DAY TEN
Biomolecules
and Enzymes
Learning & Revision for the Day
u Metabolites u Proteins u Nucleic Acids
u Biomolecules u Lipids u Enzymes
u Carbohydrates
Chemicals or molecules present in the living organisms are essential for the maintenance
of their physiological processes. These are known as biomolecules. These include large
molecules like proteins, nucleic acids, polysaccharides, lipids and small molecules like
metabolites.
Mineral Elements and Their Functions in the Body
Element Percentage Function
Oxygen 65% Cellular respiration and component of water.
Carbon 18% Backbone of organic molecules.
Hydrogen 9.5% Electron carrier, component of water and most organic molecules.
Nitrogen 3.3% Component of protein and nucleic acid.
Calcium 1.5% Component of bone, teeth, trigger for muscle contraction and enzyme
activator.
Phosphorus 1.0% Backbone of nucleic acid and energy transfer.
Potassium 0.4% Important in nerve function and stomatal movement.
Sulphur 0.3% Component of most proteins.
Chlorine 0.2% Principal negative ion in the cells.
Sodium 0.2% Principal positive ion bathing cell and important in nerve function.
Magnesium 0.1% Component of many energy transferring enzyme and chlorophyll.
Iron Trace Critical component of haemoglobin and important in chlorophyll synthesis.
Metabolites
These are those biomolecules which are either utilised in metabolic functions or
synthesised by the cellular machinery. These are of two types
1. The primary metabolites in an animal tissue are sugars, amino acids, fatty acids,
fats and oils, nucleosides and nucleotides.
2. In plants, fungal and microbial cells, there are thousands of compounds other than
primary metabolites, e.g. alkaloides, flavonoides, rubber, essential oils, antibiotics,
, coloured pigments, scents, gums, spices. These are called
secondary metabolites.
Types of Carbohydrates
The carbohydrates can be divided into three major groups on
Some Secondary Metabolites the basis of hydrolysis products as follows
Group Metabolite
Types of Carbohydrates
Pigments Carotenoids, anthocyanins, etc.
Occurrence
Alkaloids Morphine, codeine, etc. CHO Type Compound Sub-unit in Living
Terpenoides Monoterpenes, diterpenes, etc. Thing
Monosaccharide Glucose — Widespread
Essential oils Lemon grasss oil, etc.
Fructose — Sweet fruits
Toxins Abrin and ricin.
Galactose — Milk
Lectins Concanavalin A. Oligosaccharide Maltose 2 × Glucose Germinating
Drugs Vinblastin, curcumin, etc. seeds
Sucrose Glucose + Fructose Sugarcane
Polymeric substances Rubber, gums and cellulose.
Lactose Glucose + Galactose Milk
l
Secondary metabolites are organic compounds that are Raffinose Glucose + Fructose Plants
not directly involved in the normal growth and + Galactose
development or reproduction of an organism. Polysaccharide Starch Glucose Plants
(storage)
l
These are often restricted to a narrow set of species
Glycogen Glucose Animals
within a phylogenetic group.
(storage)
l
Secondary metabolites often play an important role in Cellulose Glucose Plant cell
plant defence against herbivory and other interspecies walls
defences. Chitin Glucosamine Arthropod
exoskeletons
Biomolecules (i) Monosaccharides
These chemical compounds found in living organisms are of l
These are the simplest group of carbohydrate and cannot
two types be hydrolysed further to give simpler units of
polyhydroxyaldehyde or ketone.
(i) Microbiomolecules The molecules, which have
molecular weights less than one thousand dalton are l
They are referred as simple sugars. They are sweet in tast,
usually referred to as micromolecules or simply colourless solids having solubility in water, but sparingly
biomolecules. soluble in alcohol and insoluble in ether.
(ii) Macrobiomolecules The molecules which are found in l
These have atleast one asymmetric carbon atom, hence
the acid insoluble fraction are called biomacromolecules. they exist in different isomeric forms.
The chemical composition of living tissue from l
The term ‘reducing’ reflects the fact that some sugars have
abundance point of view is given below carbonyl groups (C == O), which can be oxidised to
carboxylic acids ( COOH), reducing other chemicals in
Average Composition of Cells the process.
Component Percentage of the Total Cellular Mass l
A standard test for a reducing sugar is Benedict’s solution,
Water 70-90 a blue solution that contains copper sulphate. If a
Proteins 10-15 reducing sugar is present, the Cu (I) ions result in an
orange precipitate.
