BIOMOLECULES PRESENTATION class xii.pptx

BIOMOLECULES
Biomolecules are produced by living organisms
Examples:Carbohydrates, proteins,nuceic acids,
lipids etc.Proteins and carbohydrates are
essential constituents of our food.
These biomolecules interact with each other and
constitute the molecular logic of life processes.
Some simple molecules like vitamins and mineral
salts play an important role in the functions of
organisms

DENATURATION OF PROTEINS
• When a protein in its native form is subjected
to physical change like change in
temperatureor chemical change like change in
pH the hydrogen bonds are disturbed . Due to
this,globules unfold and the helix get uncoiled
and protein loses its biological activity. This is
called denaturation of protein.During
denaturation 20
and 30
structures are
destroyed and 10
structure remains intact.

• Ex:The coagulation of egg white on boiling ,
curdling of milk due to the formation of lactic
acid by the bacteria present in milk.
• Enzymes:These are also called biocatalysts and
are globular proteins. Enzymes are very specific
for a particular reaction and for a particular
substrate.They are named after the compound
upon which they work.For ex the enzyme
maltase hydrolyses maltose in to glucose.

CARBOHYDRATES
• These are produced by plants and form a very large group of
naturally occuring organic compounds.EX: Cane sugar,
glucose, starch etc. The name carbohydrate means hydrates
of cabon and most of them have a general formula Cx (H2 O)y
• The molecular formula of glucose C6 H12 O6 fits into this
general formula, C6 (H2 O)6 . But all other compounds which
fit into this formula may not be classified as carbohydrates.
For ex: CH3 COOH is not a carbohydrate which fits in to the
formula as C2 (H2 O)2 . Similarly rhamnose C6 H12 O5 is a
carbohydarte but does not fit in this definition.

• Carbohydrates may be defined as optically active poly hydroxy
aldehydes or ketones or the compounds which produce such
units on hydrolysis.The carbohydrates which are sweet in taste
are also called sugars.ex: sucrose and lactose (present in milk)
• Carbohydrates are also called saccharides (Greek: sakcharon
means sugar)

Classification of Carbohydrates on the basis of
behaviour towards hydolysis
• (i)Monosaccharides: A carbohydrate that cannot be hydrolysed
further to give simpler unit of poly hydroxy aldehyde or ketone is
called a monosaccharide. Examples are glucose, fructose, ribose etc .
• (ii)Oligo saccharides: Carbohydrates that give two to ten
monosaccharide units on hydrolysisare called oligosaccharides .They
are further classified as disaccharides,
trisaccharides,tetrasaccharides, etc ., depending upon the no of
monosaccharides they provide on hydrolysis. The two
monosaccharide units obtained on hydrolysis of a disaccharide may
be same or different.
• For ex sucrose on hydrolysis gives one molecule each of glucose and
fructose where as maltose gives two molecules of glucose only

POLY SACCHARIDES
• Carbohydrates which yield a large no of
monosaccharide units on hydrolysis are called
polysaccharides .Examples are starch, cellulose,glycogen ,
gums etc. Polysaccharides are not sweet in taste , hence
they are also called non-sugars.
• The carbohydrates may also be classified as either
reducing or non- reducing sugars. All those carbohydrates
which reduce Fehling’s solution and Tollen’s reagent are
referred to as reducing sugars.All monosaccharides
whether aldose or ketose are reducing sugars.

• In disaccharides if the reducing groups of
monosaccharides i.e., aldehydic or ketonic groups are
bonded, these are non-reducing sugars e.g sucrose. Sugars in
which these functional groups are free , are called reducing
sugars, for example maltose and lactose.

MONOSACCHARIDES
• Monosaccharides are further classified on
the basis of no. Of carbon atoms and
functional group present in them.
• If a monosaccharide contains an aldehydic
group it is known as an aldose and if it
contains a keto group it is known as a ketose.

PREPARATION OF GLUCOSE
• Cane sugar : Glucose occurs freely in nature as
well as in the combined form. It is present in
sweet fruits and honey.Ripe grapesalso contain
glucose in large amounts.
• Preparation of glucose:
• 1. From sucrose(cane sugar): If sucrose is boiled
with HCl or H2 SO4 in alcoholic solution,glucose
and fructose are obtained in equal amounts.

