Introduction

Living systems are made up of various complex biomolecules such as

carbohydrates. proteins. enzymes. lipids, vitamins. hormones. nucleic
acids and compounds for storage and inchange of energy such as
ATP. etc. These biomolecules interact with each other and most of the
biochemical reactions take place in dilute solutions (pH 7 ) at body

temperature (37°C) and at 1 pressure. The structure and

atmospheric
functions of biomolecules inside the living being is studied in

biochenmistry.

CARBOHYDRATES
Hydrates of carbon having general formula, C,(H,O), is known carbohydrates.
as

For example. glucose (CH,0) fits into the general formula, C(H,O)
not considered as
But all the compounds having general formula C,(H,O), are
fits into this general
carbohydrates. For example, Ethanoic acid (CHCOOH)
but it is not a carbohydrate. Also, all carbohydrates do
not
formula, C(H,O)2,
fit into the general formula C(H,O), e.g., rhamnose (CH,20). Chemically
or ketones
carbohydrates are defined as optically active polyhydroxy aldehydes
or the compounds which produce such
units on hydrolysis. Carbohydrates are
which are sweet to
also known as saccharides. Some of the carbohydrates
taste, are also called sugars.

Classification of Carbohydrates :
can be divided
On the basis of their behaviour upon hydrolysis, carbohydrates
intothree main groups
into
) Monosaccharides : A carbohydrate which cannot be hydrolyzed
ketone is called
simpler unit of polyhydroxy aldehyde
or

are known to ocCur in

monosaccharide. About 20 monosaccharides
nature. e.g., glucose, fructose, ribose, etc.
) Oligosaccharides : A carbohydrate which upon hydrolysis yields 2-10 unit of monosaccharide is
oligosaccharide. They are further classified as disaccharides, trisaccharides, etc., depending upon the nun
aride s allky
of monosaccharides, they provide on hydrolysis. For example, sucrose is a urmte
disaccharide which on hydrk
vields two unit of monosaccharides i.e., glucose and fructose whereas raffinose is a trisaccharide
which .
ysk
hydrolysis yields three unit of monosaccharides ie.. glucose, fructose and galactose.
(i) Polysaccharides A
high molecular mass carbohydrate which upon
hydrolysis yields a large numbe
monosaccharide units is called polysaccharide e.g., starch, cellulose, glycogen, gums, etc.

(CHO,), + nH,O
nCHO,
Starch or Cellulose Glucose

Sugar and non-sugars : In general monosaccharides and oligosaccharides, are crystalline solids, soluble in
wate and sweet to taste, are collectively known as sugars. The polysaccharides, on the other
hand, ar
amorphous insoluble in water and tasteless, are known as non-sugars.

Reducing and non-reducing carbohydrates The carbohydrates containing free aldehydic (-C-H) o
ketonic (C =
0) group
reduce Fehling's solution and Tollen's reagent are known
can as
reducing
carbohydrates. All monosacchanides whether aldose or ketose are reducing in nature.

The carbohydrates in which the reducing parts are not free cannot reduce Fehling's solution and Tollen's reagent
are known as non-reducing carbohydrates.

For example, in sucrose reducing part of glucose is bonded with the reducing part of fructose. So this
disaccharide is non-reducing. All disaccharides except sucrose are reducing in nature.

All polysaccharides like starch, cellulose, glycogen etc. are non-reducing carbohydrates.

Monosaccharides
fa monosaccharide contains an aldehyde group, it is known as an aldose and if it contains keto
a group,it
is known as a ketose.

Different types of Monosaccharides

Sr. Carbon- General Aldehyde Ketone
No. atoms terms

3 Triose Aldotriose Ketotriose

e.g, Glyceraldehyde e.g., Dihydroxyacetone
2.
Tetrose Aldotetrose Ketotetrose
e.g., Erythrose e.g., Erythrulose
3. 5
Pentose Aldopentose
e.g., Arabinose
Ketopentose
e.g., Ribulose
Hexose Aldohexose
e.g., Glucose
Kétohexose
e.g., Fructose
5. 7
Heptose Aldoheptose
6.g., Sedophetolose Ketoheptose
e.g., Sedoheptulose
Glucose (Dextrose; Grape Sugar)
in the combined forms. It is present
in sweet fruits and noney.
Glucose OcCurs in nature in free as well as

Ripe grapes contain-20% of glucose.

