~tG- JEE Main Ch .

ernist~

~CH=CH2 14. (b): Chain growth polymerisation is an

. . additi
n'--8) +nCH2 =yH polymerisation which involves homopolymerisation °11
Peroxide , arid
Styrene CN copolymerisation both.
Acrylonitrile 0
ll ,
15. (b): -f.NH-(CH2) sCONH-CH2-Cf;r
t\
Nylon-2-nylon-6

It is a polymer of glycine and aminocaproic acid . .

and is
biodegradable polymer. a

000

,,
,1~ '

..,
l t I I
~

·. ,,,

..,j ;

' I

I : ._,
I

I•

-- • '- • ,. I '

• •• 1 I

I • i; . l 1 • } - •• ' '

.. 4 , •
 Biomolecules

carbohydrates : Monosaccharides, Cyclic Structures of Glucose and Fructose, Chemical

OReactions of Glucose, Disaccharides, Polysaccharides O Proteins and a-Amino Acids :
Classification of Alpha Amino Acids, Peptides, Proteins and their Classificat.ion, Enzymes
·l
r,
0 Other Biomolecules : Vitamins, Nucleic Acids

0 . carbohydrates , ·, J • .i

'Jhe essential organic compounds present in living Monosaccharides containing an aldehyde (-CHO)
. ms are called biomolecules. Biomolecules are
group are called aldoses.
organis,vdrates amino
. aci'ds, proteins,
. enzymes, 1·ipi'ds,
b h
caro:., ' .. Monosaccharides containing a keto (> C = O) group
1 ·c acids hormones, vitamins, etc.
,rue ei ' are called ketoses.
► carbohydrates · Depending upon number ofcarbon atoms, monosaccharides
1hey are polyhydroxy aldehydes or ~etones or substances are known as trioses, pentoses., hexoses and so on.
that generally give these on hydrolysis and contain at least Configuration of Monosaccharides
one chiral carbon, hence optically active.
The letter 'D' before the name of the monosaccharides
1heir general formula is CxCH2O)1 where x and y can be 3,
indicat~s that the -OH group at the carbon atom next to
4, s, ...', etc.
the terminal (or penultimate) carbon atom is towards right.
'cias~ification of Carbohydrates ' Whereas, letter 'L' refers to left position of penultimate
,, I I • •

.1·. . Based on molecul_ar size . - OH group. Toe signs (+) and (-) just before the name
(i) Monosaccharides, (ii) Oligosaccharides and of the carbohydrate indicate their dextro and laevorotatory
. (iii) Polysaccharides. · nature respectively.
2. Based on taste The D and L system is based upon the configuration ~f
Carbohydrates with ·sweet taste ar~ called while suga~s glyceraldehyde.
those witho~t a sweet taste ar~ called non-sugars. It may be e.g., CHO CHO
noted that all mo~o- and oligosaccharid~s are sugars while I* 1.
polysaccharides are non-sugars.' · , H-C-OH HO-C-H
• • -, # • f• I I
3. .. Reducing and non-reducing sugars · - . CH2 0H CH20H
Carbohydrates which ~ed~ce Tollen's ~eagent (ammoni~c·a l D(+)•Glyceraldehyde L(-)-Glyceraldehyde
silver nit~ate) ~d. Fehling's solution -are called r~ducing
H-C=O H-C=O
sugars while those which do not reduce these are called non- I. I '
red_u~ing s~gars. For example, both glucose and fructose H-C-H H-C-OH
I I
are reducing sugars while' sucrose is a non-reducing sugar. H-C-OH
H-C-OH
I. · Monosaccharides , I I
H-C-OH H-y-OH
Monosaccharides are the simplest carbohydrates which I
cannot be ! hydrolysed into simpler compounds. Their CH;PH CHi()H
general formula is (CH2O)" where n =3 to 7. D(-)-2-Deoxyribose D(+)-Rlbose
 ~-te- JEE Main Chemistry

0
H-c=o CH2-OH Oc',. ,......H ~ ......-H
I I -.....;:c
H-C-OH c=o r·------r. _____ _
I I r------l--------: :HO-C- H:
HO-C-H HO-C-H :H-C-OH :
I I ~------t--·-----· ~------··t------!
H-<r-OH H-C-OH HO-C-H HO-C-H
H-C-OH
I I I .
H-C-OH
I I H-C-OH H-r-OH
CHzOH CH.PH I
D(+)-Glucose D(-)-Fructose H-C-OH H-y-OH
I
Cyclic structures of Monosaccharides CH2OH CH2OH
All the pentoses and hexoses undergo !ntramolecular D(+)-Glucose D(+)-Mannose
hemiacetal or hemiketal formation and exist in cyclic Epimers
hemiacetal or hemiketal structures. Generally, in the Glucose or Dextrose or Grape Sugar (C6 H Q )
12 6
free state, they occur as six-membered cyclic structures
D-(+)-Glucose exists in two stereoisomeric forms ,·
containing one O-atom called pyranose form. However, - , .e.,
a-glucose and j3-glucose. a-D-(+ )-Glucose has a meltin
in the combined state, some of these such as ribose,
point of 419 K and has a specific rotation of +11}
2-deoxyribose, fructose, etc. have five-membered cyclic
j3-D-(+)-Glucose has a melting point of 423 Kand has a
structures containing one oxygen-atom called the furanose
specific rotation of+ 19.0°.
form. In contrast, trioses and tetroses have open chain
Glucose can be prepared from sucrose by boiling with
structures.
dil. HCl or H 2SO4 in alcoholic solution.
Cyclic structures of Glucose and Fructose (Anomers)
w
Due to ring formation, hemiacetal or hemiketal carbon C12H22On + H2O~ C6H12O6 + C6H12O6
Sucrose Glucose Fructose :
C 1 becomes chiral and hence, the monosaccharide exists
in two stereoisomeric forms, the a and the 13-forms. If the Commercially it is obtained by hydrolysis of starch by
-OH group attached to hemiacetal or hemiketal carbon is boiling it with dil. H 2SO4 at 120°C under pressure.
towards right it is called an a -form and if the -OH group is
towards left it is called 13-form. Such a pair of stereoisomers
which differ in configuration only around hemiacetal or
hemiketal carbon (C1) are called anomers and the carbon is ► Chemical Reactions of Glucose ·
called anomeric carbon or glycosidic carbon. Open chain structure of glucose contains one aldehyde
6CH OH group (-CHO), on~ primary alcoholic group (- CH2OH)

