class 11biology ch-9

1. Submitted to: Meenakshi Ma’am
Submitted by: Kunal Singh Shekhawat, Kuldeep Singh Rathore

2. INTRODUCTION
 Biomolecule - is molecule that is present in
living organisms, including large macromolecules such
as proteins, carbohydrates, lipids, and nucleic acids, as
well as small molecules such as
primary metabolites, secondary metabolites, and natural
products.
 Most biomolecules are organic compounds, and just
made up of four elements—oxygen, carbon, hydrogen,
and nitrogen—make up 96% of the human body's mass.

3. AMINO ACIDS
 Amino acids are organic compounds containing amine (-NH2)
and carboxyl (-COOH) functional groups, along with a side chain
(R-group) specific to each amino acid.
 Key elements of an amino acid are:
carbon, hydrogen, oxygen, and nitrogen, apart from other
elements found in the side chains of certain amino acids.
 They can be classified according to the core structural functional
groups' locations as alpha- (α-), beta- (β-), gamma- (γ-) or delta-
(δ-) amino acid.

4.  Based on the nature of R group there are many types of amino
acids.
 The R group could be hydrogen(glycine), a methyl(alanine),
hydroxy methyl group(serine).
 Based on the number of amino and carboxyl groups there are
acidic(glutamic acids),basic(lysine) and neutral(valine).

5. IMPORTANCE OF AMINO ACIDS
 Amino acids are the building blocks of Protein.
 Approx. 20% of the human body is made up of protein, and
it is vital in almost all biological processes.
 Important Role :
 in the transport and the storage of nutrients,
 influencing the function of organs, glands, tendons and
arteries.
 essential for healing wounds and repairing tissue,
especially in muscles, bones, skin and hair.
 needed for the removal of all kinds of waste deposits
produced in connection with the metabolism.

6. LIPIDS AND FATTY ACIDS
 Lipid is a loosely defined term for substances of biological origin
that are soluble in nonpolar solvents. It comprises a group of naturally
occurring molecules that include fats, waxes, sterols, fat-
soluble vitamins (such as vitamins A, D, E, and k), monoglycerides,
diglycerides, triglycerides, phospholipids, and others.
 Fatty acids has an R group. The R group could be a methyl(-CH3),
ethyl
(-C2H5) or higher number of-CH2 group.
 They are made up of hydrocarbon chain that terminates with a
carboxylic acid group, this arrangement confers the molecule with a
polar, hydrophilic end and a non polar, hydrophobic end that is
insoluble in water.

8.  Fatty acids can be saturated or unsaturated. A saturated fat is a
type of fat in which the fatty acids all have single bonds. An
unsaturated fat is a type of fat in which fatty acids all have
double or triple bonds.
 The chains of carbon atoms that are on the same side of the
double bond, resulting in a kink is called a cis fatty acids,
whereas, the chains of atoms that are on the opposite sides are
called trans fatty acids.
 Fatty acids can be fats or oils based on their melting and
boiling point. They can be monoglycerides, diglycerides or
triglycerides.
 Some lipids have phosphorus in them and so these are called
phospholipids. They are found in the cell membrane e.g-
lecithin.

10. IMPORTANCE OF FATTY ACIDS
 Fatty acids are important dietary sources of fuel
for animals because, when metabolized, they
yield large quantities of ATP. Many cell types can
use either glucose or fatty acids for this purpose.

11. NUCLEOTIDES
 Nucleotides are organic molecules that serve as the monomer
units for forming the nucleic acid polymers DNA (deoxyribonucleic
acid) and RNA (ribonucleic acid).
 They are composed of three subunit molecules: a nitrogenous base,
a five-carbon sugar (ribose or deoxyribose), and at least
one phosphate group. They are also known
as phosphate nucleotides.
 There are four different DNA nucleotides, each with one of the four
nitrogen bases(adenine, thymine, cytosine and guanine).
Purines and Pyrimidines are nitrogenous bases that make up the
two different kinds of nucleotide bases in DNA and RNA.
 The two-carbon nitrogen ring bases (adenine and guanine) are
purines, while the one-carbon nitrogen ring bases (thymine and
cytosine) are pyrimidines.