Preparation of Glucose

is boiled with dilute HCI or H,SO, in alcoholic solution,

1. From Sucrose (Cane Sugar): When sucrose

glucose and fructose are obtained in equimolar proportion.

C,HO, + H,O CH,0, CHO

Glucose Fructose
Sucrose

2. From Starch: When starch is boiled with dilute H,SO

at 393 K under pressure, glucose is obtained.
method for the preparation of glucose.
This is the commerCa

H nCHO
(CHp),+ nH,O 393 K; 2-3 bar
Starch or
Glucose
Cellulose

Structure of Glucose
cellulose etc. It is
Glucose is an aldohexose and is the
monomer of many larger carbohydrates like starch,
on the Earth.
the most abundant organic compound

Its structure has been determined on the basis offollowing observations

detemination its molecular
1. Molecular Formula: On the basis of elemental analysis and molecular weight
formula is found to be eH,2

Carbon Chain: Glucose on prolonged heating with Hl forms n-hexane,

2. Presence of Straight Six
atoms in glucose are linked linearly.
suggesting that all six carbon
to give monoxime and adds
Presence of Carbonyl Group
Glucose reacts with hydroxylamine (NH,OH)
3.
a cyanohydrin.
a molecule of HCN to give

CHO CH N-OH

NHOH Monoxime of Glucose

(CHOH) (CHOH)
(1 eq.)
CHOH CHOH

CN
CHO CHK
OH
HCN
(CHOH) (CHOH) Cyanohydrin of glucose
(1 eq.)
CHOH CHOH

These reactions confirm the presence of a carbonyl group (C = O) in glucose.

 4. Presence of C O as an Aldehydic Group Glucose gets oxidised to monocarboxylic acid Gluconis Ba

acid upon oxidation with mild-oxidising agents like Bromin water, Tollen's reagent, Fehling's solution ete

CHO CoOH

Br,-Water
(CHOH), (CHOH) Gluconic acid

CH,OH CH,OH

This confirms the presence of an aldehydic group in glucose.

5. Presence of Five Hydroxyl Group : Acetylation of glucose with acetic anhydride gives stable pentacetate
of glucose.

CHO CHO
5(CH,CO),o
(Acetic anhydride)
(CHOH), (CH-0-C-CH)
O

CH,OH CH-O-C-CH,
This confirms the presence of five -OH groups attached to different carbon atoms in glucose.
6. Presence of Primary Alcoholic (CH,2 - OH) Group : On oxidation with nitric acid, glucose as well as
gluconic acid both yield the dicarboxylic acid, saccharic acid.

CHO COOH COOH

(CHOH)
HNO HNO
(CHOH) (CHOH).

CH,OH COOH CH,OH

Glucose Saccharic acid Gluconic acid

7. Spatial Arrangement of -OH Groups: The exact spatial arrangement of 5- OH groups in glucose was
provided by Fischer after studying many other properties of it. The configuration of open chain structure
ofglucose can be represented by Fischer projection formula as

CHO
- OH
H

HO- -H

H -OH

H- OH

CH,OH
D(+)-Glucose
Glucose is corectly named as D(+) - Glucose. 'D' before the name of glucose represents the configuration

whereas+ represents dextrorotatory nature ofthe molecule. It should be noted that there is no direct
relation between D, L configurations with d and I or (+) or (-) notations.
 Limitations of Open Chain Structure of Glucose
The open chain structure of glucose explains most of the properties of glucose except following ones

1. Although glucose has an aldehydic group. it does not give, 2, 4-DNP test, Schiff's test and also it de
not react with NaHSO, or NH, to form addition product.

2. The pentacetate of glucose formed upon acetylation of glucose, daoes not react with hydroxylamine, Thi
indicates the absence of aldehydic (-CHO) group.

3. The existence of glucose in a and B- anomeric forms could not be explained by the open chain structura
The a-form of glucose having m.p. 419 K is obtained by crystallising form of concentrated
solution of
glucose at 303 K while the B-form having m.p. 423 K is obtained by crystallising of hot and
saturated
aqueous solution at 371 K.