.~:~~-
2
and four secondary alcoholic groups (-CHOH). Thus,
OOH .
glucose shows the reaction of both alcoholic group and
4 gH H 1~ aldehyde group. · · '
H~H HO 3 2 H
~ Mutarotation
H OH H OH
a-D-(+)-Glucopyranose ~-D-(+)-Glucopyranose
When aqueous solution of either of two isomeric forms,
(Haworth structure) (Haworth structure) of glucose is allowed to stand, it gets converted into the
6 I equilibrium mixture of both the a-and the ~-forms with a
HOH2C ~ OCH20H small amount of the open chain form.
s 2 a As a result of this equilibrium, the specific rotation of a
H H freshly prepared solution of ex-glucose decreases from
H 4 3 OH
+ 112° to 52.7° while that of ~-glucose increases from + 19°
~~~ .
OH H
a-D-(-)-Fructofuranose fj-D-(- )-Fructofuranose ex-Glucose ~ Equilibrium mixture ~ ~-Glucose
Monosaccha rides which differ in con.figuration at a carbon
Ialv = + ll2° [alv= + 52.7° [ a)D = + I?
0

atom other than the anomeric carbon are called epimers. This change in specific rotation of an optically active
Thus, glucose and mannose which differ in configuratio n at compound with time to an equilibrium value is called
Ci are called Ci-epimers while glucose and galactose which mutarotation. All monosaccharides and reducing
differ in con.figuration at C,c are called C4 -epimers. disaccharides undergo mutarotation .
Biomolecules

S(CH CO 0
1, Acetylation -----,-A..:.. . ➔ CHO ,
cct_icJ..an:..:hy.:. .dri:..:d-c
I
(1HOCOCH3)4 + 5CH3COOH
CH2OCOCH3
.r. I • Glucose pentaacetate

+(O), Bf / 0
'd ti' r-t---M'-il.:.;..do-xi"-da-4tio...:.n~CH2OH(CHOH)4COOH
Z, Oxi a o,,..__ ___, Gluconic acid
HN
'--t---Str-o-ng_o... lo-n➔ HOOC(CHOH)4COOH
xida1-t_
Saccharic acid

+2(H], (Na+Hg)/ 0
~i---,.;........;.;..;.-~.11..4cH2OH(CHOH)4CH2OH
3, Reductio•n ---~ Sorbitol
HUP
CH3CHI(CH2hCH3 + CH3(CH2)4CH3
2-lodohexanc n-Hcunc

+2Cu2++50W
.o-n4, COOH
r-+-F-e~-nt-s-sol-uti-
I
4. Reducing Nature (CHOH)4 + Cu2O + 3H2O
I Redppt.
CH2OH
Gluconic acid
2(Ag(NHJz)0H
'--+---'--"c:....-..:;.:.:.._➔ Gluconic acid + 2Ag + 4NH + H O
Tollcns' reagent 3 2
(Mirror)
GLUCOSE 1-------
5. Reaction with ---+------=-H: ..:::CN~-~ CH2OH(CHOH)4CH(OH
hydrogen cyanide Glucose cyanohydrin CN

6. Reaction with phenyl <;HsNHNHi CH= NNHC H ¼HsNHNHi >CH= NNH~Hs -HiO >CH= NNHC6Hs
·I 6 5 -¼ HsNH2, -NH3
hydrazine(osazone
-H20 I <;HsNHNH2 \
CHOH C=0 C = NNHC6Hs
formation) (D-(+)
I I I
-glu,cose con!aining _! ' (CHOH~ (CHOHh (CHOHh
aldehyde group gives I I I
osazone formation CH2OH CH2OH CH2OH
Glucose phenyl hydrazonc Glucosaz.one
reaction)

CHOH CttiOH
. I
• :, I •
II ' c-o
C-OH
I
1,2-Enolization, (I ) - - - l : (CHOH>J
7:Action of alkalies CHOH 3 ~ I
; I
,, . I CttiOH
CHpH
Enediol D-(-)-Fructose
(Fructose reduces Tollcns' reagent and Fchling's
.1l solution because of above isomcrization reaction.)
CHO
I
HO-C-H
·I ,
J •
(CHOHh
I
iiJj .~ i< . CH;PH
· D-(+)-Mannose
•

t\t-tG- JEE Main Che

lllistr~

II. Disaccharides (B) Maltose or Malt Sugar

Disaccharides are the carbohydrates which on hydrolysis Maltose, commonly kno~ as malt sugar, , is
give two molecules ofthe same or differentmonosaccharides. homodis. accharide. It is obtamed by the partial hydrolys·a
Their general formula is C12H Q •
22 11 of st arch WI.th the enzyme diastas
.
e or P-amylase pr IS
esent in
In disaccharides, the two monosaccharides are joined malt (sprouted barley salt). It 1s,dextrorotatory in nature.
together by glyco~idic linkage. A glycosidic bond is formed
Hydrolysis
when hydroxy group of the hemiacetal carbon of one · .2(C6H 100s)n + nH20 Diastase > nC12H 220
monosaccharide condenses with a -OH group of another Starch 11
Maltose ,
monosaccharide to give -O-bond. Upon hydrolysis with dilute acids or with enzyme m
A few important disaccharides are: (+)-sucrose, (+)-lactose, a1tase
(present in yeast), it forms two molecules of D-(+)-glucose
(+)-maltose and (-)-cellobiose. The disaccharides may
be either reducing (lactose, maltose) or non-reducing only.
Hydrolysis
(sucrose) in nature. c12H 220 11 + H20 > 2C6H 12o6
(A) Sucrose or Cane sugar orTable sugar (C H 0 ) (+)-Maltose D-(+)-Glucose·
12 22 11
Sucrose is most common heterodisaccharide. It is Maltose is a reducing sugar, undergoes osazone format·
dextrorotatory in nature. Upon hydrolysis with dilute , ion,
mutarotation and reduces Tollens r~agent and Fehling's
mineral acid (HCI) or by enzyme, invertase it forms solution. In maltose, two glucose uruts are joined by an .
equimolar mixture of D-(+)-glucose and D-(-)-fructose.
a:-glycosidic linkage between C-1 of non-reducing glucose
Hydrolysis unit and C-4 of other reducing glucose _unit.
C 12 H22011( s) + H20 >
(+)-Sucrose C6H12 06(aq) + C6Hl2 06(aq) H\./,O H
[a]0 = + 66.5°
H
(+)-Glucose[a)0 =+52. r and 2
H OH
(-)-Fructose [a)0 = + 92.4° or invert sugar 3
HO HO H
The mixture is overall laevorotatory. Thus, the H
H
H O
~ H
4
5
OH 0 =··1
hydrolysis of sucrose brings about a change in the sign H s H
6 .. 6
of optical rotation, from dextro (+) to laevo (- ) and CH20H
CH2 0H
such a change is known as inversion and the eq~o lar · Reducing unit Non-reducing unit 1, 1/
mixture of D-(+)-glucose and D-(-)-fructose which
Fischer structure for maltose
sucrose gives on hydrolysis is called invert sugar. . ll .
Both glucose and fructose are reducing in nature, ·'
sucrose is non-reducing, because the hemiacetal
and hemiketal groups of glucose and fructose are
also linked with each other through oxygen atom 0
(glycosidic linkage) and are not free to show their H, OH
reducing characters. (Non-reducing unit) \ :,d,dng wtit)
l, 4-a-Glycosidic linkage
H
CH20H
H OH 0 Haworth structure for Maltose
HO H
HO H (C) Lactose or Milk Sugar
H OHO
H H OHO Lactose is a heterodisaccharide found in the milk of
H mammals. Upon hydrolysis with dilute mineral acid (e.g.,
CH2 0H
CH20 H HCI) or with eneyme Iactase, it gives equivalent·am~unts
Glucose unit Fructose unit ,. of D-(+)-glucose and D-(+)-galactose which are epimeric
Fischer structure for sucrose in nature.
CH20H Hydrolysis
C12H2 2011 + H20 >C6H12 06 + C6H12O 6
(+)-Lactose D-(+)-Glucose D-(+)-Galactose

H
--~: :PsHe
rH,OH
. oH
Lactose is a reducing sugar which undergoes· osazone
formation, mutarotation and reduces Tollens' reagent
and Fehling's solution. In lactose, C-1 of galactose unit
OH H (non-reducing unit) is attached to C-4 of glucose unit
Glucose unit Fructose unit
Haworth structure for sucrose (reducing unjt).
 ieeufes ,
g;of110
1
HO H