13. NUCLEOSIDES
 Nucleosides are glycosylamines that can be thought
of as nucleotides without a phosphate group. A
nucleoside consists simply of a nucleobase (also
termed a nitrogenous base) and a five-carbon sugar
(either ribose or deoxyribose).
 Examples of nucleosides include cytidine, uridine,
adenosine, guanosine, thymidine and inosine.

15. MACROMOLECULES
TYPES

16. PROTEINS
 Proteins are large biomolecules, or macromolecules,
consisting of one or more long chains of amino acid residues.
 Proteins differ from one another primarily in their sequence
of amino acids, which is dictated by the nucleotide
sequence of their genes, and which usually results in protein
folding into a specific three-dimensional structure that
determines its activity.
 A linear chain of amino acid residues is called a polypeptide.
A protein contains at least one long polypeptide. Short
polypeptides, containing less than 20–30 residues, are rarely
considered to be proteins and are commonly called peptide,
or sometimes oligopeptides.

17. A homopolymer is a polymer having only one type of amino
acid, whereas, a heteropolymer has more than one type of amino
acids.
E.g- proteins.
 Example of proteins:-
Collagen:- it is the most abundant protein in animal world.
Ribulose biophosphate carboxylase – oxygenase:- it is the
most abundant protein in the biosphere.

19. FUNCTIONS OF PROTEINS
 Repair and Maintenance
•Protein is termed the building block of the body. It is called this
because protein is vital in the maintenance of body tissue, including
development and repair. Hair, skin, eyes, muscles and organs are all
made from protein.
 Energy
•Protein is a major source of energy. If you consume more protein
than you need for body tissue maintenance and other necessary
functions, your body will use it for energy. If it is not needed due to
sufficient intake of other energy sources such as carbohydrates, the
protein will be used to create fat and becomes part of fat cells.
 Hormones
• Protein is involved in the creation of some hormones. These
substances help control body functions that involve the interaction
of several organs. Insulin, a small protein, is an example of a
hormone that regulates blood sugar. It involves the interaction of
organs such as the pancreas and the liver.

20.  Secretin, is another example of a protein hormone. This
substance assists in the digestive process by stimulating the
pancreas and the intestine to create necessary digestive juices.
 Enzymes
Enzymes are proteins that increase the rate of chemical reactions
in the body. In fact, most of the necessary chemical reactions in the
body would not efficiently proceed without enzymes.
 Transportation and Storage of Molecules
Protein is a major element in transportation of certain molecules.
For example, hemoglobin is a protein that transports oxygen
throughout the body. Protein is also sometimes used to store
certain molecules. Ferritin is an example of a protein that
combines with iron for storage in the liver.
 Proteins also act as antibodies

21. POLYSACCHARIDES
 Polysaccharides are polymeric carbohydrate molecules
composed of long chains of monosaccharide units bound together
by glycosidic linkages and on hydrolysis give the
constituent monosaccharides or oligosaccharides.
 When all the monosaccharides in a polysaccharide are the same
type, the polysaccharide is called
a homopolysaccharide or homoglycan, but when more than one
type of monosaccharide is present they are
called heteropolysaccharides or heteroglycans.
 Natural saccharides are generally of simple carbohydrates
called monosaccharides with general formula
(CH2O)n where n is three or more.

22.  Examples of monosaccharides are glucose, fructose,
and glyceraldehyde. Polysaccharides, meanwhile, have a
general formula of Cx(H2O)y where x is usually a large
number between 200 and 2500.
 Examples include storage polysaccharides such
as starch and glycogen, and structural polysaccharides
such as cellulose and chitin.
 Examples of monosaccharides
include glucose (dextrose), fructose (leyulose)
and galactose.