Cyclic Structure of Glucose

The limitations shown by the open chain structure of glucose can be explained by its cyclic structure, It was
proposed that glucose can form a six-membered ring in which -OH at C-5 can add to the -CHO group and
can form a cyclic hemiacetal structure. This explains the absence of -CHO group and also the existence
of
glucose in a and p-anomeric forms as

H-C-OH H HO-C-H
H OH H OH H OH

HO -H HO H HO HO
H OH H OH H4 OH
H H OH H

CHOH CH,OH CH,OH

a-D-(+)-Glucose B-D-(+)-Glucose
The two cyclic hemiacetal forms of glucose difer only in the configuration of the hydroxyl group at C-1, called
anomeric carbon (he aldehyde carbon before cyclisation) and the coresponding a and B-foms are called anomers.
It should be noted that a and B-foms of glucose are not mimor images of each other, hence are not enantiomers.
The six membered cyclic structure of glucose is called pyranose structure (a or B), in analogy with pyran.

Pyran

Pyran is a six membered ring with one oxygen and five carbon atoms in the ring. The cyclic structure of glucose
is more correcty represented by Haworth structure as given t

CHOH CHOH
H H H
5 OOH
OH OH
HO 3 OH HO H
3

H OH H OH
a-D-(+)-Glucopyranose B-D-(+)-Glucopyranose
Fructose and Its Structure
Fructose is an important ketohexose. It is obtained by the hydrolysis of sucrose. On the basis of molecula

weight determination, elemental analysis and various reaction its molecular formula is found
to be H29, and
open chain structure of it can be written as

CH,OH

HO--H
HFOH
HFOH
CH,OH
D-(--Fructose
It contains a ketonic functional group at C-2 and six-carbon atoms in straight chain. Naturally occuring fructose

is lavorotatory and belongs to D-family.

Fructose also exists in two cyclic forms like glucose i.e., a-D-()- fructose and B-D- (-)-fructose. The five
membered cyclic structure of fructose is formed by the involvement of -OH at C-5 and carbonyl group. The
frve-membered ring of fructose is named as furanose with analogy to the compound furan.

Furan

Furan is a five-membered cyclic compound with one oxygen and four carbon atoms.

HO-C-CHOH
HOH,C-C-OH
HO H HO H

H OH H OH

H H
CH,OH CH,OH
o-D-(--Fructofuranose B-D---Fructofuranose
structures as:
of fructose can be represented by Haworth
The cyclic structures of two anomers
1 6
HOH,C CHOH HOHC O OH

OH/OH H OH/CH,OH
HH 3 3
OH H OH H

a-D-(--Fructofuranose P-D-(--Fructofuranose

Disaccharides dilute acids or specific

monosaccharides On hydrolysis with
The disaccharides are composed of two units of
monomers.
enzymes they give the corresponding
nalhi 11OO5 Ph 01147623456
 H3o
CH22011 CsH20+CsH20
Sucrose Glucose Fructose

Ci2H22011
Lactose
»CsH1205+
Glucose
CsH120
Galactose

HO
C2H22011
Maltose
CgH20+CsH120s
Glucose Glucose

In disaccharides the two monosaccharides units are joined together by an oxide linkage formed by the loss
of a water molecule and the linkage is known as glycosidic linkage.
The disacharides may be reducing or non-reducing depending upon the position of linkage between the two
monosaccharide units.

() Sucrose

Ci2ha2 O,1+H2O CsH20 +

CsH20
a=66.5° D-+)-Glu cose D-+HFuctose
a=+52.55 [ab -92.4°

Sucrose is formed by the glycosidic linkage between C-1 of a-D-(+)-9lucose and C, of p-D-(-) fructose :

CH
H O H HOHC
H
**********

OH HO
HO
************ 3 4 CHOH
6
Glycosidic OH H
H OH linkage

a-D -Glucose B-D - Fructose

As the reducing parts of glucose and fructose are involved in glycosidic linkage, sucrose is a non-reducing
sugar.
Sucrose is dextrorotatory in nature but upon hydrolysis it gives the equimolar mixture of D-glucose
(l+52.5) and D-fructose (o, = -92.4) which is laevorotatory. Thus the hydrolysis of sucrose changes
the sign of rotation, from dextro (+) to laevo () and the product so formed is known as invert sugar.

(i) Maitose : Maltose is formed by the glycosidic linkage between C-1 of one glucose unit to the C-4 of
another glucose unit.

6
CHOH CH,OH
H H H H
H H
OH H OH
HO
2 -0 OH
3
H OH H OH

() (11)
a-D-Glucose a-D-Glucose
Maltose
 Maltose is a reducing sugar because the C-1 of second glucose unit is not involved in glycosidic linkage
and in solution it can show
reducing properties so it is a reducing sugar.
(ii) Lactose: Lactose is found in milk so it is also
known as milk sugar. It is formed by the glycosidic
linkage between C-1 of B-D-galactose unit and C-4 of
B-D-glucose unit.
6
CH,OH CH,OH
HO O. H
O OH
H

OH H B-linkage QH
H H

H OH H OH
B-D-Galactose B-D-Glucose
Lactose

Lactose is a reducing sugar.