OH H 2 6
H 0 HO 3
OH o Cf120H
H
4 H H4 H. ~H Ott
H. H s 1 O 4
OH 'dic
I a-l , 6-Glycos1
6 ....._____,_v linkage
6 •
CH20H H 0
CH20H 1 OH H ott 1

~HH ~OQo-
Galactose Glucose 6 6
(Non-reducing) (Reducing) I •
•:: '· Fischer structure for lactose
6
., CH20H H3
H H H OH H OH
l a- 1, 4-Glycosidic
3H linkage
· 0
o---- H
Structure of Amylopectin
H H20H
(Galactose) · (Glucose) (B) Cellulose
Non-reducing unit Reducing unit
''..
Cellulose is widely distributed in plants and forms more
Haworth structure fo,r Lactose
than 50% of living matter. Cellulose is a linear condensation
Ill, , polysaccharides , polymer of~-glucose units which are joined by ~-glycosidic
polysaccharides are carbohydrates in which hundreds linkage between C-1 of one glucose unit and C-4 of next
of molecules of monosaccharides are joined together by glucose unit.
glycosidic linkage. , ,
'Ibey are represented by the general formula (C6H100 5)n
where, the value of n varies from 12 to several hundred.
'lb~se a~e tasteles~ .and are ins~l~ble in water. When
hydrolysed, they change to the monosaccharides. Important
polysaccharides are starch, cellul~se and glycogen. H OH H OH n
• I
Structure of cellulose
(A) Starch (C6H100s>n~ , ,

Starch is a mixture of two components-a water soluble Cellulose is not digestible by human beings since, cellulose
component called amylose (20%) and a water insoluble hydrolysing enzyme, cellulase is absent in human digestive
co!llponent called amylopectin (80%). , , system. However, grazing animals digestive system possess
Amylose cellulase and hence these animals can use cellulose of grass
When hydrolysed, amylose gives a.-D-(+)-glucose. Amylose and plants as food.
consists of long and linear chains of several D-(+)-glucose
(C) Glycogen
units, joined by a.-glycosidic linkage between C1 of one
Glycogen, (C6H 100 5)" is the reserve carbohydrate of the
glucose unit and C4 of the other unit. .
•♦) 6 • '
animals and is stored in liver and muscles. At the time·
• I 6
CHi)H CH2OH of requirement, it gets hydrolysed into glucose which on
~-oH . \ 't • '
oxidation provides energy t? the body.
~o l O"'-"'- Glycogen neither reduces Fehling's solution nor forms
an osazone. Structure of glycogen is similar to that of
H ·OH H OH •. amylopectin but it is more branched than amylop~ctin.
, ~tructure of amylose
Am . . J

ylose gives a violet colour with 12 solution due to the ,

formation of an inclusion complex.
' •

~Key Note
• Testformr6o6Jdlates
- !
._.....,.._.,..,_ J
Atnylopectin
Am 1 ' . . • I
t Molisdnfestis used for the detection offlfl'1Ptof•w,itlflf. 1
Yopectin is highly.branched polysaccharide composed t When Molbdlt INgffff (a 1096 alcoholic solution of a-flaPlllllol) i
~ains of a-D-(+)-glucos_e units joined by a.-glycosidic l 1s added to t11e aqueous solution of a carlJollydrat! followtd bJ i
I.
ge between C-1 of one glucose unit and C-4 of next cone. tfiSOc along the sides of the test ~ aViolet ring Is fanned ·
glucose unit (as in case of amylose). These chains are ~ at the junction of . . ~ whidl Olllfinns the PlmK! " :
connected to each other by 1,6-linkage.
L~.~ - -- . - . I
 8 t'A.tG- JEE Main Ch
ellllstr~

Self Check MC0s ♦

l. Hydrolysis of sucrose gives 1I. Assuming swee~ess of the cane sugar to be Io
(a) two molecules of glucose sweetness of glucose 1s , the
(b) two molecules of fructose (a) 15 (b) 1.5 (c) 12.5 (d) 7.s
(c) one molecule each of glucose and fructose
{d) one molecule each of glucose and mannose.
12• Which of the following reagents cannot d' .
istino,,•
between glucose and ,ructose.?
I.'.
o"lsh
2• Glucose when treated with CH3OH in presence of (a) Tollens' reagent , (b) Fehling's solutio
dry ~Cl gas gives a- and 13-methylglucosides because it (c) Benedict's solution (d) All of these n
contains
13. In polysaccharides, the linkage
(a) an aldehydic group {b) a -CH2OH group connect·1ng
(c) a ring structure monosaccharides is called
{d) five -OH groups. (a) glycoside linkage (b) nucleoside linh
3• Which of the following (c) glycogen linkage (d) · peptide linkage. ge
monosaccharides is a pentose?
{a) Glucose · {b) Fructose
(c) Arabinose (d) Galactose
14. The rapid _inte_rconversion of a.-D-glucose and
glucose in solution 1s known as
a.
D.
4. Table sugar is a (a) racemisation (b) asymmetric inducr
{a) disaccharide of D-glucose and D-fructose . al 1somensm
(c) function . . (d) mutarotation. ion
{b) a monosaccharide
IS. Which of the following is the sweetest sugar?
(c) a disaccharide containing two glucose units
(d) D-glucose. (a) Sucrose (b) Glucose
(c) Fructose (d) Maltose
5. Which of the following does not reduce Benedict's
solution? 16. What happens when dil. H2SO4 is treated with su
1
(a) Oxidation (b) Reduction gar,
(a) Glucose (b) Fructose ·
(c) Sucrose (c) Dehydration · (d) Hydrolysis
(d) Aldehyde
17. Which of the following is a correct statement?
6. For osazone formation, the effective structural unit
necessary is (a) Starch is a polymer of ex-glucose.
(b) Arnylose is a component of cellulose.·
(a) CH2OH (c) Proteins are compounds ofonly one type ofamino acid.
I (d)
co In cyclic structure of fructose, there are four carbons
I and one oxygen atom.
(c) CH2OH (d) CHO 18. Cellulose is a polymer of
I I (a) glucose (b) · fructose
CHOCH3 CHOCH3 (c) ribose (d) sucrose.
I I
7. The change in the optical rotation (with time) of 19. An organic compound with the formula C H 0
6 12 6
freshly prepared solution of sugar is known as ., . forms a yellow crystalline solid with phenylhydrazine and
(a) specific rotation (b) inversion gives a mixture of sorbitol and mannitol when reduced
(c) rotatory motion (d) mutarotation. with sodium. Which among the following could be the
compound? ,
8. When amylase catalyses the hydrolysis of starch, the
(a) Fructose (b) Glucose
final product obtained is chiefly
(c) Mannose (d) Sucrose
(a) cellobiose (b) glucose
(c) maltose (d) sucrose. 20. The disaccharide present in milk is
(a) ' sucrose ·· · · (b) maltose
9. Glucose molecule reacts with X number of molecules
(c) lactose (d) cellobiose.
of phenylhydrazine to yield osazone. The value of Xis
'a) three (b) two 21. The tei:m invert sugar refers to an equimolar mixture
r:) one (d) four. of
(a) D-glucose and D-galactose
?· .Molisch test is answered by (b) D-glucose and D-fructose
j all carbohydrates (b) sucrose (c) D-glucose and D-mannose , .
fructose (d) glucose. (d) D-glucose and D-ribose.
 1ec11/es
91of1'10 .
