processes in living organisms.
Chemical composition of protoplasm
(BTB)
Protoplasm is the living content of the cell that is
surrounded by a plasma membrane.
It isageneraltermforcytoplasmandnucleoplasm.
Approximately 25 elements out of 92 naturally
occurring elements of earth are found in living
beings.Thesearecalled bio elements.Orbiogenic
elements. Iron (0.04%), iodine (trace)
Humanbodyiscomposedofonly16ofthesebio Proportion of various bio elements in
elements. human body.
The six commonest bio elements that constitute
99% of protoplasm are called major bioelements.
Minorbioelementsarethosethatarefoundaslessthan 1% whereas those that are found as less
than0.01%oftheprotoplasmarecalled trace elements.
They are also called dietary elements.
The survival ofanorganismdependsuponitsabilitytotake up some chemicals from its environment
and use them to chemical of its living matter.
Thebioelementsarecombinedwitheachotherandcan form thousands of different biomolecules
which may be:
1. Inorganic (water,minerals,carbondioxide,acids,basesand salts)
2. Organic (carbohydrates,lipids,proteinsandnucleicacids).
W h a t s A Proportion
pp of various biomolecules in bacterial and mammalian cells
03313067328
Spark MDCAT Biological molecules
Water Protein Carbohydrates Lipids DNA 70% 70%
RNA 15% 18%
Other organic molecules (enzymes, hormones, metabolites) 3% 4% 3%
Inorganic ions (Na+, K+, Ca++, Mg++, Cl-, SO2-4) 2% 0.25%
1% 1.1%
6% 2%
2% 1%
1%
Major forming 99% of body including C, H, O, N, Ca, P
Classification of On the basis of Minorforming 1% body e.g., S, Mg, etc.
bioelements (25) presence
Trace / dietary forming about 0.1% e,g., Zn, Mn, etc.
Macro-organic molecules
Carbohydrates are composed of C, H, O and provide fuel for the metabolic activities of the cell.
Carbohydrates are present in the cytoplasm of the cells.
(KPK)
Proteinsare the most abundant organic compounds in
protoplasm and body.
Metabolism
They have both structural and functional role in the body.
Proteins are present in the membranes, ribosomes,
cytoskeleton and enzymes of the cell. Anabolism Catabolism
Lipids are heterogenous groups of
hydrophobic
compounds. Lipids are present in the membranes and
Needs Energy is
cytoplasm of the cell energy
Nucleic acids (DNA and RNA) are most essential organic released
compounds, for living organisms. The nucleic acid DNA is
present in the chromosome. The nucleic acid RNA is present Simpler Larger
in the nucleoplasm and cytoplasm. compounds
join molecules
break
1. C-H Hydrocarbon (potential source of
bond chemical energy for cellular activities) Complex
2. C-N Peptide bond (forms proteins which are Smaller
compounds simpler
bond very important due to their diversity in are formed molecules
structure and function)
formed
3. C-O Glyosidic bond (provides stability to
Such as
bond complex carbohydrate molecules)
photo-
Such as
synthesis respiration
Metabolic reactions of cell
All the reactions taking place within a cell are collectively
referred to as metabolism.
Those reactions in which simpler substances are combined to form complex substances are called
anabolic reactions. Anabolic reactions need energy.
Energy is released by the breakdown of complex molecules into simpler ones, such reactions are
called catabolic reactions.
Note
Don't confuse involvement of water in hydrolysis withmaking a solution, in which role of water is to act
as a solvent, rather than taking part in chemical reaction.
Also do not assume that this breakdown releases energy, which is usually produced when the simpler
substances are oxidized in respiration.
Hydration is yet another completely different process, involving the addition of water but not the
breaking of bonds.
WhatsApp
03313067328
Page |2
Spark MDCAT Biological molecules
Condensation and hydrolysis
Condensation Hydrolysis
Condensation monomers
is the intocombination
polymer by of
the The hydrolysisis essentially the reverse of
removal of water. condensation i.e., the breakdown of a polymer
During condensation, a hydroxyl (OH -) group into its monomers by the addition of water.
is removed from one monomer and a During hydrolysis, an (OH-) group from water is
hydrogen (-H) is removed from the other to attached to one monomer and (H) is attached
make water and as a result a bond is to the other monomer. All digestion reactions
are example of hydrolysis.
synthesized between the
monomers.
Condensation is also called dehydration
synthesis.
Condensation does not take place unless the Actually, all digestion reactions are examples of
proper enzyme is present, and the monomers hydrolysis, which are controlled by enzymes
are in an activated energy-rich form. such as carbohydrases, proteases, lipases,
Condensation and hydrolysis
Importance of Water
Water is the most abundant compound inall organisms and forms three fourth of the body in humans.
It varies from 65 to 89 percent (FTB = 70%, BTB & KPK = 70 to 90%) in different organisms.
Human tissues contain about 20 percent water in bone cells and 85 percent (FTB = 85 to 90%) in brain
cells.
Seeds also contain 20% water.
contains 88% water.
Cucumber contains 98% water.
Jelly fish has exceptionally large amount of water i.e. 99% that’s why its body shows transparency.
It is also used as raw material for photosynthesis.
(KPK)
Water is essential for existence of protoplasm because protoplasm can't survive if its water content is
reduced as low as 10%.
Water dissolves all minerals present in soil which are absorbed by plant roots and transported
to other tissues
Solvent properties
Due to its polarity, water is an excellent solventfor polarsubstances and hence called universal
solvent.
Ionic substances when dissolved in water, dissociate into positive and negative ions.