Polysaccharides
Polysaccharides are long chain polymer of monosaccharides joined together by glycosidic linkages. For
example, starch, cellulose. glycogen etc. They mainly act as the food storage or structural materials.
Starch (CH,O), : Starch is the main storage polysaccharide of plants. High content of starch is found in
cereals, roots, tubers and some vegetables.

(CgH,OhasslaseC2H2,0,1 CH20g:D-glucose
Starch Maltose

Starch is polymer of a-D-(+) Glucose coming of two components namely Amylose and
a

is water soluble
Amylopectin. Amylose
component, which constitutes about 15 20% of starch. It is a straight chain polysaccharide
containing a-D-(+Hglucose units joined together by a-glycosidic linkage involving C-1 of one glucose unit and
C4 of the next. It can have 200 1000
o-D-(+-glucose units held by C1 C4 glycosidic linkage. -

CH,OH CH,OH CH,OH

O
H H
H
OH
OH H
-- -O OH O QH H -o-
2
H OH H OH H OH

a-Link o-Link
Amylose
Amylopectin isbranched chain
a
polysaccharide
insoluble in water. It constitutes about
80 85% starch. It is a branched chain
polymer of a-D-glucose units in which chain is formed by
C1-C4 glycosidic linkage whereas branching occurs by C1 C6 glycosidic linkage.
 CH,OH CH,OH

H O,

OH H -0 OH
-link

H OH H OH

Branch at C
CH,OH CH CH,OH
H H H H
H H

OH OH O OH

H OH H OH H OH

-Link 0-Link
Amylopectin
Cellulose
Cellulose is a straight chain polysaccharide composed of only B-D-glucose units. In cellulose there is B-
glycosidic linkages between C-1 of one glucose unit and C-4 of the next glucose unit. Cellulose occurs mainly
in plants and it is the most abundant organic substance in plant kingdom. It is the chief constituent of the
cell walls of plants.

HOH,C
-o O
OH
HOHC
OH

OH

OH
HOH,C
B-links
OH

OH
Cellulose
Glycogen
Its structure is similar to amylopectin with more branching than in amylopectin. It is also known as animal
starch. In body, carbohydrates are stored as glycogen and when the body needs glucose, enzymes break the
glycogen down to glucose. Glycogen is present in liver, muscle and brain. It is also found in yeast and fung.
Importance of Carbohydrates
Carbohydrates are essential for life in both plants and animals. Carbohydrates are stored in plant as starch
and in animals as glycogen. Cell wall of bacteria and plant is made up of cellulose. Furniture used in daily
life, are made in the form of wood, clothe we wear is also made from cellulose in the form of
fromcellulose
cotton fibre.
PROTEINS
The term protcin is the
derived from Greek word Proteins' which means of prime importance. Proteins are high
molecular mass complex biopolymer of oa-amino acids present in all living cells. They occur in every part of the
body and form the fundamental basis of structure and functions of life.
Proteins are the most abundant biomolecules of theliving system. Chief sources of proteins are milk. cheese
pulses, peanuts, fish etc.
Amino Acids: The compoundcontaining-NH, and-COOH functional groups are known as amino acid, depending
upon the relative position of -NH, group with respect to -coOH group, amino acids are classified into a, B. 7,8
and so on amino acid. Hydrolysis of proteins gives only a-amino acids represented as

R-CH-COOH
NH2
Proteins may contain other functional groups also.
Nomenclature of a-Amino Acids: All a-amino acids have their trival names which generally reflect the property
of the
amino acids or their sources. For example, glycine is so named since it has sweet taste (in Greek, Glycos
means cheese)
 meufa-G7lyine Aim
Classification of Amino Acids: Dependingupon the relative number of amino and carboxyl groups in the moiecuies
amino acids are classified as acidic, basic or neutral, depending upon the relative number of amino and carboxyi
groups. Equal numberof-NH, &-CoOH groups make the amino acid neutral, more -NH, group than-coo
group make the amino acid basicand more -COOH group than-NH, groupmake the amino acid acidic.> ( l u t a