lucose and ~-D-glucose differ from h
V-G b .h eac othe
ii• ~-difference in one ~ar on wit respect to its r {c) Glucose •
. . rotates plane polarized light in clock-wise
611e to of bemiacetal nng d1rect1on.
(a) si:nber of OH groups (d) Fructos 15
· 'di
e oxi sed by bromine water.
(b) t1 figuration
coll . :~ !~;~~se on reacting with cone.sulphuric acid gives
(c) coJlformation.
(c) mose and S01 (b) glucose and fructose
(d) d Iysis of sucrose is called carbon and water (d) carbon, water and S02.
J-JY ro .
j3• dration (b) ~apondication 32. Glucose HCN HydrolY1is Hl heat
1 A.A is
(a) bY rification (d) inversion. (a) heptanoic acid
este (b) 2-iodohexane
(c) d'ne test is shown by (c) heptane
(d) heptanol.
10 33
iA, ~eptides (b) glycogen j :he two forms of D-glucopyranose obtained from the
01
(a) ~tarch (d) glucose. so uhon of D-glucose are called . ,
(c) (a) isomers (b) anomers
c,,-P(+)-Glucose and ~-D(+)-glucose are (c) epimers (d) enantiomers.
25, enantiomers (b) geometrical isomers
(a) iJllers (d) anomers. 34. Maltose is made ~p of
(c) ep . . , (a) a-D-glucose
fructose gives the silver mirror test because it (b) D-fructose
26• . contains an aldehyde group
(c) a-D-glucose and ~D-glucose
(a~ contains a keto group (d) glucose and fructose.
(b undergoes rearrangement under the alkaline 35. A pair of diastereomers that differ only in the
(c) conditions of the reagent to form a mixture of glucose configuration about a single carbon atom are called
andmannose (a) tautomers (b) epimers
(d) ~.<?ne of the above. (c) conformers (d) enantiomers.
36. Which of the following is an example of ketohexose?
27• It is best to carry out reactions with sugars in neutral or (a) Mannose (b) Galactose
acid medium and not in alkaline medium. Th.is is because
(c) Maltose (d) Fructose
in alkaline medium sugars undergo one of the following
changes 37. Which is not a reducing sugar?
(a) racemisation (b) decomposition (a) Glucose (b) Fructose
(c) inversion (d) rearrangement. (c) Mannose (d) Sucrose
' 38. The monomeric units of starch is/are
28. In lactose, the reducing part is
(a) glucose (b) fructose
(a) galactose (b) glucose
(c) glucose and fructose (d) mannose.
(c) fructose (d) mannose.
39. Which carbohydrate is an essential constituent of
29. Mutarotation does not occur in plant cells? ·
(a) sucrose (b) D-glucose (a) Starch (b) Cellulose
(c) L-glucose (d) none of these. (c) Sucrose (d) Vitamins
30. Which of the following is false? 40. Which polymer is used in making rayon?
(a) Sucrose is a non-reducing sugar. (a) Polyester (b) Nylon
(b) Glucose is oxidised by bromine water. (c) Cellulose (d) Starch

0 .Pr~teins and a-Amino Acids

Proteins have . very high molecular weights and upon NH2
complete hydrolysis they give a-amino acids via peptides. al
1
R-CH-COOH
p • Hydrolysis .• · ' Hydrolysis · · · ·
rotems > Peptides > ex-Amino acids Upon hydrolysis, proteins give only a.-amino acids.
· Amino acids contain both an -NH1 group and a -COOH .The a.-carbon ofall the amino acids (except glycine) is chiral
and hence, amino acids can exist in two stereoisomeric
group. These are classified as a, (3, y, etc. Amino acids in
forms, i.e., D and L.
Which the -NH2 group is attached to the a-carbon atom
with respect to -COOH group are called a-amino acids. Zwitter ion or Dipolar Structure of a-Amino Acids
Their general formula is · Since ex-amino acid molecule has a basic -NH2 group and
~ addi c-CO OH group.a proton trans fertakesplacefro
Wv-tG- JEE Main Che -·
.. ,,stry
macidic
-CO OH group to basic -NH group in the same Isoleucine ;Nl-12
2 molecule (Ile) C2H s-CH -Cli
to form a dipol ar ion or zwitt er ion. I \
0 CH3 COQ}i
II 0
R--C H-C -0-H II e (Essential)
~ R-C H-C -0
I ~
H2N: I ;NH2
H3~ Phenyl alanine (Phe) CJ!sCH2 CH\
lsoelectric Point of a-Amino Acids (Essential) COO H ,
In acidic medium, amin o acid behaves as a cation
and H2C -CH 2
migrates towards catho de while in basic medium,
amino I I
acid behaves as an anion and migrates towards
anode on H2\. /CHC OO} i
passing electric curre nt. Proline (Pro)
H+ N
NHi (:HR Coo - ~ e NHJ :HR C008 I
(Anionic structure) "'OH Dipolar structure H
w + (It does not fit in the general fo uI
' . nn a)
~ NHJ :HRC OOH (ii) Amino Acids with Polar but Neutral Side Chain
· -OH (Catio,nic structure)
However, at some intermediate value of TryptophaI_1(Trp)
1 ,
pH, the
conc entra tion of the cationic form and anion H
ic form N'C H
beco me equal and hence, there is no net migration NH2
of the 11 I
a-am ino acids unde r the influence of an electric C-C H2- CH- COO H
field This
pH is called the isoelectric poin t At this pH, the amin (Essential)
o acid ,
will primarily exist as neutral dipolar ion or zwitter ion. ;NH2
Serine (Ser) HO- CH2-CH
Neutral, Acidic and Basic Amino Acids
Amin o acids which contain one -NH group and \COO H
2 one -
COO H grou p are called neutral amino adds, e.g. ;NH2
glycine, Threonine
alanine, valine. Amino acids which contain one -NH (1hr} · CH3C HOH - CH\
2 group
and two -CO OH grou ps are acid ic in natu (Essential) COOH
re, e.g.,
aspa rtic acid , glut amic acid, etc. Amin ., '
o acids ~ ;NH2
containing two -NH2 groups and one -CO OH Tyrosine (Tyr) H ~ C H2-CH \
grou p are
called basic amino adds. e.g. lysine, histidine, argin 1
ine, etc. C90 H
Essential and Non-Essential Amino Acids
' /NH2
The amin o acids which can be synthesised by the Cysteine
body are (Cys) HS- CH2 -CH
know n as non-essential amino acids while those whic
h the 'coo H
body fails to synthesise are called essential amin
o acids.
These are supplemented by diet. /NH2 ,
Methionine (Met) CH3SCH2C H2CH \ ',
Classification of a-Amino Acids COO H
(Essen tial)
The a -ami no acids are classified into the follow
ing four
types: H2N \ /NH2 ··
(i} Amino Acids with Non-Polar side Chain Aspargine (Asn) CCH 2CH \ ,
, // COOH
/NH2 0
Glycine (Gly) CH2 \
H2N\ , /NH2 ,
COO H
Glutamine (Gin) CCH2CH2CH\
l ;NH 2 // COOH
Alan ine (Ala) 0
CH3 CH\
COO H
(ill) Amino Acids with Acidic Side Chains
/NH 2 /NH2
Valine (Val) (CH 3)iC H-C H\ Aspartic acid (Asp) HOO CCH iCH\
(Essential) COO H COO H
;NH2 ;NH2
Lcucine (Leu) (CH3)iCH -CH 2CH \ Glutamic acid (Glu) HOOCCHiCH CH \
2
(Essential) COO H coo H
 •-- 111 ■ -.Ii

ieeufes .
giOf110 403
• 0 Acids with Basic Side Chains
)
(Ii . .
~"''" ' '
1NH2 ' (B) Oassification on the Basis of Chemical
Composition
(Lys) H2N(CHi)4CH\ .
, 1ys~e (Essential) COOH 1• Simple pr~teins
