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Macromolecules
Chapter5: The Structure and
function of Biomolecules
Learning objectives: At the end of this
chapter you should be able to explain
4 classes of macromolecules
 Polymers ,monomers, synthesis &breakdown
 carbohydrates:definition, monosaccharides,
Disachharides & Polysaccharides with
examples. Glycosidic bond , α & β
configuration
 Glycogen , starch ,cellulose & chitin. –its
monomers, structure and function
Chapter5: The Structure and
function of Biomolecules
Lipids : Triacylglycerol,saturated fatty acid, Phospholipids,
steroids.
Proteins: amino acid ,peptide bond, Four levels of protein
structure, Primary structure, secondary structure, tertiary
structure & quaternary structure.
Protein denaturation , chaperonin ,.
Nucleic acids: Nucleotide monomers, (Nitrogen base &
monosaccharides), Polynucleotide chain, structure of DNA
double helix.
Chapter5: The Structure and
function of Biomolecules
Chapter5: The Structure and
function of Biomolecules
Characteristics of Living
Organisms.

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First is their Degree of chemical
complexity and Organisation.
Living organisms extract, transform and
use energy from their surroundings.
Capacity for precise self replication and
self assembly
Chapter5: The Structure and
function of Biomolecules

Life is an organized genetic unit capable of
metabolism, reproduction and evolution.
Chapter5: The Structure and
function of Biomolecules
Biochemical Unity underlies
Biodiversity in all cells.
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Organisms are uniform at the
molecular level.
DNA & genetic code is common in all.
Chapter5: The Structure and
function of Biomolecules
Macromolecules
Chapter5: The Structure and
function of Biomolecules
BIOMOLECULES
(MACROMOLECULES)
INORGANIC
-
-
WATER
CO2
O2
INORGANIC
SALTS Na+, K+,
Mg2+, Ca2+, Cl-,
HCO3- SO42-, PO33-
-
ORGANIC
CARBOHYDRATES
PROTEINS
LIPIDS
NUCLEIC ACIDS
Chapter5: The Structure and
function of Biomolecules
Biomolecules

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Biomolecules are compounds of carbon.
Carbon forms single bonds with H, double
bonds with oxygen and Nitrogen atoms.
Each carbon can form single, double or
triple bonds with carbon.
Carbon can form linear , branched and
cyclic structures.
Chapter5: The Structure and
function of Biomolecules
Macromolecules.
Macromolecules
are
giant polymers
built by the covalent linking of smaller units
called monomers.
Chapter5: The Structure and
function of Biomolecules
Macromolecules perform functions such
as
-Energy storage,
-structural support,
-information storage,
-transport ,
-defennse.

Chapter5: The Structure and
function of Biomolecules
• Proteins
• Carbohydrates
• Nucleic acid.
• Lipids
Chapter5: The Structure and
function of Biomolecules
Carbohydrates

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Aldehyde or ketone compounds with
multiple hydroxyl groups.
Energy stores, fuels &metabolic
intermediates
Structural framework.
Structural elements in the cell wall of
bacteria & plants.
Linked to many proteins & lipids.
Chapter5: The Structure and
Functional groups.
To carbon skeletons groups of other
atoms called functional groups are
added.
Hydroxyl group
Chapter5: The Structure and
function of Biomolecules
Carbonyl group
Aldehyde group
Ketone group
Chapter5: The Structure and
function of Biomolecules
Carbohydrates
Monosaccharides.
Disaccharides.
Polysaccharides.
Chapter5: The Structure and
function of Biomolecules
Monosaccarides- simple sugars
(C-H2O)n, where n= 3,4,5,6,7
Monosaccharides containing an aldehyde group
are called aldoses.
Monosaccharides containing a ketone group are
called ketoses.
Monsaccharides based on n carbon
atoms : triose,tetrose,pentose ,hexose,
heptose
Chapter5: The Structure and
function of Biomolecules
GLUCOSE - C6H12O6

is an aldohexose with
the formula (C·H2O)6.

C -1 contains the
aldehyde group.
Chapter5: The Structure and
function of Biomolecules
Ring Structure of Glucose
6
Monosaccharides form a
Six membered ring called
Pyranoses.

5
1
4
333
33
33
2
Chapter5: The Structure and
function of Biomolecules
Anomers
α & β forms . ( position of hydroxyl group
in c-1 In the ring form).
Chapter5: The Structure and
function of Biomolecules
Epimer of Glucose
C-4 atom
C-4
atom
Chapter5: The Structure and
function of Biomolecules
Ketose sugar
Dihydroxyacetone Ketotriose
Fructose:
Ketohexose
FOUND IN
FRUITS,
honey
Chapter5: The Structure and
function of Biomolecules
Disaccharides
Two monosaccharides joined by a
glycosidic
Linkage,
a covalent bond
formed between two monosaccharides by a
dehydration reaction.
Dehydration
reaction
reaction) -----?
Chapter5: The Structure and
function of Biomolecules
(condensation
Dehydration reaction
A condensation or Dehydration
reaction links monomers into
polymers
and
releases a molecule of water for each
bond formed.
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Chapter5: The Structure and
function of Biomolecules
Dehydration reaction
Disaccharides are
linked by
glycosidic
linkages.
Disaccharides –Maltose
Maltose (Malt sugar)
Two glucose molecules
Linked by 1-4 glycosidic
Linkages
Chapter5: The Structure and
function of Biomolecules
Malted barley
Sucrose -table sugar
Glucose and Fructose :
glycosidic linkage.
Chapter5: The Structure and
function of Biomolecules
1-2
Lactose –Milk Sugar
Lactose: Glucose and Galactose.
Chapter5: The Structure and
function of Biomolecules
Hydrolysis (break with water)