Essential and non-essential amino acids:Theáminoacidswhich cannot be synthesized in the body are known
as
essential amino acids which must be taken through diet. The amino acids, which can be synthesized in the A e
body are known as non-essential amino acids. aud
Physical Properties of a-Amino Acids: Amino acids are generally colourless, crystalline, water-soluble, hign
melting solids.They behave like salts rather than simple amines or carboxylic acids due to the presence of both-
COOH&-NH, groups
n aqueous solution amino acid can exist as a dipolar ion known as zwitter ion if-COOH group loses H ion and-

NH, accepts H ion

Coon

R-CH--o-H R-CH--o N-C-

NH NH
Zwitter ion
In zwitter ionic fom, amino acids show amphoteric behaviour.
(Amino aud)
In acidic solution, the - C - O accepts a proton and gets converted to -COOH, while in basic solution the

ammonium substituent (NH) loses a proton and gets coverted to -NH,

R-CH-C-oO R-CH-ë-0 R-CH--OH

NH NH NH,
Except glycine, allother naturally occuring a-amino acids are optically active. a-amino acids exist in both Dand
L-forms. While writing the Fischer projection formula L-amino acids are represented by writing the-NH,group on
left-hand side. Most of the naturally occurring amino acids have L-configuration.
Structure of Proteins
Peptide-bond or Linkage: The reaction between two molecule of the same or different amino acids, proceeds
through the combination of amino group of one molecule with the carbonyl graoup of the other resuts in the fomaion
O H
of
of(-
(--N-) bond with the loss of a water molecule.
For example, when carboxyl group of glycine combines with amino group of alanine, we get
glycylalanine(dipepide
O
-H,O
HN-CH-OH+ H-N-ÇH-C-o-H
*****************"| H,N-CH-ë-N-ÇH-C-OH
CH CH
Glycylalanine (Gly-Ala)
Polypeptide : A dipeptide contains two amino acids linked by one peptide linkage, a tripeptide contains three
amino acids linked by two peptide linkages and so on. When number of such amino acids is
more than ten, then
the products are called polypeptides.

Protein: Apolypeptide with more than hundred of amino acids

having molecular mass higher than 10,000 u is
called protein. However, the distinction between a
polypeptide ind a protein is not very sharp. Polypeptides with
fewer amino acids are likely to be called
proteins they ordinarily have a well defined conformation of protein such
if
as insulin which contains 51
amino acids.
 Classification of Protein :On the basis of molecular shape, proteins are classifled into two types
(1) Fibrous protein
(2) Globular protein
(1) Fibrous Proteins : When the polypeptide chains run paraltel and are held together by hydrogen and disulphide
tonds, then fibre-like structure is formed, known as fibrous proteins. Such proteins are insoluble in water

r example: Keratin, Myosin etc.

Globular Proteins When the polypeptide chains coil around to give a spherical shape, the formation of
(2)
globular protein takes place. Such proteins are usully soluble in water.
For example: Insulin, Albumins etc.
Primary, Secondary, Tertiary and Quaternary Structures of Proteins
chains. Each polypeptide in a protein has
(1) Primary Structure: Proteins may have one or more polypeptide of amino acids that is said to be
amino acids linked with each in a specific sequence and it is this sequence
structure i.e., the sequence of amino acids
the pimary structure of that protein. Any change in this primary
creates a different protein.
refers to the shape in which a long polypeptide
(2) Secondary Structure: The secondary structure of protein
chain can exist.
B-pleated sheet structure. These
a-helix and
They are found to exist in two different types of structure namely
structures arise due to the
the
regular folding of the backbone of polypeptide chain due to hydrogen bonding

O
between-C- and-NH-groups ofthe peptide bond.

H9

N
N N
RCH RCH RCH
H C-O-HNC0-H-NC-0
O-CR HCR HCR
N HCR N-H--O=C
N-H-O-C
N-H
RÇH RCH RCH
~H-NHCRCO-- HCR
0-H-N R
C C C

a-Helix Structure of Proteins B-Pleated Sheet Structure of Proteins

a-Helix is one of the most common ways in which a polypeptide chain forms all possible hydrogen bondsby
twisting intoa right-handed screw (Helix)with the-NH group of each amino acid residue hydrogen bonded to

CO of an adjacent tum of the helix as shown above figure. In B-structure all peptide chains are strelcheo
out to nearly maximum extension and then laid side by side which are held together by intermolecular
H-bonds. The structure resembles the pleated folds of drapery and therefore is known as B-pleated sheet.
 (3) Tertiary Structure: The tertiary structure of proteins represents overallfolding of the polypeptide chains i.e,
further folding of secondary structure. It gives rise to two major molecular shapes namely fibrous and globular.
The main forces which stabilizesthe 2°&3° structures of proteins are hydrogen bonds, disulphide linkages,
van der Waals and electrostatic forces of attraction.