These proteins on hydrolysis give only a-amino acids, e.g.,
HN
albumin, globulin, glutelin, etc. '
~ NH
(Arg) /CNH(CiiihCH/ 2 2• Conjugated proteins
,Arginine
H}l (Essential) \ COOH Conjugated proteins on hydrolysis give in addition to
a-amino acids a non-protein portion called the prosthetic
NH2 group.
C-CH2-CH / The conjugated proteins are further classified according to
// ""-
HC · NH
\ COOH the nature of the prosthetic group.
Jiistidine (His)
I .• / Name of protein Prosthetic group
' ., ' N~CH (a) Nucleoproteins Nucleic acid
,. ' (Essential) (b) Glycoproteins Sugars (carbohydrates)
,.. . peptides . .
(c) Chrorno proteins pigment having some metals
pepti·des are amides
. formed by co~densation of-NH2 group
like Fe, Cu in haemoglobin
of one i;., ·M..,;n0 acid with-COOH group of the other with
v,•jUJUA• I

.• ation of a molecule ofH20.

··,:... m
· - 3. Derived proteins
the eUJU • R' ., . . These are the proteins formed by the partial hydrolysis of
R I , simple conjugated proteins such as proteoses, peptones,
I ~o
N-CH-COOH + H2N-CH-COOH -4 polypeptides, etc. These proteins may be regarded as
H2 R . ~ intermediate hydrolysis product
I I
HzN-CH-CO-NH-CH-COOH
· Dipeptide . ► Structure of Proteins

The _ co'-
NH - bond ~us formed called the pepti1e is 1. Primary Structure
Primary structure refers to the number, nature and sequence
bond or the peptide linkage. . _.. of amino acids pres~nt in a protein molecule.
Normally, N-terminal amino acid residue (having the free
2. Secondary Structure
amino group) is written at the left and C-terrninal amino·
Secondary structure refers to the conformation which the
acid at the right. polypeptide chains assume as a result of H-bonding. There
Peptides ai-e generally classified as' dip~ptides, tripeptides... are two types of secondary structures :
polypeptides, etc. accordingly as they contain two, three or (a) a-Helix: In this type of protein, polypeptide chains
a large number (hundreds to thousands) of peptide bonds. coil up to form a spiral-like structure. There o~curs
Relatively shorter peptides are called oligopeptides. extensive intermolecular hydrogen bonding between
two adjacent turns so that the helix is rigid.
► Proteins and ,their Classification I
(b) ~Flat sheet or ~Pleated sheet structure : In this
Polypeptides with molecular mass more than 10000 are structure polypeptide chains are extended and held
normally called proteins. together by intermolecular hychogen bond. •
(A) On the Basis of Molecular Structure · . 3. Tertiary Structure
Proteins are classified as fibrous and globular proteins.' Tertiary structure refers to the three dimensional structure
- of proteins. It explains the way, the molecule folds to
· Fibrous proteins ' · Globular proteins produce a specific shape. ·
1. Consist ·of linear L Polypeptide chains are 4. Quaternary Structure
polypeptide chains folded and stabilised by It describes the arrangement and ways in which different
held by H-bonds intramolecular hydrogen sub units are held together.
bonds ► Denaturation of Proteins
2. Insoluble in water
...._ Most of the soluble globular proteins when heated are
2. Soluble in water
3. Stable to changes in coagulated to insoluble fibrous proteins. This coagulation
3. Sensitive to small changes of proteins is called denaturaHon. Coagulation can also be
pH and temperature in pH and temperature caused by treating proteins with strong acids or bases or
e.g., keratin (in hair) e.g., enzymes, hormones strong electrolytes.
fibr_o in (in silk), (insulin), antibodies,
- myosin (in muscles) haemoglobin.
The denaturation causes a change in the secondary and
tertiary structures of proteins. However, the primary
 404 rrt.-tG- JEE Main Che.....
•111stry

structure remains intact. e.g. coagulation of albumins The enzyme protein without its prosthetic group .
present in the white of an egg, when the egg is boiled hard anoenzyme and is catalytically inactive. With the pr ish the
r
group, it is known as the holoenzyme. ost ertc
and formation of cheese from milk on adding lemon juice
when the globular milk protein, lactalbumin becomes Holoenzyme ~ Apoenzyrne + Cofactor
fibrous. (conJ'ugated protein) (Protein) (Prosthetic g
roup)
Denaturation results in loss of biological activity. In case of Prosthetic group attached to the enzyme
few denatured proteins if temperature and pH are brought . . protei
(apoenzyme) may be regarded as d1ssoc1able port· n
back to original conditions, then biological activity as well conjugated proteins. If the prosthetic group or cot: ion of
as secondary and tertiary structure of protein is recovered. . . b . 1actor i
a non-protemaceous organic su stance, 1t is regard d s
This reverse process is called renaturation ofproteins. co-enzyme. Cofactors may also include some metat i as
► Tests of Proteins also like Zn2+, Mg2• , Fe2• , Na+, K+, Cu2•, etc. ons
1. BiuretTest Efficiency of Enzymes
On adding few drops of copper sulphate solution to an Enzymes are very efficient catalysts. They speed u
alkaline solution of protein, a bluish violet colour develops. rate of bio-reactions by a factor upto 1020 • Efficien: ~e
This test is basically for peptide linkage. catalyst/enzyme is measu,red in terms of turn over nu,n~ a
2. Millon's Test The turn over number of an enzyme refers to the nu,n;'·
-
Proteins give a white precipitate with Millon's base which of molecules of a substance acted upon by one mole
of enzyme per minute. Enzyme activity is temperature cu:
7
changes to red upon heating. Millon's reagent is prepared
by dissolving an equal amount of mercuric and mercurous pH sensitive. They show maximum efficiency at an optim:i
nitrate in distilled water. pH (6-7.7) and temperature (15-40°C) range.
3. Ninhydrin Test Enzyme Inhibitors
Protein and a -amino acids give a blue or violet colour These are the chemical substances which tend to reduce
with ninhydrin (2, 2-indane-1,2,3-trione). · the activity of a particular enzyme. Such substances are
4.
called enzyme inhibitors. These are mostly the inorganic
Molisch's Test •
ions or the complex organic molecules. A few examples of
To an alcoholic solution of a-naphthol and protein
the enzyme inhibitors are : salts of heavy metals, cyanide
concentrated sulphuric acid is added dropwise. A violet
ion, DNP (dinitrophenyl hydrazine), DFP (diisopropyl
colour develops at the junction of the liquids. This test is
fluorophosphate). · ·