Reverse of dehydration reaction
Hydrolysis digests polymers and produces
Monomers.
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The hydrolysis of sucrose yields -----and ----
Chapter5: The Structure and
function of Biomolecules

A dehydration reaction joins two glucose
molecules to form maltose. The formula
for glucose is C6 H12 O6. what is the
formula for maltose?
Chapter5: The Structure and
function of Biomolecules
Polysaccharides.

are polymers of monosaccharide units
connected by glycosidic linkages.
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Storage polysachharide ex: starch

Structural polysachharide. Ex: cellulose.
Chapter5: The Structure and
function of Biomolecules
starch
Starch is a polysaccharide of alpha
glucose .
-is a storage polysaccharide ( energy
store) found in plants.
Chapter5: The Structure and
function of Biomolecules
Two forms
Amylose
:
:
Amylose & Amylopectin
linear polymer of α glucose linked
by 1-4 linkage.
Amylopectin - Branched
Polymer
polymer of α glucose.
Contains α 1,6 branches in addition to α 1,
4 bonds between glucose units.
Chapter5: The Structure and
function of Biomolecules
Glycogen
storage polysaccharide of animal cells. (stored
in liver and muscle cells)
Glycogen is a polymer of α Glucose
Highly branched .(every 10 to 12 glucose
units.)
Chapter5: The Structure and
function of Biomolecules
Chapter5: The Structure and
function of Biomolecules
Structural Polysaccharide
Cellulose
linear Polymer of
Glucose in β
configuration.
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Unbranched polymer.
Hydrogen bond
between cellulose
molecules
Chapter5: The Structure and
function of Biomolecules
Cellulose
Each glucose is upside down
Chapter5: The Structure and
function of Biomolecules
Chitin
– Structural polysaccharide
Monomer is modified
sugar at C-2(Nitrogen
appendage)
Exoskeleton of
arthropods and molluscs.
Chapter5: The Structure and
function of Biomolecules
2
2
Comparison of
cellulose
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????
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monomers and
Configuration
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Structure
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Functional role
Glycogen & Starch
? ????
Chapter5: The Structure and
function of Biomolecules
Celluose in β
linkages is not
hydrolysed in
humans
Ruminants &
termites can
digest help of
symbiotic microorganisms that live
in their gut
Chapter5: The Structure and
function of Biomolecules
CARBOHYDRATES: Compounds composed of Carbon, Hydrogen and
Oxygen. General formula (CH2O)n.
They are polyhydroxy aldehydes or ketones. They include sugars
and polymers of sugar
Monosaccharide:
Disaccharides:
POLYMERS: are long molecules consisting of many similar or
identical building blocks linked by covalent bonds. (Monomers)
Monomers are connected by a reaction – condensation/
Dehydration reaction.
Carbohydrates
MONOSACCHARIDES
Glucose
Galactose
Ribose
Glyceraldehydes
Fructose
Ribulose
Dihydroxyacetone
DISACCHARIDES
Maltose
Lactose
Sucrose
Chapter5: The Structure and
function of Biomolecules
POLYSACCARIDES
Starch
Glycogen
Cellulose
Chitine
Nucleic Acids
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o
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Found in animal viruses or DNA viruses,
prokaryotes, plasmids, eukaryotic nucleus
and organelles like chloroplast and
mitochondria.
Nucleotides are the building blocks of DNA and RNA
are composed of a sugar, a phosphate,
and a base.
Nucleotides : Building blocks of
Nucleic Acids
Nitrogen bases:
Purines: Double ring
Adenine and
Gunanine
Pyrimidines: Single
ring
Cytosine
Thymine
And Uracil.

Components of a
NUCLEOTIDE:
Pentose sugar : In
DNA Deoxyribose sugar
or
RNA Ribose Sugar
NUCLEOSIDE - Sugar and
a nitrogen base forms
nucleoside
Nucleotide : Phosphate
group attached to a
nucleoside is nucleotide
1
2

Polynucleotides:
Polymer of
nucleotides.
Adjacent nucleotides are
joined by covalent
bonds called
phosphodiester
bond - bond between
OH group of 3’ carbon
and Phosphate group
of 5’ Carbon
.
Structure of the DNA molecule:
1 .Two polynucleotide chains are coiled around a
common axis.
2. Specific base pairing of the nitrogen bases.
Adenine =Thymine (by 2 hydrogen bonds )
and Guanine = Cytosine (by 3 hydrogen bonds)
3. Two chains are antiparallel or definite
polarity.
4. Two strands are complementary to each
other
H
N
N
N
N
Sugar
O
H
H
CH3
N
N
N
AdeAdenine
O
Sugar
Thymine (T)
H
O
N
N
Sugar
N
H
N
N
N
N
N
H
Figure 16.8
H
Guanine (G)
H
O
Sugar
Cytosine (C)
Sugar phosphate forms the backbone of the helix.
- nitrogen bases are located on the inside of the helix.
3ᶦ
5ᶦ
5ᶦ
3ᶦ
5ᶦ

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Diameter- 20A
one turn of the helix – 34 A
adjacent base pairs-3.4 A
Stability of the helix:
Due to hydrogen bonding and base
stacking
RNA

In RNA
Aldo Pentose Sugar
is : Ribose
Nitrogen Base:
Pyrimidine base:
Thymine is replaced by
Uracil.
RNA is single stranded.