(4) Quatermary Structure: Some of the proteins are composed of two or more polypeptide chains referred to as
Sub units. Ihe spatial arrangement of these subunits with respect to each other is known as quaternary
structure.

eseeo bee

egeed

Primary Secondary Tertiary Quaternary

Structure structure structure structure

Diagrammatic representation of protein structure

(two sub-units of two types in quatemary structure

Denaturation of Proteins :
The lossinbiological activity of a protein due to unfolding of globules and uncoiling of
helix is called denaturation of protein. During denaturation secondary and tertiary structures are destroyed but
primary structure remains intact. The coagulation of egg white on boiling is a common example of denaturation.
Another example is curding of milk which is caused due to the formation of lactic acid by the bacteria present in
milk. The reverse of denaturation is called renaturation.

Example 2 : Which amino acid is optically inactive?

Solution Glycine is optically inactive due to lack of chiral C-atom.
 ENZYMES
enzyme.
biological catalyst is known
as
Colloidal solution of protein which works as

Almost all the enzymes are globular proteins.

cofactor of their activity. These
component, called the
Some enzymes are associated with some non-protein
cofactors are of two types:
Cu*, Co". Mo** etc.
) Inorganic ions such as Zn", Mg*", K", Na", Fe",
(i) Organic Molecules: They are oftwo types bond. In
molecules cofactor is held with protein by very weak
(a) Coenzymes: They are small organic riboflavine, niacin etc.
these cofactors are derived from vitamins such as, thiamine,
most of the cases

vitamins) and are bonded to protein

(b) Prosthetic Groups: These are also organicmolecules (mainly
by covalent bond.

Thus all enzymes are conjugated proteins.

Name of enzyme Reaction catalysed
Glucose and Fructose > C,H,OH
) Zymase
Sucrose Glucose + Fructose
(i) Invertase
Maltose+Glucose +Glucose
(ii) Maltase
Lactose>Glucose+Galactose
M) Lactase

) Emulsin Cellulose >Glucose

Urea CO, + NH
(vi) Urease
Proteins> amino acids
vi) Pepsin
Proteins amino acids
(vii) Trypsin
(ix) Diastase Starch Maltose

Temperature Dependence of Enzyme Activity:

with decrease
The enzymes work best at an optimum temperature range of 298Kto 313 K. Their activity decreases
or increase in temperature and stops at 273 K.

Efficiency: Even a small amount of enzymes are highly efficient. This is because their molecules are regenerated
during their catalytic activity.
Those chemical substances which tend to reduce activity of a particular enzyme are called enzyme inhibitors.
VITAMINS
Vitamins are organic compounds which are essential for normal growth of life for animals, some bacteria and
micro organism. Vitamins not synthesized
are
through food. They are essential dietary factor.
by animals (except vitamin D). Vitamins are supplied to the organiem

Classification: Vitamins are classifiedin two categories

1. Water Soluble Vitamins
2 Fat Soluble Vitamins
 (1) Water Soluble Vitamins: Vitamin-B-complex and vitamin-C are water soluble.
(a) Vitamin B, Thiamine
Its natural sources are green vegetables, soyabeans, dried pea, milk, cheese etc.
Its deficiency causes Beri-Beri.

(b) Vitamin-B,: Riboflavin

Natural Sources Grains, Cereals, Almonds, Curd, Milk etc.