Carbohydrates 3
l
Glucose, fructose, galactose, maltose and lactose are all
Lipids 2
reducing sugars but sucrose is a non-reducing sugar.
Nucleic acids 5-7 However, after sucrose is boiled with dilute acid to
Ions 1 hydrolyse it into its monosaccharides, it produces a
positive result.
O–
Carbohydrates H
—
—
C==O
C==O
—
They are the basic component of food and principal source of
+2Cu2+ + 5OH–
—
energy, which are composed of carbon (C), hydrogen (H) and H—C—OH + 2Cu
H—C—OH
—
+
—
oxygen (O) in the approximate ratio of 1 : 2 : 1. CH2OH 3H O
CH2OH 2
, D-Glyceraldehyde is a three carbon, aldotriose (aldose sugar + (b) Maltose or Malt sugar It is not common in nature
triose sugar). It is also the smallest carbohydrate. except in germinating starchy seeds.
l
D-Ribose is an important sugar used in genetic material. This It is referred to as β–maltose because the unreacted
sugar is not used as an energy source but is a part of the C-1 on β-D glucose is in the β position.
backbone of RNA. CH2OH CH2OH
l
When OH group of C-2 position is removed (H in place of O O
H H H OH
OH) from ribose, the sugar becomes deoxyribose, which is
H H
used in the backbone of DNA. OH H O OH H
HO H
l
Pentose sugar ribose is found in every animal cell. It is the
main constituent of ATP, ADP, riboflavin and RNA. H OH H OH
α-D-glucose β-D-glucose
(ii) Oligosaccharides Maltose, α (1-4) linkage
l
These are the group of compounds, which on hydrolysis
produce two or more molecules of same or different
l
Maltose is produced commercially from starch by a
monosaccharide unit held together by a glycosidic bond. starch hydrolysing enzyme diastase.
l
They are crystalline, water soluble and sweet to taste. They (c) Lactose or Milk sugar It is a dimer of β-D galactose
can be disaccharide, trisaccharide, tetrasaccharide and so on. and either the α or β-D glucose.
l
The carbon that carries the aldehyde or the ketone can react CH2OH CH2OH
with any hydroxyl group on a second sugar molecule to form O O
a bond called glycosidic bond. HO H OH
β-Lactose H H
l
Based on the position of the C − 1 OH, glycosidic bonds may H O OH
OH H
be H H
H
(a) α- glycosidic bond linkage between a C − 1 α OH and a
H OH H OH
C − 4 OH. β-galactose β-D-glucose
(b) β − glycosidic bond linkage between a C-1 β OH and a Lactose, β-(1-4) linkage, β-disaccharide
C-4OH.
l
Lactose does not occur in nature except as a
α-bonds β-bonds
product of the mammary gland. Compared to milk
O O O O of cow, buffalo and goat, lactose quantity is highest
in the human milk.
l
C-4 end can be either up or down depending on the
orientation of the monosaccharide.
(iii) Polysaccharides
l
Cellobiose consists of two molecules of β-D glucose.
l
These are long chains of sugars. They are threads
containing different monosaccharide units as building
l
It is similar to maltose except in the presence of β (1 − 4)
blocks.
linkage in cellobiose instead of α(1-4) in maltose.
l
For example, cellulose is a polymeric polysaccharide
l
Due to the presence of β (1-4) linkage, cellobiose is
consisting of only one type of monosaccharide, i.e.
undigestible.
glucose.
Examples of oligosaccharides are as follows l
The major polysaccharides of interest in nutrition are
(a) Sucrose or Table sugar It is found in sugarcane and glycogen, found in certain animal tissues and starch and
sugarbeet up to 20 % by mass. cellulose, both of plant origin.
CH2OH l
All these polysaccharides consist of only glucose units.
H
O l
They may be either homopolysaccharides (i.e.
H
H containing a single type of monomers, e.g. starch,
Glucose
unit OH H glycogen, cellulose, chitin) or heteropolysaccharides (i.e.
HO containing two or more different units), e.g.
O α (1-2) hemicellulose, pectic substances, some gums, etc.
H OH Glycosidic
CH2OHO linkage Some of the complex carbohydrates present in nature are as
Fructose follows
unit H HO 1. Glucans are polymers of glucose monomers,
H
CH2OH e.g. starch, glycogen, cellulose, chitin.
OH H 2. Galactans are polymers of galactose monomers,
Sucrose e.g. agar-agar, pectin, galacton from snails.