24. FUNCTIONS OF POLYSACCHARIDES
 Polysaccharides generally perform one of two
functions:-
energy storage or structural support. Starch and
glycogen are highly compact polymers that are
used for energy storage. Cellulose and chitin are
linear polymers that are used for structural support
in plants and animals respectively.

25. NUCLEIC ACID
 Nucleic acids are biopolymers, or large biomolecules,
essential to all known forms of life.
 They are composed of monomers, which are nucleotides made
of three components: a 5-carbon sugar, a phosphate group,
and a nitrogen base.
 If the sugar is a simple ribose,
the polymer is RNA (ribonucleic acid); if the sugar is derived
from ribose as deoxyribose, the polymer
is DNA (deoxyribonucleic acid).
 Nucleic acid are linear polymers(chain) of nucleotides.
Adenine, cytosine and guanine are found in both RNA and
DNA, while thymine occurs in DNA and uracil occurs in
RNA.

27. STUCTURE OF AMINO ACIDS
 Proteins are polymers — specifically polypeptides —
formed from sequences of amino acids, the monomers of
the polymer.
 Proteins form by amino acids undergoing condensation
reactions, in which the amino acids lose one water
molecule per reaction in order to attach to one another with
a peptide bond.
 By convention, a chain under 30 amino acids is often
identified as a peptide, rather than a protein.

29. PRIMARY STRUCTURE
 The primary structure of a protein refers to the linear sequence of
amino acids in the polypeptide chain.
 The primary structure is held together by covalent bonds such
as peptide bonds, which are made during the process of protein
biosynthesis.
 The two ends of the polypeptide chain are referred to as
the carboxyl terminus (C-terminus) and the amino terminus (N-
terminus) based on the nature of the free group on each extremity.
 Counting of residues always starts at the N-terminal end (NH2-
group), which is the end where the amino group is not involved in
a peptide bond.
 The primary structure of a protein is determined by the gene
coresponding to the protein.

31. SECONDARY STRUCTURE
 Other regions of a protein thread are folded into other forms in
what is called the secondary structure.
 The hydrogen in the amino group(NH2) and the oxygen in the
carboxyl group(COOH) of each amino acid can hydrogen bond
with each other, this means that the amino acid in the same chain
can interact with each other. As a result , the protein chain can fold
up on itself, and it fold up in two ways, resulting in two secondary
structure: it can either wrap round forming the a-helix, or it can
fold on top of itself forming the B-sheet.
 Two main types of secondary structure, the a-helix and the B-
sheet, were suggested in 1951 by linus pauling and coworker.

33. TERTIARY STRUCTURE
 The long protein chain is folded upon itself like a
woolen ball, giving rise to the tertiary structure.
 Tertiary structure refers to the three-dimensional
structure.

35. QUATERNARY STRUCTURE
 Quaternary structure is a three dimensional structure of a subunit
protein and how the subunit fit together.
 Complexes of two or more polypeptides (i.e. multiple subunits)
are called multimers. Specifically it would be called a dimer if it
contains two subunits, a trimer if it contains three subunits,
a tetramer if it contains four subunits, and a pentamer if it
contains five subunits.
 Multimers made up of identical subunits are referred to with a
prefix of "homo-" (e.g. a homotetramer) and those made up of
different subunits are referred to with a prefix of "hetero-", for
example, a heterotetramer, such as the two alpha and two beta
chains of hemoglobin. Adult human hemoglobin consist of 4
subunits.

37. NATURE OF BOND LINKING MONOMERS
IN A POLYMER
 A polypeptide or a protein, amino acids are linked by a
peptide bond which is formed when the carboxyl(-cooh)
group of one amino with the amino(-nh3) group of the
next amino acid.
 In chemistry, a glycosidic bond or glycosidic linkage is a
type of covalent bond that joins a carbohydrate (sugar)
molecule to another group, which may or may not be
another carbohydrate.