given by proteins which contain a carbohydrate residue.
This is also a test for the presence of carbohydrates. Enzyme Deficiency
Certain diseases are caused by the deficiency of enzymes.
~ Key Note i[ -----..-----..------....- The congenital disease phenylketone urea is caused by
• All the a-amino adds forming proteins have £-configuration while all deficiency of enzyme phenylalanine hydroxylase while
the naturally occurring ca~rates have D-configuration. albinism is caused by deficiency of enzyme tyrosinase.
The enzyme streptokinase is used to dissolve the blood clot
► Enzymes formed in coronary artery, which may lead to heart attack.
Enzymes are often referred as bio-catalysts. They catalyse Specificity of Enzymes
reactions that are taking place in the body. Enzymes are specific in their reaction :'
Chemical Nature of Enzymes Proteolytic enzymes i.e., enzymes involved in protein
Chemically all enzymes are proteins and are also sometimes digestion hydrolyse proteins to a-amino acids. e.g.
known as protein-catalysts. Some enzymes are simple pepsin, trypsin, chymotrypsin, etc. .
proteins while the others are conjugated proteins and their Maltase, lactase, amylase hydrolyse maltose, lactose
molecules consist of amino acids and non-proteinous part. and starch to glucose. .
which is known as prosthetic group. The prosthetic group Nuclease hydrolyses DNA and RNA to nucleotides.
is essential for catalytic activity and is termed as co-factor. Urease converts urea to CO2 and ~H3, etc.

Self Check MC(Yls ♦

J. The bond tha't determines the secondary structure of a (a) formation of amino acids ' I

protein is (b) loss of primary structure

(a) coordinate bond (b) covalent bond (c) loss of both primary and secondary structure
(c) hydrogen bond (d) ionic bond. (d) loss of both secondary and tertiary structure.
2 Denaturation of proteins leads to loss of its biological 3. On ·heating with cone. HN03, proteins give yellow
activity by colour. This test is called '
r
,eeufes
giO,r,o 405
. ·ng test (b) xanthoproteic test
·d1Sb• 3
o-P 's test (d) acid-base test. .
(•) flopPe ~ • Violet colour is obtained when dilute CuSO4 is added
man alkaline 1 .
(C) P structure of protein refers to (a) B' so ut1on of protein. This test is known as
1
5econdarYdnatured proteins and structure ofprosthet· uret test (b) Xanthoproteic test
4. aiJllY e , 1c (c) Hopkins-cole test (d) Millon's test
(a) i1l ups ·
gro .dimensional . struc~re, especially the bond l4. Which of the following is correct?
"') tbfee amino acid residues that are distant fro (a) C'.cloheptane is an aromatic compound.
iv berweethn in the polypeptide chain m (b) Diastase is an enzyme.
chO er (c) Acetophenone is an ether.
ea quence of amino acid residues in the
lillear se . (d) All of these.
(c) eptide chain . .
polypar folding patterns of contmuous portions of the lS, In an amino acid, the carboxyl group ionises at
(d) re~eptide chain. · ~K., = 2.34 and ammonium ion at pK. = 9.60. The
2
Po isoelectric point of the amino acid is at pH
wiuch of the £ll · cherruc·a1 units
o owmg · 1s· certainly to
(a} 5.97 (b) 2.34 (c) 9.60 (d) 6.97
S, d in an enzyme?
1,efoun 16. Which of the following is not an amino acid?
~O\ N~ (a) Glycine (b) Alanine

(a)
' ~ - ~ - (b)
I:10 HO O
l.)
N
(c) Histidine (d} Benzidine

\
17. The pH value of the solution in which a particular
0 ,' amino acid does not migrate under the influence of an
M electric field is called the

to ~~
(a) eutectic point (b) yielding point ,
H 0 (c) neutralisation point (d) isoelectric point
(c) I II ' (d)
0/V'\.R
-N-C- 0 18. Which of the following is a proteolytic enzyme?
(a) Insulin (b) Diastase
OMR (c) Pepsin (d) Adenine
6. Which of the following is a specific test for proteins? 19. Which compound can exist in a dipolar (zwitter ion)_
(a) Beilstein test (b) Biuret test structure?
' (c) Benedict's test (d) Molisch test =
(a) C6H5CH2CH (N CHJCOOH
7, In the conversion of sucrose to glucose, the enzyme is (b) (CH3)zCHCH(NH2)COOH
(a) zymase (b) lipase· (c) C6H5CONHCH2COOH
(c) invertase (d) ~astase: (d) HOOCCH2CH2COCOOH

8, Which of the following enzymes is not useful in the 20. The structural feature which distinguishes praline
digestion of proteins? from other natural ex-amino acids?
(a) Chymotrypsin (a) It is optically inactive
(b) Pepsin
(c) Trypsin (b) It contains aromatic group
(d) Lipase
(c) It contains two amino groups
9, Enzymes are essential as biocatalysts. They function in (d) It is a secondary amine
(a) aqueous medium, temperature = 30-35 °C; pH= 7
21. Which statement is incorrect about pepti~e bond?
(b) organic medium
(a) C-N bond length in proteins is longer than usual bond
(c) aqueous medium under extreme pH conditions length of C-N bond. '
(d) none of these.
(b) Spectroscopic analysis shows planar structure of
lO. lhe prosthetic group present in glycoproteins is - C-NH-bond.
(a) nucleic acid _ · (b) phosphoric acid II
0
(c) lipid ' · · ' (d) carbohydrate. ·.
(c) C-N bond length in proteins is smaller than usual
11 bond length of C-N bond.
· Which amino acid is achiral ?
(a) Alanine (b) Valine (d) None of these.
(c) Histidine (d) None of the above 22.
Of the following statements about enzymes, which
l2 - - . .
· lack of essential amino acids in the diet leads to the ones are true?
disease . (i) Enzymes lack in nucleophilic groups.

\ i:: :•blindness
L...__ shiorko,
(b) pernicious anaemia
(d) sickd cell anaemia.
(ii) Enzymes are highly specific both in binding chiral
substrates and in catalysing their reactions.
 "'-tG- JEE Main Ch
el'llistry
(iii) Enzymes catalyse chemical reactions by lowering the 26. The enzyme pepsin hydrolyses
energy of activation. , (a) proteins to amino acids
(iv) Pepsin is proteolyic enzyme. (b) fats to fatty acids
(a) (i) and (iv) (b) (i) and (iii) (c) glucose to ethyl alcohol
(c) (ii), (iii) and (iv) (d) (i) only (d) polysaccharides to monosaccharides.
23. At the isoelectric point, amino acids are present as 27. Enzymes
(a) H2N - CHR- COOH (b) H3N+ - CHR - COOH (a) have optimum activity at body temperature
(c) NH2 - CHR - coo- (d) H3N+ - CHR - COO-. (b) consists of nucleic acids
24. The relation of the isoelectric point for an amino acid, (c) are carbohydrates
to solubility is . (d) have all these properties.
(a) the two are not related 28. Which one of the following is not a protein? , ,
(b) an amino acid is least soluble at its isoelectric point (a) Wool (b) Nail
