A living system grows, sustains and reproduces itself.
The most amazing thing about a living system is that it
is composed of non-living atoms and molecules. The
pursuit of knowledge of what goes on chemically within
a living system falls in the domain of biochemistry. Living
systems are made up of various complex biomolecules
like carbohydrates, proteins, nucleic 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. In
addition, some simple molecules like vitamins and
mineral salts also play an important role in the functions
of organisms. Structures and functions of some of these
biomolecules are discussed in this Unit.
BiomoleculesBiomolecules
BiomoleculesBiomolecules
Biomolecules
BiomoleculesBiomolecules
BiomoleculesBiomolecules
Biomolecules
After studying this Unit, you will be
able to
• explain the characteristics of
biomolecules like carbohydrates,
proteins and nucleic acids and
hormones;
• classify carbohydrates, proteins,
nucleic acids and vitamins on the
basis of their structures;
• explain the difference between
DNA and RNA;
• describe the role of biomolecules
in biosystem.
Objectives
“It is the harmonious and synchronous progress of chemical
reactions in body which leads to life”.
14
Unit
Unit
Unit
Unit
Unit
14
Carbohydrates are primarily produced by plants and form a very large
group of naturally occurring organic compounds. Some common
examples of carbohydrates are cane sugar, glucose, starch, etc. Most of
them have a general formula, C
x
(H
2
O)
y
, and were considered as hydrates
of carbon from where the name carbohydrate was derived. For example,
the molecular formula of glucose (C
6
H
12
O
6
) fits into this general formula,
C
6
(H
2
O)
6
. But all the compounds which fit into this formula may not be
classified as carbohydrates. For example acetic acid (CH
3
COOH) fits into
this general formula, C
2
(H
2
O)
2
but is not a carbohydrate. Similarly,
rhamnose, C
6
H
12
O
5
is a carbohydrate but does not fit in this definition.
A large number of their reactions have shown that they contain specific
functional groups. Chemically, the carbohydrates may be defined as
optically active polyhydroxy aldehydes or ketones or the compounds
which produce such units on hydrolysis. Some of the carbohydrates,
which are sweet in taste, are also called sugars. The most common
sugar, used in our homes is named as sucrose whereas the sugar present
14.114.1
14.114.1
14.1
CarbohydratesCarbohydrates
CarbohydratesCarbohydrates
Carbohydrates