• C12 H12 O11 + H2 O C6 H12 O6 + C6 H12 O6
suarose glucose fructose
• 2. From starch: Glucose is obtained by
hydrolysis of starch by boiling it with dilute
H2 SO4 at 393K under pressure.
(C6H10O5 )n + n H2 O nC6H12O6
Starch or cellulose glucose

STRUCTURE OF GLUCOSE
• Glucose is an aldohexose and is also known
as dextrose. It is the monomer of many of the
larger carbohydrates, namely starch, cellulose.
It is the most abundant organic compound on
earth.
• Structure of glucose:

EVIDENCES FOR THE STRUCTURE
• 1.Its molecular formula is C6 H12 O6 .
• 2. On prolonged heating with HI, it forms n-
hexane , suggesting all the six carbons are
linked in straight line

• 3.Glucose reacts with hydroxyl amine to form
an oxime and adds a molecule of HCN to give
cyanohydrin, confirms the presence of a
carbonyl group(<C=O) in glucose.

• 4. Glucose is oxidised to gluconic acid on
reaction with a mild oxidising agent like Br2
water indicating that the carbonyl group is
present as an aldehydic group.

ACETYLATION OF GLUCOSE WITH ACETIC ANHYDRIDE
• It gives glucose pentaacetate which confirms
the presence of five –OH groups and they
should be attached to different carbon atoms.

OXIDATION WITH HNO3
• Glucose as well as gluconic acid both give a
dicarboxylic acid , saccharic acid ,indicates the
presence of a 10
alcoholic(-OH) group in
glucose.

FISCHER FORMULA
• The exact spatial arrangement of different -OH
• groups given by Fischer represented as I
below. Gluconic acid and saccharic acid are
represented by II and III below respectively

• Glucose is named as D(+) –glucose where
‘D’ represents configuration and (+) represents
dextrorotatory nature of the molecule. ‘D’ and
‘L’ have no relation with the optical activity of
the compound and they indicate the relative
configuration of a particular isomer of
glyceraldehydes , which contains one
asymmetric carbon atom and exists in two
enantiomeric forms as shown below.

• All those compounds which are chemically
correlated to (+) isomer of glyceraldehyde are
said to have D-configuration where as those
related to (-) isomer are said to have L-
configuration. The structure of glucose is
compared to glyceraldehyde w.r.to the
position of –OH group present on the lowest
asymmetric carbon as given below.

Cyclic structure of glucose
• The structure I of glucose explained most of its
properties but the following reactions could not be
explained by this structure.
• 1.Glucose does not give Schiff’s test and
hydrogensulphite addition product with NaHSO3
despite having the aldehyde group.
• 2. The pentaacetate of glucose does not react with
hydroxylamine indicating the absence of free –CHO
group.
•

• 3. The inter conversion of α and ß could not be
explained by open chain structure I for gluose
since one of the –OH groups may add to the –
CHO group and form a cyclic hemiacetal
structure and glucose forms a six membered ring
in which –OH at C-5 is involved in ring formation
which explains the absence of –CHO group and
also existence of glucose in two forms which
exist in equilibrium with open chain structure.

• These two forms differ only in The
configuration of the –OH group at C-1 called
anomeric carbon and are called anomers. The
six membered cyclic structure of glucose is
called pyranose structure (α or ß ). Pyron is
acyclic organic compound with one oxygen
atom and five carbon atoms in the ring.

THE CYCLIC STRUCTURE OF GLUCOSE
• Haworth structure as given below

FRUCTOSE
• It is an important ketohexose obtained by the
hydrolysis of sucrose. Fructose contains a keto
group at C-2 and six carbons in straight line
like glucose and denoted by D-(-) fructose. Its
open chain structure is as shown in the fig

• It also exists in two cyclic forms which are
obtained by the addition of –OH at C5 to the
(>=O) group. The ring formed is a five
membered ring known as furanose as furan is
a five membered cyclic compound with one
oxygen and four carbon atoms.

The cyclic structures of two anomers of fructose
are represented by Haworth structures as
given.

DISACCHARIDES
• Glycosidic linkage: A linkage between two
monosaccharide units through oxygen by
losing a molecule of water is called glycosidic
linkage.
• (i)Sucrose : It on hydrolysis gives equimolar
mixture of D-(+)-glucose and D-(-)fructose.
• C12 H22 O11 + H2 O → C6 H12 O6 + C6 H12 O6
• sucrose D-(+) glucose D-(-)fructose

• By a glycosidic linkage between C1 of α- glucose
and and C2 of β-fructose. As the reducing
groups of glucose and fructose are involved in
glycosidic bond formation , sucrose is a non-
reducing sugar
• Invert sugar: Hydrolysis of sugar brings about a
change in the sign of rotation , from dextro (+) to
laevo(-) and the productis named as invert sugar
and this process is known as inversion of sugar

• Maltose : Composed of two α-D-glucose units
in which C1 of one unit is linked to C4 of of
another glucose unit.The free aldehyde group
can be produced at C1 of second glucose in
solution and it shows reducing properties so it
is a reducing sugar.

