Biomolecules

Biochemistry is the branch of chemistry concerned withthe chemical reactions occurringin living organism. Thes
chemical reactions in living organism involve chemical compoundscalled biomolecules. They are theibuilding blcck

Oxygen, nitrogen, sulphur and phosphorus.

of life and composed of
are mainly carbon, hydrogen,
CARBOHYDRATES
Carbohydrates are mainly produced by plants and form alarge group of naturallyoccurringorganic compounds. Theyan
and ketones or substances that hydrolyse to
yield polyhydrog
usually defined as optically active polyhydroxy aldehydes
aldehydes and ketones.
Classification of Carbohydrates
1.On the Basis of their Hydrolytic Behaviour
() Monosaccharides
The simplest carbohydrates, those cannot be hydrolysed into simpler carbohydrates are called monosaccharides. Fr
example, glucose, fructose, ribose etc.
(i) Oligosaccharides
Carbohydrates, that hydrolyse to yield 2-10 molecules of monosaccharide. They are further classified as disaccharidk
trisaccharides, tetrasacharides etc, depending upon the number of monosaccharides produced upon hydralysis ir
example, sucrose, maltose etc.
(ii) Polysaccharides
Carbohydrates, that yieldalarge number of molecules of monosaccharides (> 10) are called polysaccharides. They a
also called non-reducing sugars. For example, starch, cellulose.
2.On the Basis of Reducing Behaviour
All those carbohydrates which reduce Fehling's solution and Tollen's reagent are known as reducing sugars. Al
monosaccharides come under this category. The characteristic structural feature of reducing sugars is the presenc:
of either a-hydroxy aldehydic group-CH-CHO) as present in glucose, mannose etc., or a-hydroxy keto gru
OH

(-C0-CH,0H) as present in fructose.

Those carbohydrates which do not reduce Tollen's reagent or Fehling's solution are called non-reducing sugars
example, sucrose.
Monosaccharides
If a monosaccharide contains an aldehydic group, it is known as aldose and if it contains a keto group, itisknown2
ketose.
 Carbon Atoms
3
General Terms
Triose BIOMOLECULES 333
4
5 Tetrose Aldehyde
Aldotriose Ketone
6 Pentose Aldotetrose Ketotriose
7 Hexose Aldopentose Ketotetrose
Heptose AldohexOse Ketopentose
Ketohexose
Aldoheptose ketoheptose
Preparation GLUCOSE (CeH12O)
From Cane Sugar (Sucrose)
C12Hz2011 + H,0
CçH,206
Glucose
+ CçH1206
2, From Starch Fructose

(CçHË00s)n +nH,0 H*
Starch 393 K,
2-3 atm
nCgH1206
Glucose
Physical Properties
1. White crystalline solid
2. Its M.P. is 419 K.
soluble in water.

hemical Properties
1. Reaction with HI :0n prolonged heating with HI, glucose gives
atoms in a straight chain. n-hexane indicating the presence of six carbon
Heat
CH,OH-(CHOH),CHO+14HI. CH3(CH,)4 CH3+ 6H,0+712
n-Hexane
2. Reaction with Hydroxyl Amine (NH2OH) : This
reaction shows the presence of one carbonyl group to form
glucoxime.
CH,OH(CHOH),CHO + NH,OH ’ CH,OHCHOH)4CH = NOH + H,0
Glucoxime
3. Oxidation with Conc. HNO3 :Glucose gives sacchric acid by oxidising primary alcoholic group
(-CH,OH) and
aldehydic group (CHO) both into -COOH group.
Conc. HNO3
CH,OH- (CHOH),CHO COOH(CHOH), COOH
3[0] Sacchric acid

4. With Phenyl Hydrazine (CçHçNHNH2) :With smallamount of the reagent, glucose phenyl hydrazone is formed
CH,OH(CHOH),CHO + H,NNHçHs ’ CH=NNHCGH^ +H,0

(CHOH)4
CH,OH
formed.
With excess of reagent, glucosazone is
 Of CHEMISTRY Clas0 XII
CHO CH= NNHC,H5
3cEH_NHNH,
CHOH = NNHC,H5 + 2H,0 + NH + CoH5NH
(CHOH), (CHOH)3
CH,0H CH,OH
Glucosazone
5. With Br, Water : Glucose gets oxidised to form gluconic acld on
the red colour of bromine water. It indicates the presence of an reaction with Br2 water. lt readily decolourises
bromine water. aldehydic group. Pructose does not react with
CHO COOH
Br, Water
(HOH)4 (CHOH)4
CH,OH CH,OH
Gluconic acld
6. Acetylation :Glucose on acetylation with acetic anhydride gives
glucose pentaacetate confirming the presence of
five-0H groups.
CHO CHO