(c) an amino acid has the maximum solubility at the
(c) Hair (d) DNA
isoelectric point
(d) solubilities of only some amino acids depend on it. 29. The main structural feature of proteins is
25. Which of the following represents a peptide chain?
(a) ester linkage (b) ether linkage
(c) peptide linkage (d) all of these.
H
I I 30. Which is not a true statement?
(a) -N-C-N-C-NH-C-NH -
11 I I II (a) ex-Carbon ofa-amino acid is asymmetric except gl .
0 H O . (b) All proteins are found in L-form. YCine.
H H (c) Human body can synthesise all proteins they need
I I I I I I I I I
(b) -N-C-C-C-C-N-C-C -C-C- (d) At pH= 7 both amino and carboxylic groups exist,
11 I I I I I I I the ionised form. m
0

Ir I I f
(c) -N-C-C-N-C-C-N-C -C-
r R
31. The number of amino acids found in proteins that a
human body can synthesize is
(a) 20 (b) 10 (c) 5 (d) 14 ' 1
1 II I II I
0 0 32. Which of the following is not a function of proteins?
H H (a) Nail formation
I I I I I I I (b) Skin formation
t I
(d) -N-C-C-C-N-C-C-N- C-C-C- (c) Muscle formation
I •

1 I II I I I I 11 I I
, 0 H H 0 (d) Providing energy for metabolism

() Other Biomolecules .
,, • I ,

► Vitamins
A vitamin is an organic compound required in tiny amounts for essential metabolic reactions in a living organism.
They cannot be made by the organisms and so have to be supplied in the diet. Their deficiency causes many diseases,
There are about 25 vitamins known. They are broadly divided into two categories : ·
1. Fat soluble vitamins : Vitamin-A, D, E and K. ' '· · ··
2. Water soluble vitamins : Vitamin-B1, Bi, B6, B12 and C.
Vitamin name Chemical name Solubility Sources Deficiency disease I

Vitamin A Retinoids Fat Mill<, butter, eggs, fish, cod liver Night-blindness, Xerophthalmi~:
(retinol, retinoids oil, green vegetables. It can also
and carotenoids) be synthesised in body from ~ 'I . :·; . , I ,I

carotenoids present in carrots, • I t

tomatoes, mangoes etc. '
VitaminB1 Thiamine Water Pulses, nuts, cereals (rice, Beri-beri, loss_of appetite. , '
wheat, etc.), rice bran, yeast, ~

egg yolk, fruits and green : \

, I;
vegetables, etc.
··-···-······· -----····------- -- •·•--· ... ..............................--······ ·-········· . .....................................................
...... --
lilll
 fecufes
~O,r,O
··············. . ................ 407
.--~"ii;······ ..Riboflavin
•'\fit ·w~ ~;; ;-~ ~-~ -~-~";j~~;;r-.;;~-;;;-.;;-
~
Pantothenic acid Water Pean meat, hver, kidney, etc. dermatitis, cheilosis
¢t
uts,
produ ts avocado dairy D titi
erma s
etc. c ' eggs, whole grains

~ Niacin Water Meat, legumes, .

~ Product, fish etc. dairy
Pyridoxine Water Pellagra
vitaJllill Rice
bran, whole cereal
(wheat, gram), yeast, fish, Affects central nervous system,
meat, eggs, etc. causes weakness, convulsions,
~
Biotin Water insomnia, anaemia.
Folic acid Water Milk. Yeast, liver, kidney. Dermatitis
~iJ1B 9 . Green vegetables, soyabean, '
kidneys. Deficiency during pregnancy is
Cyanocobalamine Water associated with birth defects.
vitaJJlin B12 Egg, milk, liver of ox, sheep, Perniciou
fish, etc. s anaemia
Ascorbic acid
~c Water Citrus fruits (e.g.
orange, Pyorrhea, scurvy (bleeding of
' lemon, am1a, grape fruits, etc.), gums)
chillies, sprouted pulses, etc.
~D(a Ergocalciferol and Fat
·cholecalciferol Butter, milk, eggs, fish liver oil, .Rickets (bending of bones) and
Jll,iJhll'e li~er and meat Vitamin D is
3 osteomalacia.
ofvitaJlllllS produced in skin in presence
D &03) of sunlight
\TitaJDlllE .. Tocopherol Fat Wheat germ oil, milk, nuts Loss of fertility in males, muscle
p
' peanut oil, cotton seed oil, degeneration.
egg, fish, etc.
waroin K Phylloquinone Fat Leafy vegetables like cabbage, Haemorrhage and lengthens the
- spinach, etc.
1 time of blood clotting. I

► Nucleic Acids ' 0

N5I
Nucleic acids are biomolecules which are found in the
nuclei of all living cells in form of n~cleopr~teins. Th~y
are biopolymers in which the repeating structural unit or
monomeric unit is a nucleotide. That is why nucleic acids
are also called polynucleotides. These are required for the
OJ__N
H
Cytosine (C)
·. oV N
H
Uracil (U)
storage and expression of genetic information.
Each nucleotide consists of three components : Nucleosides and Nucleotides
1. A pentose sugar, i.e., D(-)-ribose or 2-deoxy-D(-)- Nucleosides contain only two components : a pentose sugar
and a nitrogenous base. ·
ribose. Both these sugars are found in, the furanose
form. Nucleotides contain all the thre·e components : a pentose
2. A heterocyclic nitrogenous base. a
sugar, nitrogenous base and a p~osphoric_acid group.
Two types of nitrogenous bases are pr~sent in nucleic Types of.~.ucleic Acids .
acid. i.e. purines and pyrimidines. Depending upon the type of sugar present, nucleic acids
Purines include : Adenine (A) and Guanine (G). are of two types, DNA and RNA.
Pyrimidines include : U~acil (U), Thymine (T) and Deoxyribonud~c add Ribonucleic add
Cytosine (C). (DNA) (RNA)
3. Phosphoric acid. 1. Occurs in the nucleus of Occurs ~ the cytoplasm
the cell

N~N
~NI J
rrCH, {Q
.O.J_N
0 0 2. Sugar present is 2-deoxy- Sugar present is D-(-)-
D-(-)-ribose · ribose
3. Contains cytosine and Contains cytosine and
I thymine . as pyrimidine uracil as p~din e
H2NA N
H H bases, guanine and bases and guarune and
Adenine (A) H
Thymine(T) adenine as purine bases adenine as purine
Guanine(G)
-- - ----·--· ------------------- --------------- bases
 t'A.tG- JEE Main Ch .
408 ern,stry
th template (or pattern) for the synthesis of tw
--- --------------------------- -------- ----------------
Single-stranded c:x-helix
as e . o new
4. Double-stranded ex-helix strands of DNA.
structure structure Protein synthesis occurs in two steps, i.e., transc . .
5. Undergoes replication Does not undergo . r1pt1on
and translation.
replication Transcription is the process of synthesis of RNA..
Structure of DNA (Double helix structure) The synthesis of proteins occurs in the cytoplasm
On the basis of X-ray analysis of DNA, J.D. Watson and cell. The m-RNA directs protein synthesis With th of the
· called tran e •help
. process 1s
F.H.C. Crick (shared Nobel Prize in 1962) proposed a three ofr-RNA and t-RNA. Th1s s1at ,._ 10
dimensional secondary structure for DNA. DNA molecule is a
Genetic Code
long and highly complex, spirally twisted, double helix, ladder
Linear sequence of tlµ'ee nucleotides (triplets) in DN