• Lactose : It is found in milk known as milk
sugar composed of β-D-galactose and β-D-
glucose . The linkage is between C1 of
galactose and C4 of glucose. Hence it is a
reducing sugar.

STARCH
• Starch is a homopolysaccharide, polymer of glucose.
• It is a reserve food material in plants-potatoes, rice, wheat etc.
• Starch consists of two parts
a) AMYLOSE (15%-30%)-a linear, unbranched polymer of glucose
and water soluble. ALL THE GLUCOSE MOLECULES ARE
LINKED BY ɑ(1→4) GLYCOSIDIC BONDS .

Amylopectin is insoluble in water and
constitutes about 80-85% of starch. It is a
branched chain polymer of α-D- glucose units

Cellulose
It occurs in plants and most abundant organic substance in plant kingdom.It
constitutes cell wall of plant cells.Composed of beta –dD-glucose units.

Glycogen
• The carbohydrates are stored in animal body as glycogen.also
known as animal starch because its structure is similar to
amylopectin and is highly branched It is present in liver,
muscles and brain. When the body needs glucose , enzymes
break the glycogen down to glucose. Glycogen is also found in
yeast and fungi. Importance of carbohydrates : Carbohydrates
are essential for life both in plants and animals. They form a
major portion of our body. These are used as storage molecules
as starch in plants and glycogen in animals. Cell wall of bacteria
is made up of cellulose. Funiture from cellulose in the form of
wood and clothes in the form of cotton.They provide raw
materials for many industries.

AMINO ACIDS
Amino acids are organic molecules, derivatves of methane.
One hydrogen atom is replaced by amino (-nh2) group,
second one is replaced by carboxylic acid (-cooh) group and
the third one is replaced by aliphatic or aromatic side
chains(r) and the fourth remains unaltered.
Each amino acid has a polarity i.E., One side has nh2 (amino
or n) terminal and the other side has cooh (carboxylic or c)
terminal
ALPHA CARBON ATOM

HOW MANY AMINO ACIDS ARE THERE?
There are 20 amino acids present in proteins, therefore these
are called proteinogenic or standard amino acids.
Of the 20 some cannot be synthesized by ones body, must be
supplied through the food, hence are called essential amino
acids.
Some can be synthesized by ones body, hence are called
non-essential amino acids.

ESSENTIAL AMINO
ACIDS
NON-ESSENTIAL
AMINO ACIDS
PHENYL ALANINE ALANINE
VALINE ASPARTIC ACID
THREONINE ASPARAGINE
TRYPTOPHAN ARGININE*
ISOLEUCINE CYSTEINE
METHIONINE GLYCINE
HISTIDINE GLUTAMIC ACID
ARGININE* GLUTAMINE
LEUCINE PROLINE
LYSINE SERINE
TYROSINE
* ESSENTIAL IN CHILDREN * NON ESSENTIAL IN ADULTS

PROPERTIES OF AMINO ACIDS
1. Amino acids are zwitter ions or hybrid ions. That means when they are
dissolved in aqueous medium, they undergo ionization and possess both positive
and negative charges.
2. Amino acids are amphoteric. That means they behave both acids as well as bases
in alkaline and acidic medium respectively.
3. In alkaline medium they donate proton(h+ ion), gain negative charge and behave
as acids.
4. In acidic medium they accept proton(h+ ion), gain positive charge and behave as
base
BASE ACID
ZWITTER ION
ACID MEDIUM ALKALINE MEDIUM
NEUTRAL MEDIUM

CLASSIFICATION OF AMINO ACIDS BASED
ON CHARGES
NEUTRAL

Classification of Amino acids
• Amio acids are classified as acidic , basic, or neutral
depending upon the relative no.of amino and carboxyl groups
in their molecule. Equal no.makes it neutral, more amino
makes it basic and more carboxyls makes it acidic .
• Non- essential amino acids: Which are synthesized in the
body.
• Essential amino acids :Those which can not be synthesized in
the body and must be obtained through diet.

PEPTIDE BOND
When two amino acids undergo condensation they lose a molecule of water (dehydration)
and jion together with the help of a bond called peptide bond ( co-nh). And the resultant
molecule is called dipeptide.
Therefore a dipeptide contains two amino acids and one peptide bond, a tripeptide will
have three amino acids and two peptide bonds, n peptide (polypeptide) will have n number
of amino acids and n-1 peptide bonds respectively.
DIPEPTIDE
PEPTIDE BOND 1PEPTIDE BOND 2

PROTEINS
The term protein was derived from greek word proteios, meaning
prime importance.
The trem given by sweedish biochemist jons jocob berzelius in
1838.
Proteins are macromolecule and are the polymers of amino acids.
These are hetero polymers, that is made up of different
arrangement of hundreds and thousands of 20 standard amino
acids just like 26 letters of english make words, sentences,
paragraphs etc.
The amino acids in proteins are linked by peptide bonds. The
polymeric chain of amino acids is also called as polypeptide chain.

