Genes [1] vary in size from about 3 000 - 50 000 base pairs (3-50 kbp),
depending on the particular gene and the organism.
Genes [2] code for the production of proteins which are composed of
sub-units called amino acids. [3] Structural, functional and regulatory
proteins determine the characteristics of the organism. For example:
* proteins form hormones, e.g. insulin, antibodies, the keratin of hair
and claws;
* proteins are involved in transport e.g. haemoglobin which transports
O2;
* enzymes (proteins) control chemical reactions;
* contractile proteins (actin, Miocene) in cells enable muscular
activity.