Deficiency Diseases: Skin swelling around the mouth. Cracking of lips at the edges, bulging of eye
cells.
(c) Vitamin-B, : Niacin (Nicotinic Acid) and Nicotinamide
Natural Sources: Mushroom, Ground nut,
Bread etc.
Deficiency Disease: Pellagra
(d) Vitamin B,: Pantothenic
Natural Sources : Ground nut, Soyabean, Liver, Kidney
Deficiency Disease: Swelling in stomach and intestines
(e) Vitamin B: Pyridoxine
Natural Sources Yeast milk, Egg yolk, Cereals, Grams
Deficiency Disease: Convulsions
( Vitamin B12: Cyanocobalamine
Natural Sources: Meat, Fish, Egg, Curd, Milk etc.
Deficiency disease: Pernicious anemia, degradation of nervous system.
(9) Vitamin C:Ascrobic Acid
Natural source: Citrus fruits, Amla and Green leafy vegetables.
Deficiency disease: Scurvy, tooth decrease bleeding of gums.
(2) Fat Soluble Vitamins
(a) Vitamin-A: Retinol
Natural Sources Fish liver oil, Carrots, Butter and Milk

Deficiency Disease: Blindness (Hardening of cornea of eye)

(b) Vitamin-D : Calciferol
Natural Sources : Milk, Butter, Cheese, Cod liver
oil, Egg.
Deficiency Disease: Rickets in children and osteomalacia in adults, brittleness
of bones.
(c) Vitamin-E: Tocopherol
Natural Sources: Edible oils, nuts, spinach, potato, milk,
egg.
Deficiency Disease :
Degeneration of reproduction power, Anaemia.
(d) Vitamin-K: Phylloquinone

Natural Sources: Spinach and other green leafy vegetables, tomato, potato, cabbage, edible oil, liver
etc.

Deficiency Disease: Uncontrolled bleeding hamorrhage.

NUCLEIC ACIDS
chromosomes which are made up of proteins
The particles in nucleus of the cell, responsible for heredity are called
made of nucleotide units
and another type of biomolecules called nucleic acid. These are natural biopolymers
and phosphorous.
i.e., polynucleotides. Nucleic acid contain the elements carbon, oxygen, nitrogen
Their molecular weight ranges from 106 to 10.
All nucleic acids can undergo stepwise degradation to three fundamental units a heterocyclic base,
pentose sugar and phosphoric acid.
NH, or Ba(OH)2 Nucleotide

Enzyme, Nuclease
Nucleic Acid Nucleotide

NH,
MgO in H,0/A
H,PO,+ Nucleoside
Ho
Sugar+Heterocyclic bases
Sugars: Two sugars present in nucleic acid are ribose and deoxyribose.
Ribose is present in RNA and deoxyribose in DNA.
These sugars are present in furanose form.
Bases These are derivatives of purine and pyrimidine.

1
N N3

Purine Pyrimidine
Purine Bases:
NH

HC
C=N NH

NC -N CH
N CN NH
H H

Adenine (A) Guanine(G)

 Pyrimidine Bases

NH,
H H
HC NH
C N
HC N
HC
HC N
HC
N

H
O=o N

H
o
H
Uracil (U)
Thymine (T)
Cytosine (C)

base is uracil and in DNA

is replaced by thymine.
In RNA the pyrimidine
attachment of a base of 1' position of sugar is knownas
A unit formed by the
Structure of Nucleic Acid we get a nucleotide
at 5-position of sugar moiety,
nucleoside when nucleoside
is linked to phosphoric acid

5
5
Base O-P-0-H,C Base
HO- HC O-

/H H H/H
HH

OH OH
OH OH
Nucleoside Nucleotide

between 5' and 3 carbon atoms of the pantose sugar

Nucleotides are joined together by phosphodiester linkage
as shown in fig.

5' end of chain

O

Base Base
O-P-0-CH,
O-P-0-CH,
O
Sugar
Sugar
Phosphodiester 3
linkage O
OH

O-P O

Base
5'CH,
|Base
O-P-0-CH, o
0 Sugar
Sugar 3
OH
OH 3'end of chain
 chain is as shown below.
version of nucleic acid
A simplified
Base Base
Base

Sugar PhosphateSugar-Phosphate- Sugar

nfarmmation reaarding the sequence of nucleotides in the chain of a nucleic acid is called its primary structure.
Ncleic acids have a secondary structure also. Two nucleic acid chains are held together by hydrogen bonds
hehween pairs of bases. Adenine forms hydrogen bonds with thymine whereas cytosine forms hydrogen bonds
with guanine.
in secondany structure of RNA, helices are present which are only single stranded. Sometimes they fold back
on themselves to form a double helix sturcture.
5

GE
A=T-
T=A-
ET-

C=G-
G=CC
T=A-
C=G

T=

GEC
A=T-
T-A

A==T
-T=A-
-C=G
G=C

5 3'
Double strand helix structure for DNA

Example 5: The third component present alongwith deoxyribose and a base in DNA is
Solution Phosphoric acid.