(HOH), + 5(CH,CO)20 (CHOCOCH3)4 + 5CHgCOOH

CH,OH
CH,0COCH3
Glucose pentaacetate
On the basis of above reactions, its configuration was given as:
CHO
H OH

HO

H OH

-OH
CH,OH
D+}-Glucose
Dand L Designations of Monosaccharides
The letters 'D' and '= before the name of any compound indicates the relative configuration of a particular stereoisomer.
This refers to their relation with a particular isomer of gtyceraldehyde.
CHO CHO
H4 OH HO-H
CH,OH CH,OH
(+}-Glyceraldehyde (--Glyceraldehyde
All those compounds which can be chemkcally correlated to (+) isomer of glyceraldehyde are said to have D-configuration
whereas those which can be correlated to (-) isomer of glyceraldehyde are said to have L-configuration.
CHO
H -OH
HO -H
CHO
H-oH

CH,OH CH,OH
D-{"}-Glyceraldehyde
D-(+}-Glucose
It maybe remembered that 'D' and 'L have no relation with the optical activity of the compound.
 BIOMOLECULES 335
bjectionsAgainst Open Chain Structure of Glucose
1. Glucoseeven though contains -CHO group but does not react with NaHSO3, ammonia and Schiff's reagent.

The pentaacetate of glucose does not react with hydroxyl amine indicating the absence of
3. Glucose exists in two stereoisomeric forms, a-D-glucose and p-D- glucose with different free-CHO
melting pointsgroup.
and their
methods of preparation.
It does not give 2, 4-DNP dertvative.
Glucose
clic Structure of
Theabove obbjections have been explained by the ring (cyclic) structure öf glucose. In the cyclic structure of glucose,
-OHgroup at Cg and -CHO group at C combine to give a 6-membered ring (pyranose structure). These are called
scher Projection Formulae.

Hç-OH HC
HC-OH H2-OH H -0H

HO Ç-H HO ç-H HO ç-H

HC-OH HC-OH HÇ-OH
H-S.
CH,OH CH,OH
B-D(+)-Glucose or
a-D(++Glucose or D+}-Glucose B-D(+}-Glucopyranose
a-D(+}-Glucopyranose (Open chain form )

represented by hexagonal structure (Haworth Projection formulae).

The above cyclic structures can also be
CH,0H cH,OH
H H OH
H
1
OH
OH H OH HO H
HO 2 3
3
OH
OH B-D(*}-Glucopyranose
forms are intramolecular
a-D(+}-Glucopyranose
straight and cyclic forms. The cyclic
aqueous solution, glucose rapidly interconverts between
i solution. For most of five and six carbon sugars,
the cyclic forms
In spontaneously and reversibly in
hemiacetals. They occur
Bglucose(64%)
predominate in solution.
a-glucose(36%) Open chain form (0.02%) are
isomers and differ in the configuration only around C atom. They
and
B-D-()-glucose are optical carbon orglycosidic carbon.
a-D-(+)J-glucose Ccarbon is known as anomeric called
anomers and offan optically active compound with time to an equilibrium value is
called rotation
change in specific
The spontaneous BD-Glucose
mutarotation. a-D-Glucose Open chain form
[ao=+111°C [ap=+ 52.5° laß=+192
 Fischer projection formulae can also be BIOMOLECULES 337
represented by Haworth Projection formulae as follows:
CHOHO cHOH tHOHO OH

