Page 11 - Lesson Notes - Biomolecules 1

Hence, on the basis of the number and types of monomer present, polymers are of
following two types
(i) Homopolymers, are those which have only one type of monomer present. These
monomer can be repeated n number of times in a chain, e.g., Starch, insulin, etc.
(ii) Heteropolymers, are those which have two or more than two types of monomers,
e.g., Proteins.Various macromolecules and their major roles are described under as
Lipids
The molecules in the insoluble fraction are polymeric substances except lipids.
Athough lipids have their molecular weight not exceeding above 800 Da, but still it
comes under acid insoluble fraction, i.e., biomacromolecular category.
This happens because these are small moleculer weight compounds and are present
not only as such, but also arranged in structures like cell membranes and other
membranes.
Thus, when we grind a tissue, we disrupt the cell structure, cell membrane and other
membranes are broken down into pieces and form vesicles that are not water
soluble. Therefore, these are separated along with acid insoluble pool and are placed
in macromolecules.
Lipids are not strictly biomacromolecule.
If representation of the chemical- composition of living tissue is done from
abundance point of view and arranged class-wise, it is observed that water is the
most abundant chemical in living organisms.
Average Composition of Cells
i. Primary Structure
It is the description of basic structure of a protein. This includes number and
sequence of amino acids in each polypeptide. The distance between two adjacent
peptide bonds is about 0.35 nm.
A protein is imagined as a line whose left end is represented by the first amino acid,
also called as the N-terminal amino acid and the right end is represented by the last
amino acid called the C-terminal amino add, e.g., Insulin, ribonudease.

Proteins
These are the most important and abundant intracellular organic biomoLecules.
These are polypeptides having chains of amino acid arranged linearly that are linked
by peptide bonds.
Thus, each protein is a polymer of amino acids (as studied earlier in the chapter),
there are 20 types of amino acids, e.g., Alanine, valine arginine, leucine, histidine, etc.
So, proteins are considered as heteropolymer.
These amino acids are divided into two main types, on the basis of their utility
(i) Essential Amino Adds These are those amino acids that are essential for our