Biomolecules
and Enzymes
Learning & Revision for the Day
u Metabolites u Proteins u Nucleic Acids
u Biomolecules u Lipids u Enzymes
u Carbohydrates
Chemicals or molecules present in the living organisms are essential for the maintenance
of their physiological processes. These are known as biomolecules. These include large
molecules like proteins, nucleic acids, polysaccharides, lipids and small molecules like
metabolites.
Mineral Elements and Their Functions in the Body
Element Percentage Function
Oxygen 65% Cellular respiration and component of water.
Carbon 18% Backbone of organic molecules.
Hydrogen 9.5% Electron carrier, component of water and most organic molecules.
Nitrogen 3.3% Component of protein and nucleic acid.
Calcium 1.5% Component of bone, teeth, trigger for muscle contraction and enzyme
activator.
Phosphorus 1.0% Backbone of nucleic acid and energy transfer.
Potassium 0.4% Important in nerve function and stomatal movement.
Sulphur 0.3% Component of most proteins.
Chlorine 0.2% Principal negative ion in the cells.
Sodium 0.2% Principal positive ion bathing cell and important in nerve function.
Magnesium 0.1% Component of many energy transferring enzyme and chlorophyll.
Iron Trace Critical component of haemoglobin and important in chlorophyll synthesis.
Metabolites
These are those biomolecules which are either utilised in metabolic functions or
synthesised by the cellular machinery. These are of two types
1. The primary metabolites in an animal tissue are sugars, amino acids, fatty acids,
fats and oils, nucleosides and nucleotides.
2. In plants, fungal and microbial cells, there are thousands of compounds other than
primary metabolites, e.g. alkaloides, flavonoides, rubber, essential oils, antibiotics,
, coloured pigments, scents, gums, spices. These are called
secondary metabolites.
Types of Carbohydrates
The carbohydrates can be divided into three major groups on
Some Secondary Metabolites the basis of hydrolysis products as follows
Group Metabolite
Types of Carbohydrates
Pigments Carotenoids, anthocyanins, etc.
Occurrence
Alkaloids Morphine, codeine, etc. CHO Type Compound Sub-unit in Living
Terpenoides Monoterpenes, diterpenes, etc. Thing
Monosaccharide Glucose — Widespread
Essential oils Lemon grasss oil, etc.
Fructose — Sweet fruits
Toxins Abrin and ricin.
Galactose — Milk
Lectins Concanavalin A. Oligosaccharide Maltose 2 × Glucose Germinating
Drugs Vinblastin, curcumin, etc. seeds
Sucrose Glucose + Fructose Sugarcane
Polymeric substances Rubber, gums and cellulose.
Lactose Glucose + Galactose Milk
l
Secondary metabolites are organic compounds that are Raffinose Glucose + Fructose Plants
not directly involved in the normal growth and + Galactose
development or reproduction of an organism. Polysaccharide Starch Glucose Plants
(storage)
l
These are often restricted to a narrow set of species
Glycogen Glucose Animals
within a phylogenetic group.
(storage)
l
Secondary metabolites often play an important role in Cellulose Glucose Plant cell
plant defence against herbivory and other interspecies walls
defences. Chitin Glucosamine Arthropod
exoskeletons
Biomolecules (i) Monosaccharides
These chemical compounds found in living organisms are of l
These are the simplest group of carbohydrate and cannot
two types be hydrolysed further to give simpler units of
polyhydroxyaldehyde or ketone.
(i) Microbiomolecules The molecules, which have
molecular weights less than one thousand dalton are l
They are referred as simple sugars. They are sweet in tast,
usually referred to as micromolecules or simply colourless solids having solubility in water, but sparingly
biomolecules. soluble in alcohol and insoluble in ether.
(ii) Macrobiomolecules The molecules which are found in l
These have atleast one asymmetric carbon atom, hence
the acid insoluble fraction are called biomacromolecules. they exist in different isomeric forms.
The chemical composition of living tissue from l
The term ‘reducing’ reflects the fact that some sugars have
abundance point of view is given below carbonyl groups (C == O), which can be oxidised to
carboxylic acids ( COOH), reducing other chemicals in
Average Composition of Cells the process.
Component Percentage of the Total Cellular Mass l
A standard test for a reducing sugar is Benedict’s solution,
Water 70-90 a blue solution that contains copper sulphate. If a
Proteins 10-15 reducing sugar is present, the Cu (I) ions result in an
orange precipitate.