H HO
OH HO
H

ÖH H
OH
a-D-{-)-Fructofuranose B-D---Fructofuranose
sacharides
C1zHz20,,)
Lose (Cane Sugar,
obtainedI commercially from cane sugar or sugar beets.
ts
gives equimolar mixture of D-(+)-glucose and D-(-)-fructose.
C2H2011 +H,0 ’ CçHi20% + CçHy206
Sucrose D{+)-Glucose D-{-}Fructose
Thesetwo monosaccharides are held together by gycosidic linkage.
°CH,OH
15
H
H
H HOH,Ç
2
OH H OH,
OH
3 4
cH,OH
Glycosidic
H OH linkage OH

a-D-(+)-Glucose B-D{--Fructose
Haworth projection formula of sucrose

nvert Sugar of
sucrose upon hydrolysis yields dextrorotatory glucose and laevorotatory fructose. The dextrorotation
Dextrorotatory hydrolysis, the
52.59) is less than the laevorotation of fructose (-92.4°) so the mixture is laevorotatory. Upon
glucose (+
(-). Hence, the product is known as invert sugar.
sign of rotation changes from dextro (+) to laevo
Maltose (Malt Sugar, C12Hz2011) unit (1) is linked to C, of another glucose unit
(II). It is
a-D-glucose units in which C of one glucose
Itis composed oftwo produced at C of the second glucose unit in
solution.
free aldehydic group can be
areducing sugar as the
SCH,OH SCH,OH
H H
H H
OH
OH OH
N3
OH
H OH
H OH
(1)
(0 a-D-Glucose (Reducing glucose unit)
glucose unit)
a-D-Glucose (Non-reducing
Haworth projection formula

lactose (Milk Sugar, C12Hz2011)B-D-glucose. It is a reducing sugar.

Is composed of B-D-galactoseand
 °CH,OH
°CH,OH OH
|5
HO H 1
H
OH H
OH H
H
3
OH
H OH B-D-Glucose
B-D-Galactose

Polysaccharides
Polysaccharides are composed of large number of monosaccharide units joined together by glycosidic linkages.
Starch [Amylum, (CçHo0s)n
It occurs as microscopic granules in the roots, tubers and seeds of plants.
ltis dietary source for human beings. It is a polymer of a-glucose and consists of amylose and amylopectin.
CH,OH cH,OH
H H
H
OH OH

3 2 3 2
H OH
Bycosidiclinkage
OH
Amylose
Amylose is water soluble component and makes 15-20% of starch. It consists of 200-1000 a-D-(+)glucose units held by
C-C4 glycosidic linkage. It is a long unbranched chain.
CH,OH CH,OH
H H
H
OH OH
-a-link

H OH H OH
-C-çlink
CH,OH CH CH,OH
H
H
OH H
H OH 1
OH H

H OH H OH
a-link H OH
a-link
Water insoluble amylopectin has a Amylopectin
structure similar to that of amylose with the
are branched. It constitutes about 80-85% of starch. eexception that in amylopectin thechains
Cellulose
It is astraight chain polysaccharidee
by glycosidic linkage between C of exclusively occursin
one glucose unit and plants. It is composed only of whicharejoined
C, of the next
glucose unit. B-D-glucose units
 HOH,
H

OH H
HOH,C
H
H OH

OH H

HOH,C
H OH
B-linkage

OH H

OH
Cellulose

Giycogen
starch. It occurs in liver. muscles and brain and is broken down
tis an energy storage molecule and is also called animal
into glucose. It is also found in yeast and fungi.
Inportance of Carbohydrates
the functioning of living organisms.
1. They act as store house of chemical energy for
acids.
2. They are essential components of nucleic
cells and are essential component of ATP.
3. They form structural materials for
PROTEINS
15% of
acids with molar mass ranging up to more than 50 million. About
Chemically proteins are the polymers of amino
on
the human body weight is protein. (-CO0H) function groups. Only a-amino acids are obtained
and carboxyl
Amino acids contain amino (-NH,)
hydrolysis of proteins. R-CH-C0OH

NH2
a-amino acid (R=side chain)

Classification of Amino Acids of amino or carboxyl groups in their molecule, the

amino acids are acidic(more
the relative
number
amino groups than carboxyl groups) or neutral (equal number of
Depending upon amino groups), basic
(more
carboxyl groups than
groups). non-essential amino acids. They are 10in number.
amino and carboxyl can be synthesised|in the body are known as
in our diets. They are known as
The amino acids which are not synthesised in our body and they must be supplied
acids
10 out of 20amino
essential amino acids.
Acids
Structure of a-Aminoexist as dipolar ion or Zwitter ion.
can also
The amino acid
R
R-Ç-coo

