Proteins present very diverse structures and activities. They play crucial roles in almost all biological processes.
For example enzymes are proteins,
which speed up transformations or reactions by a million fold.
Proteins also play an important role in immune protection as antibodies are
highly specific proteins that distinguish between the body and foreign substances
such as bacteria.
Amino acids are the basic structural units of proteins. There are about twenty different amino acids that are easily linked to form linear chains. These chains fold up to form complex three dimensional structures.
The sequence of amino
acids in a protein is linked to the information contained in the nucleus. Without
going into complex details, imagine that each gene in the chromosome corresponds
to a certain sequence of amino acids.
An enzyme complex 'reads' the genes and synthesises the protein accordingly.
It is very important to realise that the function of a protein depend of the sequence of amino acids, which can be altered by changing the genes.