Carbohydrates 3
l
Glucose, fructose, galactose, maltose and lactose are all
Lipids 2
reducing sugars but sucrose is a non-reducing sugar.
Nucleic acids 5-7 However, after sucrose is boiled with dilute acid to
Ions 1 hydrolyse it into its monosaccharides, it produces a
positive result.
O–
Carbohydrates H
—
—
C==O
C==O
—
They are the basic component of food and principal source of
+2Cu2+ + 5OH–
—
energy, which are composed of carbon (C), hydrogen (H) and H—C—OH + 2Cu
H—C—OH
—
+
—
oxygen (O) in the approximate ratio of 1 : 2 : 1. CH2OH 3H O
CH2OH 2
, D-Glyceraldehyde is a three carbon, aldotriose (aldose sugar + (b) Maltose or Malt sugar It is not common in nature
triose sugar). It is also the smallest carbohydrate. except in germinating starchy seeds.
l
D-Ribose is an important sugar used in genetic material. This It is referred to as β–maltose because the unreacted
sugar is not used as an energy source but is a part of the C-1 on β-D glucose is in the β position.
backbone of RNA. CH2OH CH2OH
l
When OH group of C-2 position is removed (H in place of O O
H H H OH
OH) from ribose, the sugar becomes deoxyribose, which is
H H
used in the backbone of DNA. OH H O OH H
HO H
l
Pentose sugar ribose is found in every animal cell. It is the
main constituent of ATP, ADP, riboflavin and RNA. H OH H OH
α-D-glucose β-D-glucose
(ii) Oligosaccharides Maltose, α (1-4) linkage
l
These are the group of compounds, which on hydrolysis
produce two or more molecules of same or different
l
Maltose is produced commercially from starch by a
monosaccharide unit held together by a glycosidic bond. starch hydrolysing enzyme diastase.
l
They are crystalline, water soluble and sweet to taste. They (c) Lactose or Milk sugar It is a dimer of β-D galactose
can be disaccharide, trisaccharide, tetrasaccharide and so on. and either the α or β-D glucose.
l
The carbon that carries the aldehyde or the ketone can react CH2OH CH2OH
with any hydroxyl group on a second sugar molecule to form O O
a bond called glycosidic bond. HO H OH
β-Lactose H H
l
Based on the position of the C − 1 OH, glycosidic bonds may H O OH
OH H
be H H
H
(a) α- glycosidic bond linkage between a C − 1 α OH and a
H OH H OH
C − 4 OH. β-galactose β-D-glucose
(b) β − glycosidic bond linkage between a C-1 β OH and a Lactose, β-(1-4) linkage, β-disaccharide
C-4OH.
l
Lactose does not occur in nature except as a
α-bonds β-bonds
product of the mammary gland. Compared to milk
O O O O of cow, buffalo and goat, lactose quantity is highest
in the human milk.
l
C-4 end can be either up or down depending on the
orientation of the monosaccharide.
(iii) Polysaccharides
l
Cellobiose consists of two molecules of β-D glucose.
l
These are long chains of sugars. They are threads
containing different monosaccharide units as building
l
It is similar to maltose except in the presence of β (1 − 4)
blocks.
linkage in cellobiose instead of α(1-4) in maltose.
l
For example, cellulose is a polymeric polysaccharide
l
Due to the presence of β (1-4) linkage, cellobiose is
consisting of only one type of monosaccharide, i.e.
undigestible.
glucose.
Examples of oligosaccharides are as follows l
The major polysaccharides of interest in nutrition are
(a) Sucrose or Table sugar It is found in sugarcane and glycogen, found in certain animal tissues and starch and
sugarbeet up to 20 % by mass. cellulose, both of plant origin.
CH2OH l
All these polysaccharides consist of only glucose units.
H
O l
They may be either homopolysaccharides (i.e.
H
H containing a single type of monomers, e.g. starch,
Glucose
unit OH H glycogen, cellulose, chitin) or heteropolysaccharides (i.e.
HO containing two or more different units), e.g.
O α (1-2) hemicellulose, pectic substances, some gums, etc.
H OH Glycosidic
CH2OHO linkage Some of the complex carbohydrates present in nature are as
Fructose follows
unit H HO 1. Glucans are polymers of glucose monomers,
H
CH2OH e.g. starch, glycogen, cellulose, chitin.
OH H 2. Galactans are polymers of galactose monomers,
Sucrose e.g. agar-agar, pectin, galacton from snails.