Non-ionic substances having charged groups in their molecules are dispersed in water.
It is because of this property of water that almost all reactions in cells occur in aqueous media.
Nonpolar organic molecules, such as fats, are insoluble in water and help to maintain membranes
which make compartments in the cell.
Hydrogen bonding
The polarity of water molecules makes them interact with each other.
The charged regions oneach molecule are attracted to oppositely charged regions on neighbouring
molecules, forming weak bonds.
Sincethe positively chargedregion in this special type of bond is always an H atom, the bond is called
a hydrogen bond.
WhatsApp
Thisbond is often representedby a dotted line because a hydrogen bond is easily broken.
03313067328
Page |3
Spark MDCAT Biological molecules
The presenceof hydrogen bonds among water molecules causes it to remain in liquid state rather than
change to iceor steam.
(KPK)
Withouthydrogen bonds, water would boilat -80 degree Celsius
and freeze at -100 degree Celsius.
Hydrogen bonds are weaker than covalentbonds but still cause
water molecules to remain attached together.
Cohesionand adhesion
Cohesion is the intermolecular attraction between similar
molecules while adhesion is the attraction between dissimilar
molecules. Cohesion is the attraction among the water molecules which enables the water molecules
to stick together and flow together. Water molecules also have attraction to polar surfaces. This
attraction is called adhesion.
Both cohesion and adhesion are due to hydrogen bonds Hydrogen Bonding between
among water molecules. water molecules
These properties of water enable it to act as transport medium.
Water can fill tubular vessel and still flows so that dissolved molecules are evenly distributed
throughout the system
Hydrophobicexclusion
Hydrophobicexclusion can be defined as reduction of the contact area between water and hydrophobic
substanceswhich are placed in water.
Biologically,hydrophobic exclusion plays key roles in maintaining the integrity of lipid bilayer
membranes.
Hydrophobic Exclusion
High specific heat capacity
Water has great ability of absorbing heat with minimum of change in its own temperature due to its
high specific heat capacity.
The specific heat capacity of water i.e. the number of calories required to raise the temperature of 1g
of water from 15 to 16 degree C is 1.0 calorie (or 4.18 joules) which is relatively high.
Reason of high specific heat is that much of the energy is used to break hydrogen bonds.
Water thus works as temperature stabilizer for organisms in the environment and hence protects living
material against sudden thermal changes due to this property.
Due to this property, hot water cools slowly while cool water gets hot slowly.
High heat of vapourization
WWater
h a t s absorbs
App much heat as it changes from liquid to gas due to its high heat of vapourization.
03313067328
Page | 4
Spark MDCAT Biological molecules
Heat of vaporization is expressed as caloriesabsorbed per gram vaporized. The specific heat of
vaporizationofwater is 574 kcal/kg.
This propertyplays an important role in the regulation of heat produced by oxidation.
It also providescooling effect to plants when water is transpired, or to animals when water is
perspired.
This is highheatof vapourization of water that gives animals an efficient way to release excess body
heat in ahotenvironment.
Evaporationofonly two ml out of one litre of water lowers the temperature of the remaining 998 ml
by 1 degreeC.
Ionizationofwater
The dissociation of a molecule into ions is called ionization.
When water molecule ionizes, it releases an equal number of positive hydrogen and negative hydroxyl
ions.
This reaction is reversible but an equilibrium is maintained.
At 25 degree C the concentration of each of H+ and OH - ions in pure
water is about 10-7 mole/litre.
The H+ and OH - ions effect and take part in many chemical reactions
that occur in the cells.
Lower densityof ice
Ice floats on water. This is because ice is less dense than water.
Water is the only substance whose solid form is less dense than
liquid.
The reason of less density is that ice has a giant structure and show
maximum number of hydrogen bonding among water molecules; Lattice like arrangement of
hence, they are arranged like a lattice. ice.
(KPK)
During wintersice forms a layer at the top of ponds an lakes.
The ice layer at surface acts as an insulator to prevent water below it from freezing thus preventing
living organisms from freezing.
↓↓
Water expands at low temperature
Water has a unique property, as it expands (density ) when temperature falls below 4 °C.
Water is most heavy at 4 °C
Water body freezes on the surface at low temperature.
Protection
Water is an effective lubricant that provides protection against the damage resulting from friction.
For example, tears protect the surface of eye from the rubbing of eyelids.
Water also forms a fluid cushion around organs that helps to protect them from trauma.
For example, pleural fluid around lungs, pericardial fluid around heart, CSF around brain.
Carboh ydrates
Carbohydrates are the most abundant biomolecule in nature.
The word carbohydrate literally means hydrated carbons.
They are composed of carbon, hydrogen and oxygen and the ratio of hydrogen and oxygen is the
same as in water i.e. 2:1.
Their general formula is Cx(H2O)y where x is the whole number from three to many thousands whereas
y may be the same or different whole number.
Chemically, carbohydrates are defined as “polyhydroxy aldehydes or ketones, or complex
substances which on hydrolysis yield polyhydroxy aldehyde or ketone subunits.”
(BTB)
The chemistry of carbohydrate is determined by aldehyde and ketone group e.g. aldehyde is very
easily oxidized and hence are powerful reducing agent.
The C-H bonds in the carbohydrate molecules are broken down during respiration and the stored
Wenergy
h a t s Ain
p pthese bonds is released which is made available to the cells for performing various functions.
03313067328
Page | 5
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
WhatsApp
03313067328
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
WhatsApp
03313067328
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
WhatsApp
03313067328
