Ch 9Biomolecules — Class 11 Biology, concept-first.

Every living cell is a highly organised chemical system, built from a mixture of very small molecules and very large ones.

Amino acids are the monomeric building blocks from which every protein is constructed. Each of the twenty standard amino acids found in proteins shares a common general structure: a central carbon ato…

A functional protein is not simply a random tangle of amino acids but a precisely folded molecule whose three-dimensional shape is described at four distinct, hierarchical levels of organisation.

Beyond the four structural levels examined in the previous section, proteins are also classified in two complementary ways -- by their overall molecular shape and by the biological function they perfo…

Carbohydrates are polyhydroxy aldehydes or ketones, broadly following the general formula (CH2O)n, and serve chiefly as the immediate and stored source of chemical energy for the cell, in addition to…

Lipids are a chemically diverse group of biomolecules united chiefly by their common physical property of being insoluble in water but soluble in non-polar organic solvents such as ether, chloroform a…

Nucleic acids are the biomacromolecules responsible for storing, transmitting and expressing genetic information in every living cell, and are themselves polymers built from repeating monomer units ca…

Enzymes are biological catalysts -- substances that speed up the rate of a specific biochemical reaction without themselves being permanently altered or consumed in the process -- and, with the notabl…

An enzyme's ability to recognise and act on one particular substrate, out of the thousands of molecules present in a cell, depends on its active site -- a specific, often cleft-like or pocket-like reg…

The rate at which an enzyme catalyses its reaction is not constant but is sensitive to several physical and chemical conditions, each of which a student of enzymology needs to understand individually.

This chapter surveyed the chemical constituents of living cells, beginning with the distinction between the small, acid-soluble micromolecules -- amino acids, monosaccharides, nucleotides and lipids -…