UNIT 3 CELL: STRUCTURE AND FUNCTIONS

Chapter 8
Cell: The Unit of Life

Chapter 9
Biomolecules

Chapter 10
Cell Cycle and
Cell Division

Biology is the study of living organisms. The detailed description of
their form and appearance only brought out their diversity. It is the
cell theory that emphasised the unity underlying this diversity of forms,
i.e., the cellular organisation of all life forms. A description of cell
structure and cell growth by division is given in the chapters comprising
this unit. Cell theory also created a sense of mystery around living
phenomena, i.e., physiological and behavioural processes. This mystery
was the requirement of integrity of cellular organisation for living
phenomena to be demonstrated or observed. In studying and
understanding the physiological and behavioural processes, one can
take a physico-chemical approach and use cell-free systems to
investigate. This approach enables us to describe the various processes
in molecular terms. The approach is established by analysis of living
tissues for elements and compounds. It will tell us what types of organic
compounds are present in living organisms. In the next stage, one can
ask the question: What are these compounds doing inside a cell? And,
in what way they carry out gross physiological processes like digestion,
excretion, memory, defense, recognition, etc. In other words we answer
the question, what is the molecular basis of all physiological processes?
It can also explain the abnormal processes that occur during any
diseased condition. This physico-chemical approach to study and
understand living organisms is called ‘Reductionist Biology’. The
concepts and techniques of physics and chemistry are applied to
understand biology. In Chapter 9 of this unit, a brief description of
biomolecules is provided.

G.N. RAMACHANDRAN, an outstanding figure in the field of protein
structure, was the founder of the ‘Madras school’ of
conformational analysis of biopolymers. His discovery of the triple
helical structure of collagen published in Nature in 1954 and his
analysis of the allowed conformations of proteins through the
use of the ‘Ramachandran plot’ rank among the most outstanding
contributions in structural biology. He was born on October 8,
1922, in a small town, not far from Cochin on the southwestern
coast of India. His father was a professor of mathematics at a
local college and thus had considerable influence in shaping
Ramachandran’s interest in mathematics. After completing his
school years, Ramachandran graduated in 1942 as the top-
ranking student in the B.Sc. (Honors) Physics course of the
University of Madras. He received a Ph.D. from Cambridge
University in 1949. While at Cambridge, Ramachandran met
Linus Pauling and was deeply influenced by his publications on
models of the α-helix and β-sheet structures that directed his
attention to solving the structure of collagen. He passed away at the age of 78, on April 7, 2001.

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