pENH ONH
Zwitter ion
 This structure is also known as internal salt. In this form, amino acids show amphoteric behaviour. At a
dipolar ion does not migrate to any electrodes passing electric current through their solution. This is called certain pH
point ofthat amino acid. Each amino acid has acharacteristicisoelectric point. For neutralamino
acids.isoeleIcsotreileandcptrpioeint
is slightly lessthan pH7(Glycine =6.1). For acidic amino acids, it lies between pH 3.0-5.4 (aspartic acid =3.0)
basic amino acid, it lies between pH 7.6-10.8 (lysine =9.7). At isoelectric point, an amino acid has the least
water and this property is used in the separation of different amino acids obtained from the hydrolysis of protein. in solublity
Peptides and Proteins
a-amino acids are connected to each other by peptide bond or peptide linkage ( CONHH. TheNH, groun af.
amino acid molecule combines with the-cóoH group of another amino acid molecule to form a peptide bondne
water molecule is given out.
H,NCH, -C0OH + H,N-CH-C0OH
Glycine -H,0
H,N -CH, co-NH CH-coOH
Alanine Peptide linkage
(Glycylalanine)
The above peptide linkage is dipeptide.
When a large number of amino acids (more than ten) are combined, the products are called polypeptides. Apolypeptide
with more than hundred amino acid residues having molecular mass higher than 10000 u is called a protein.
Classification of Proteins
On the Basis of Molecular Structure
It is of two types:
1. Fibrous Proteins
These types of proteins consist of linear thread like molecules which
tend to li side by side to form fibres. The molecules are held together
at many points by hydrogen bonds or disulphide bonds. They are
usually insoluble in water. For example, keratin in skin, hair, nails and
wool; collagen in tendons; fibroin in silk; myosin in muscles etc.
2. Globular Proteins
In thistype of proteins, the molecules are folded together into compact H

units forming spheroidal shapes. They are held together by hydrogen

bonds and are soluble in water or aqueous solutions of acids, bases or
salts. For example, albumin, insulin. As compared to fibrous proteins, H N
they are very sensitive to small changes in temperature and pH.

(a)
(b)
Structure of Proteins Fig. 10.1. a-helix
structure of proteins
The protein's structure and shape can be usually studied at four different levels:
1. Primary Structure
The sequence of amino acid residues in polypeptide or protein, is called primary structure. Any change in the primary
structure creates a different protein.
R R"

U=0
H R
 secondary Structure
the BIOMOLECULES 341
trefersto shape in which along
structure. a-helix polypeptide chain can
structure is a right handed helix, with 3.6 exist. They are found to exist in a-helix and B-pleated sheet
byhydrogen bonding. amino acid residues per turn and a
inß-structure all peptide 13 member ring is formed
chains are stretched out to
nearly maximum extension and Ithen laid side by side
together by intermolecular
hydrogen bonds. which are held

RH RCH RCH

HCR
HCR HCR

RCH RCH RCH

C=0-4 =0.4A
HCR HCR HCR

Fig. 10.2. B-pleated sheet structure of proteins

3. Tertiary Structure
This structure represents overall folding of the polypeptide chains ie, further folding of the secondary structure. Fibrous
and globular structures arise due to tertiary structure.
Secondary and tertiary structures of proteins are stabilised by hydrogen bonds, disulphide linkages, van der Waals' and
electrostatic forces ofattraction. This structure also refers to overall three dimensional shape of a protein.

Tertiary
Quaternary
Secondary structure
Primary structure
structure structure
(two sub-units of two types in quaternary structure)
Diagrammatic representation of protein structure
Fig. 10.3.
 1. Primary 2. Secondary
structure 3. Tertiary 4. Quatermary
structure structure structure
N R groups
Haeme group
Fig. 10.4. Primary, secondary, tertiary and quaternary
structures of haemoglobin
4. Quaternary Structure
Many proteins exist as stable and
The overall structure of a proteinordered, non-covalent aggregates of more than one polypeptide chain (called subunits).
arising from the spatial arrangement of these subunits
called its quaternary structure. with respect to each other is
Denaturation of Proteins
The protein with a unique three
dimensional structure found in living system showing biological activity is a
native protein. When this native protein is called
are disturbed. So that globules unfold and subjected to physical change like temperature, pH etc., the hydrogen bonds
helix gets uncoiled. Thus, protein loses its
denaturation of protein. During this, 2° and 3° structures biological activity, This is called
are destroyed but 1° structure remains
coagulation of egg while on boiling, curdling of milk. intact. For example,