39.  A single nucleic acid strand is a phosphate-pentose polymer with
purine and pyrimidine bases as side group.
 A phosphodiester bond occurs when exactly two of the hydroxyl
groups in phosphoric acid react with hydroxyl groups on other
molecules to form two ester bonds.
 The bond between the phosphate and hydroxyl group of sugar is
an ester bond.
 DNA molecules consist of two biopolymer strands coiled around
each other to form a double helix. The two DNA strands are
termed polynucleotides since they are composed of
simpler monomer units called nucleotides.
 The nucleotides are joined to one another in a chain by covalent
bonds between the sugar of one nucleotide and the phosphate of
the next, resulting in an alternating sugar-phosphate backbone.

40.  The nitrogenous bases of the two separate polynucleotide
strands are bound together, according to base
pairing rules (A with T, and C with G), with hydrogen
bonds to make double-stranded DNA.
 There are 2 hydrogen bond between A and T and 3
hydrogen bond between G and C.

45. METABOLISM
 Metabolism is the set of life-sustaining chemical
transformations within the cells of living organisms.
 The three main purposes of metabolism are the conversion of
food/fuel to energy to run cellular processes, the conversion of
food/fuel to building blocks for proteins, lipids, nucleic acids, and
some carbohydrates, and the elimination of nitrogenous wastes
 Metabolism is usually divided into two categories: catabolism,
the breaking down of organic matter for example, the breaking
down of glucose to pyruvate, by cellular respiration,
and anabolism, the building up of components of cells such
as proteins and nucleic acids. Usually, breaking down
releases energy and building up consumes energy.
 Enzymes are crucial to metabolism because they allow organisms
to drive desirable reactions that require energy that will not occur
by

46.  themselves, by coupling them to spontaneous reactions that release
energy. Enzymes act as catalysts that allow the reactions to proceed
more rapidly. Enzymes also allow the regulation of metabolic
pathways in response to changes in the cell's environment or
to signals from other cells.
 The metabolic system of a particular organism determines which
substances it will find nutritious and which poisonous. For example,
some prokaryotes use hydrogen sulfide as a nutrient, yet this gas is
poisonous to animals.
 The speed of metabolism, the metabolic rate, influences how much
food an organism will require, and also affects how it is able to
obtain that food.
 Each metabolic reactions result in the transformation of
biomolecules. Examples are :-
• Removal of CO2 from amino acids making an amino acid n
amine .
• Hydrolysis of a glycosidic bond in a disaccharide.

47.  Metabolites are the intermediates and products of metabolism.
The term metabolite is usually restricted to small molecules.
Metabolites have various functions, including fuel, structure,
signaling, stimulatory and inhibitory effects on enzymes,
catalytic activity of their own (usually as a cofactor to an
enzyme), defense, and interactions with other organisms
(e.g. pigments, odorants, and pheromones).
 Feature of metabolic reactions is that every chemical is a
catalysed reaction. Catalysis is the increase in the rate of
chemical reaction due to catalyst, which is not consumed in the
catalysed reaction. Proteins eith catalytic power are known as
enzymes.

48. ENZYMES
 Enzymes are macromolecular biological catalysts. Enzymes
accelerate chemical reactions. Almost all enzymes are proteins.
 Almost all metabolic processes in the cell need enzymes in
order to occur at rates fast enough to sustain life. The set of
enzymes made in a cell determines which metabolic
pathways occur in that cell.
 The molecules upon which enzymes may act are
called substrates and the enzyme converts the substrates into
different molecules known as products.
 Enzymes get damaged at high temperature. Enzymes isolated
from organisms who normally live in high temperature are
stable and retain their catalytic power even at high
temperatures.

49. STRUCTURE OF ENZYMES
 Enzymes are generally globular proteins, acting alone or in
larger complexes. The sequence of the amino acids specifies
the structure which in turn determines the catalytic activity
of the enzyme.
 Enzyme structures unfold (denature) when heated or
exposed to chemical denaturants and this disruption to the
structure typically causes a loss of activity.
 Enzyme denaturation is normally linked to temperatures
above a species' normal level; as a result, enzymes from
bacteria living in volcanic environments such as hot
springs are prized by industrial users for their ability to
function at high temperatures, allowing enzyme-catalysed
reactions to be operated at a very high rate.