like structure. The two polynucleotide chains or strands are · th "fi · A. or
RNA that determmes . e ~pec1 c ammo ~cid sequence .
linked by hydrogen bonding between the nitrogenous base
the synthesis of.proteins 1~ called genetic code. It is th~
molecules of their nucleotide monomers. Hence, the two
biochemical basis of heredity and nearly universal in all
strands extend in opposite directions, i.e., are antiparallel
and complimentary. organisms.
Mutation
Mutation may be defined as a change in nitrogenous b ·
sequence of DNA molecule which leads to the synthesis~;
proteins with an altered sequence of amino acids. Mutatio
· n

~l
may cause genetic disorders or diseases.
~--~
I~ Key Note r- · - . . .,. - - .. - -- .....-·~ ".
' '

• Uplels -· . ... . •.. ., : ·

These are "waxy or oily esters of long-chain fatty acids" and ~~
present In all living organisms. Their main function is to store energy
for the cell. Lipids are insoluble in wat~~ and soluble in organic!'
solvents 6ke carbon tetrachloride, chloroform and ether. •···" .- ,
• Oassification of Uplds - . -· · - - :...
(A) Simple Uplds . · . . .. , j
Simple lipids are esters of fatty acids with alcohols and indu~e: "!l
(I) Triglycerides : Triglycerides are the triesters of glycerol with·
unbranched and long chain fatty acids. The triglycerides may be'
either oils or fats In nature. The oils contain large proportion of the
1
unsaturated esters while the fats mainly contain saturated adds.·
(ii) Waxes : Waxes are the esters of long chain fatty adds
Chargaff's Rule (between C14and CJ with long chain monohydric alcohols(between
The rule describes base composition of a DNA molecule. It t C16 and CJ, I.e., Bees wax, (myricyl palmltate), Camauba wax
states that amount of purine bases is always equal to that I· (myricyl cerotate), and Spermaceti (cetyl palmitate). · ·
of pyrimidine bases. Purine base of one strand of DNA I (B) Compound or conjugated lipids .
molecule pairs with pyrimdine base of the other strand. These are the heteroliplds which contain other functional groups In
Adenine (A) pairs with thymine (T) through two H-bonds
(A= T) and guanine (G) pairs with cytosine (C) through
three H-bonds (G =
In case ofRNA, adenine
C)
(A) pairs with uracil (U),
·'
(A= U).
II addition to esters. These include : - ' ·- . ·
(I) Glya,llplds : There are lipids conjugated with carbohydrates_
e.g., cephalin. These are amphipathk and form bilayer In water.
· (U) · Upoprotelns : These are the lipids bound to proteins found
1
Biological Functions of Nucleic Acids I Inthe blood plasma. They may be chylomiaons, Beta-llpoprotelns,]
Two important biological functions of nucleic acids are : ! Alpha-llpoprotelns. ·· ~
replication and protein synthesis. ( 01I) Phosphollplds : The additional group in these lipids indude]
Replication t phosp!wnc acid, nitrogen containing bases and other su~ts.j
e.g., ledthln present In eggs. , ·. . ~
Replication may be de.fined as : the process by which a
single DNA molecule produces two identical copies ofitself. (() Derived Upkls . . : . . .
Replication is an enzyme catalysed process and starts with These are obtained by hydrolysis of simple and compound Upids.
the partial unwinding of double helix structure through
breaking of the hydrogen bonds. Each strand then acts
__ __
These indude fatty adds, fatty alcohols,·mono and dlglycerides.'
..__ steroids,
__.terpenes and carotenolds. ·
 fecufes
8i0,r,O
. ~--;~ . when exposedtoalrlnthin layers, formha~d
• p,yl;ugh water insoluble solids. This prpcess Is known as dr,ln,
and h oils are called drying oils. e.g., linseed oil tung oil perm
Ir unsatii;i;s Is the on or fat It~ defined as ~mbe r of grams of l
. lod'me that WIR combine With 100 gof the oil or fat. In general, drying \
and sue . • . . ' ' a \ oils have high Iodine values, non-drying oils have low iodine values l
od, etc. ~Us contain a high ~erce~tage of 'unsa~rated .trlg~~rldes)
prying linoleic acid and hnolenic acid as the unsaturated fatty~~
containing · ·· ' · · ·· .
f .while semi drying offs have intermediate values.
!• a...-. " - are blomolecules which are produced
i the ductless (endocrine) glands and are carried to different parts 111 of
Ii

· residues. umber orvalue. Iodine number Is a m~asure of the extent } ~ body by the blood SIJeam where 111,j colllJul rutouo mela~'.k·1
1odtne nration present in an oil or fat Higher the Iodine value, more I Pfocesses. These are required In small amount and are not stored in
otunsatu~.---- . ........_ t..,.,, ~~butarecontinuouslyproduced. , . ..., •. , • , *
0' rtant hormo nes along with the sources and functi
so-...e i.JllP . ' .1 . ons are summarised as follows :
· Name · • . •· . · · Organ of c:--.......
. ·· .
-11:Uo n · Functions
I. Steroidal hormones
sex hormo nes Testes
1 Control primary and secondary sexual characteristics
· ·(a) Androgens . 'u
in males.
_Male sex hormo nes, e.g.
(.Androsterone and Testosterone) _

(b) Estrogens Ovary

Control primary and secondary sexual characteristics
female sex hormo nes, e.g.
in females.
(Estr~ne, Estradiol, Estriol)
(c) Gestogens Corpus luteum Contro ls the develo pment and mainte nance of
Pregnancy hormo nes, e.g.
pregnancy.
(Progesterone)
2. Adrenal cortex hormo nes Adrenal cortex Regula te the metabo lism of fats, protein s and
(Cortisone, Cortico sterone
carbohydrates; control the balanc e of water and
Aldosterone, etc.) ,
minerals in the body.
II. Peptide (Non-steroid) hormo nes
(a) Insulin . Pancreas Controls the metabolism of carbohydrates, mainta ins
glucose level in the blood.
(b) Oxytoc in Posterior lobe of Contro ls the contrac tion of the uterus after child
(Nanop eptide hormo ne) pituitary gland birth and produc e lactatio n in mamm ary glands.
(c) Vasopressin Posterior lobe of Contro ls the reabsor ption of water in kidneys.
(Nanop eptide hormo ne) I I
pituitary gland
(d) Angiot ensin-l I Blood plasma of
(Octap eptide hormo ne)
Potent vasoco nstrict or i:e. contra cts the blood
persons with high vessels.
• I ,
blood pressure
I •• J III. Amine (Non-steroid) hormo nes
(a) Adrena line or Epinep hrine Adrenal ~edull a It prepares animals and humans for emergency act in
many ~ays by raising the pulse rate: blood pressure,
etc.; stimula tes the breakd own of liver glycogen
.. , into blood glucose and fats into fatty acids du.ring
emergency.
(b) Thyrox ine Controls metabolism of carbohydrates, lipids and
Thyroid gland
proteins.