ENZYMES
Enzymes are biological catalysts and catalyse the
biochemical reactions. Almost all enzymes are globular proteins
Enzymes show specificity for both, the reaction and the substrate.
For example: Ci2tlg2011
Maltose
2C,H,206
Maltose Glucose

Mechanism
They act as catalysts by lowering the activation energy. They are needed
enzyme, the degree of specificity shown for the substrates can vary widely. only in small quantity. Depending unon the

HORMONES
Hormones function as chemical messengers in the body. They are produced in the endocrine glands and
tralt the
organs and tissues inthe bloodstream. Chemicallythey may be steroids,(eg, estrogenand androgen),
.polypeptides
insulin and endorphins) or amino acid derivatives (eg. epinephrine and norepinephrine). Hormones affect growth (eg
and
 welopment, metabolism, sexual functions and BIOMOLECULES 343
glucosein the
yelof blood. Steroid hormones reproduction. They also affect
regulate tissue growth and moods. Insulin and glucagon regulate the
andadrenal cortex.
enads reproductive processes
and are secreted by

VITAMINS
compounds are required in small amounts in the diets of
onganic
hese
reproduction. Most of them cannot be animals in order to ensure healthy growth and
synthesized in our body but plants can synthesize almost all of them.
assfication of Vitamins
1.fatsoluble vitamins : Vitamins A, D, Eand Kare fat soluble and water
Jiver.
insoluble. They are stored in adipose tissue and
2. Water soluble vitamins : Vitamins of Bgroup and vitamin Care water soluble. They cannot be stored in the body
(exceptvitaminB2) anddhence, their in take be should regular.
Table 10.1 Some important vitamins, their sources and their
deficiency diseases.
S. No. Vitamins
Sources Deficiency Diseases
1 Vitamin-A Fish liver oil,carrots, butter and milk Xerophthalmia (hardening of cornea of eyes).
night blindness
2 Vitamin-B1 Yeast, milk, green vegetables, cereals Beri-beri (loss of appetite, retarded growth)
(Thiamine)
3 Vitamin-B2 Milk, egg white, liver, kidney Cheilosis (fissuring at corners of mouth
(Riboflavin) and lips), digestive disorders and burning
sensation of the skin

4. Vitamin-B6 Yeast, milk, egg yolk, cereals and grams Convulsions

(Pyridoxine)
5. Vitamin-B12 Meat, fish, egg and curd Pernicious anaemia (RBC deficient in
(Cyanocobalamine) haemoglobin)
6 Vitamin-C (Ascorbic Citrous fruits, amla and green leafy vegetables Scurvy (bleeding gums)
acid)
7. Vitamin-D Exposure to sunlight, fish and egg yolk Rickets (bone deformities in children) and
osteomalacia (soft bones and joint pain in
(Ergocalciferol) adults)

8. Vitamin-E Vegetable oils like wheat germ oil, sunflower Sterility, increased fergility of RBCS and
oil, etc. muscular weakness
(Tocopherol)
9. Vitamin-K
Green leafy vegetables, cereals Increased blood clotting time haemmorhage
(Phylloquinone)
10. Vitamin-H (Biotin) Yeast, liver, kidney and milk Dermatitis, loss of hair, paralysis

Avitamingses : Multiple deficiencies caused by lack of more than one vitamin are very common in human beings. This
Condition of vitamins deficiency is called avitaminoses.
Hypervitaminoses : The condition of excess intake of vitamins is known as hypervitaminoses
NUCLEIC ACIDS
The nuclee of the cell transmits the inherent characters of an individual from one generation to the next. This transmis
consists of chromosomes which are made up of
called heredity. The nucleus proteins and nucleic
sion of characters is
and Ribonucleic Acid(BNA)
acids. Nucleic acids are oftwo types: Deoxyribonucielc Acid (DNA)
 The repeating unit they are regarded
tides. A nucleotide (monomeric
unit) of nucleic acids are called nucleotides. Therefore, as
is consisted of :
1. Anitrogenous base (nitrogen containing
heterocyclic
NH2 NH2
polynuces.
base).
2. Apentose sugar.
3. Aphosphate group.
1.A Ntrogenous Base: There are two types of
base known as purines and pyrimidines. nitrogenous ADENINE (A)