50. FUNCTIONING OF ENZYMES
 In biology, the active site is the region of an enzyme where
substrate molecules bind and undergo a chemical reaction. The
active site consists of residues that form temporary bonds with
the substrate(binding site) and residues that catalyse a reaction
of the substrate(catalytic site).
 To explain the observed specificity of enzymes, in 1894 Emil
Fischer proposed that both the enzyme and the substrate
possess specific complementary geometric shapes that fit
exactly into one another. This is often referred to as "the lock
and key" model.

53. DIFFERENCES B/W ENZYMES
& INORGANIC CATALYSTS
ENZYMES INORGANICCATALYSTS
All enzymesareproteins& have complex
molecularorganisation
Usuallysmall& simplemolecules
An enzymecatalysesonlyaspecific reaction Theycancatalyseano.of reactions,hence
arenot specificforany1 reaction
Enzyme actioncanberegulatedbyspecific
molecules
Cannotberegulatedbyanyothermolecule
Thesearemoresensitiveto changesin pH&
tempof medium
Theyarev.lessaffected bychangesin pH&
tempof medium

54. CLASSIFICATION OF ENZYMES
• CLASS 1: OXIDOREDUCTASES
• Catalyseoxidation/reductionof a substance
• Cytochromeoxidaseoxidises cytochromes
• Glycolateoxidaseoxidises glycolate
Sreduced+S’oxidised Soxidised+S’reduced

55. CLASS 2 : TRANSFERASES
• Theycatalysetransferof specificgroupsfrom1
substrateto another
• Glutamatepyruvate transaminase
• S – G + S’ S + S’-G

56. CLASS 3 : HYDROLASES
• Catalysebreakdownof largermoleculesinto smaller
moleculeswith addition of H2O
Amylasehydrolasesstarch

57. CLASS 4 : LYASES
• Catalysecleavageof specificcovalentbonds&
removalof specificgroups, without the useof H2O
Histidine decarboxylasecleaveshistidine into histamine
& CO2
X Y
C– C X– Y +C= C

58. CLASS 5 : ISOMERASES
• Catalyserearrangementof atomsin amoleculeto
form isomers
• Phosphohexoseisomeraseconvertsglucose6-
phosphateinto fructose -6-phosphate

59. CLASS 6 : LIGASES
• Catalyse covalent bonding b/w 2 substrates to form a
large molecule, mostly involving utilisation of energy
byhydrolysisof ATP
RuBP carboxylasecatalysesthe joiningof RuBP& CO2
in photosyntheticCfixation

60. FACTORSAFFECTING ENZYME
ACTION
• Temperature

61. • Effect ofpH

62. • Effect of substrateconcentration

63. • Effects of chemicals
When bindingof achemicalreduces/ shuts off the enzyme
activity, the chemicaliscalled inhibitor.
INHIBITORS
COMPETITIVE
When inhibitor closely resembles substrate
in molecular structure & binds to active site
of enzyme
NON-COMPETITIVE
When inhibitor does not compete
with substrate for activesite

64. • Feed back inhibition: E n z y m e a c t i v i t y is inhibited
b y p rd t of s a m e e n z y m e reaction
GLUCOSE-6-PHOSPHATE
INHIBITS ACTION OFHEXOKINASE
CATALYSES
PHOSPHORYLATION OFGLUCOSE

65. • Co-factors
ENZYMES
SIMPLE ENZYMES CONJUGATEENZYMES
Madeof 1/severalpolypeptide Hasnon-proteinmoiety+polypeptide chain

66. COFACTOR
PROSTHETICGROUP COENZYME METALIONS
TIGHTLY BOUND
TOAPOENZYME
BOUND TO
APOENZYME DURING
COURSEOFCATALYSIS
METAL IONS FORM CO-
ORDINATION BONDS
WITH SIDE CHAIN AT
ACTIVE SITE OF
ENZYME &SUBSTRATE
HAEM NAD &NADP Zn