STRUCTURE OF PROTEINS
The native proteins undergo three dimensional
conformation modifications to become more stable and
efficient.
Depending upon their structural modifications there are
4 types of protein structures.
01. Primary structure ( primary proteins)
02. Secondary structure ( secondary proteins)
03. Tertiary structure (tertiary proteins)
04. Quaternary structure (quaternary proteins)

Four Levels of Protein Structure

Four Levels of Protein Structure
Primary Structure: Is a linear chain of amino
acids.
N-terminal
C-terminal
EXAMPLE FOR
PRIMARY
PROTEINS
INSULIN

AMYLOPECTIN (70%-85%)
AMYLOPECTIN IS ALSO A POLYMER OF GLUCOSE LINKED BY
ɑ(1→4) GLYCOSIDIC BONDS
IT IS A BRANCHED POLYMER. Branching occures at every 24-30
glucose units.
At branchings the linkage is ɑ(1→6) glycosidic bonds.
It is insoluble in water

CELLULOSE
• IT IS A LINEAR, UNBRANCHED POLYMER OF Β,d-glucose UNITS. ALL THE
GLUCOSE MOLECULES ARE LINKED BY Β(1→4) GLYCOSIDIC BONDS .
• It Is A Fibrous Molecule And The Chief Structural Component Of Cell Wall Of Plant
Cells.

NUCLEIC ACIDS
Nucleic acids are the biopolymers, or large
biomolecules, essential to all known forms of life. The
term nucleic acid is the overall name for dna and rna.
They are composed of nucleotides, which are the
monomers made of three components: a 5-carbon sugar,
a phosphate group and a nitrogenous base.
If the sugar is a compound ribose, the polymer is rna
(ribonucleic acid); if the sugar is derived from ribose as
deoxyribose, the polymer is dna (deoxyribonucleic acid).

DNA contains four bases A,G,C,and T. RNA also contains four bases, the
first three bases are same as in DNA but the fourth one is uracil(U)

Double Strand helix structure for DNA

THERE ARE TWO TYPES OF NUCLEIC ACIDS
RNA AND DNA
RNA
NITROGENOUS
BASES
PURINE
BASES
PYRIMIDI
NE
BASES
URACIL
CYTOSINE
PENTOSE SUGAR(C5H10O5)
PHOSPHORIC ACID(H3PO4)

THERE ARE TWO TYPES OF NUCLEIC ACIDS
RNA AND DNA
DNA
NITROGENOUS
BASES
PURINE
BASES
PYRIMIDI
NE
BASES
THYMINE
CYTOSINE
PENTOSE SUGAR(C5H10O4)
PHOSPHORIC ACID(H3PO4)
H

• C12 H22 O11 → 2C6 H12 O6
• Maltose glucose
• Mechanism of enzyme action : Enzymes are needed only in small quantities for
the progress of a reaction. Enzymes reduce the magnitude of activation
energy.For ex activation energy for acid hydrolysis of sucrose is 6.22 KJ mol
-
1
,while the activation enrgy is only 2.15 Kjmol-1
when hydrolysed by the
enzyme sucrase.

Vitamins
• Certain organic compounds which ae required in small
amounts in our diet but their deficiency causes specific
diseases are called vitamins. These perform specific
biological functions for normal maintenance of optimum
growth and health of the organisms. Vitamins are
designated by alphabets A,B,C,D etc .and some are
further named as sub-groups e.g B1 ,B2 , B6 , B12
etc.Excess vitamins is also hrmful and vitamin pills
should not be taken without the advice of doctor.

Classification of vitamins
• Vitamins are classified into two groups depending opon their
solubility in water or fat.
• (i)Fat soluble vitamins : Vitamins which are soluble in fat and
oils but insoluble in water.Ex: Vitamins A, D, E, K .
• (ii) Water soluble vitamins : B group vitamins and vitamin C
are soluble in water and these must be supplied regularly in
diet because they are readily excreted in urine and can not be
stored (except vitamin B12 ) in our body.

BIOMOLECULES PRESENTATION class xii.pptx

BIOMOLECULES PRESENTATION class xii.pptx

More Related Content

Similar to BIOMOLECULES PRESENTATION class xii.pptx

Recently uploaded

BIOMOLECULES PRESENTATION class xii.pptx

Editor's Notes