H
()) Purines : Two purines found in nucleic acids are
HN HN
adenine (A) and guanine (G).
(0) Pyrimidines : Three pyrimidines in nucleic acids are HzN
uracil (U). thymine (T) and cytosine (C). HZN GUANINE (G)
H
DNAcontains A, G, T and Cbut RNA contains A, G, Uand C. Fig.10.5. Structure of purines : adenine and guanine

NH2

CH3
HN HN

H H
URACIL (U) THYMINE (T) CrTOSINE (C)
(occurs in onty RNA) (occurs in only DNA) (ocCurs in both DNA and RNA)

Fig. 10.6. Structures of pyrimidines : uracil, thymine and cytosine

"çH,OHO OH CH,OMO OH

H
H

2 2

OH OH OH
B-2-deoxyD-ibose
B{DH-ibose

2. A
pentose Sugar :There are two types of sugarspresent in the nucleic acids RNA contains B-D-ribose but in DNA, there
is B-D-2-deoxyribose.
3. A
phosphate Group : They are responsible for the linkage in nucleic acid polymers.

0- P 0

The phosphate group is bonded to a hydroxyl group of sugars.

Nucleosides and Nucleotides
Anucleoside consists of only two basic components ie, a pentose sugar and a
nitrogenous base. Depending upon the type of the sugar present, nucleosides
are of two types: (1) Ribonucleosides and (i) Deoxyribonucleosides.
HOCH,
Base -Nglycosidicbond
Anucleotide contains all the basic components ofnucleicacid ie, aphosphoric
acid group, a pentose sugar and a nitrogenous base. Sugar
When a large number of nucleotides are connected, we get polynucleotide.
nucleoside
Fig. 10.7. General structure offa
 BIOMOLECULES 345
Base
Base Base

-Sugar0-P0 -Sugar-0P-0 Sugar

OH OH Jp
Nucleic acid or polynucleotide
structureofDNA
2.0 nm
The three dimensional double helical structure of DNA 3
5
was given by Watson and Crick in 1953.They
DNA polymers form a duplex
proposed
that
of two strands of
structure which are
polynucleotide chains consisting
-A=T
coiled around each other in the form of double helix.
The nucleotides of each strand of DNA are A=T
connected
hy nhosphate-ester bonds. The base pairs of the two
trands are linked together through hydrogen bonds. -C=G
Apurine base of one strand is always paired with a -G=c-\.10.34nm
Dvrimidine base of the other strand. The only possible -T=A
C=G
pairing in DNA are between Gand C through three
hydrogen bonds (.e., C=G) and between A and T
through two hydrogen bonds (A =T), The two of the 3.4
-T=A

helix are complementary and not identical. The diameter nm

-G=C
A=T
of double helix is 2 nm and the double helical structure
repeats at interval of 3.4 nm when it completes one turn.
This one turn corresponds to ten base pairs.
When the DNA strands separate on heating it is called
-A=T
-T=A
-C=G
melting but on cooling, they again hybridize and it is -G=C
known as annealing. The temperature at which both the
5
strands are completely separated from one another is 3

called melting temperature (Tm). Fig. 10.8. The double a-helix structure of DNA. The two nucleotide
strands are held together by specific hydrogen bonding between
DNA acts as acarrier of genetic information from parents bases. The numerals 5', 3' indicate that the free hydroxyl groups of the
to offsprings and is involved in synthesis of RNA. terminal deoxyribose units are present at 5', 3' positions respectively

RIBONUCLEIC ACID (RNA)

in other living organism, it occurs with DNA. Each
It is found as the genetic material in some plant and animal viruses while
group. RNA is single stranded
ribonucleotide consists of a pentose sugar, nitrogenous bases (A, G, G, U) and phosphate
pairing can OCcur between A andUand Gand C.
except for certain viruses. However, complimentary base

Biological Functions of Nucleic Acids heredity. It helps in transmitting characteristic features

DNA is geneticmaterial of the cell and torms the chemical basis of duplicates and similar copies are transferred to the
division, it
and maintain the identity of a species. During mitosis cell in turn are coded by DNA. The process
dauchtar calls Proteins are synthesized in the cell through RNA molecules which
from DNA is calledtranscription and that of protein form RNA is called translation. This depicts the
ofsynthesis of RNAin protein synthesis.
role of nucleic acids