Amino Acids

The chemical subunits of polypeptides and proteins, and therefore one of the fundamental building blocks of life as we know it. An amino acid consists of a central carbon atom attached to a carboxyl group (–COOH), an amino group (–NH₂), a hydrogen atom, and a side group (–R), giving the general formula R-CH-NH₂-COOH. Only the side group differs from one amino acid to another; R may be a hydrogen or an organic group and determines the properties of a particular amino acid.



Amino acids link togehter through a special bond, called a peptide bond, to form peptides, which are short chains, or polypeptides, which are much longer chains. Proteins are made up of various proportions of 20 commonly occuring amino acids (see the table below). The sequence of these amino acids in the protein determines the protein's molecular shape, properties, and biolgical role.

Plants and many microorganisms can synthesize amino acids from simple inorganic compounds, but animals must obtain the amino acids they need in their diet. So-called sssential amino acids are those that an organism, such as a human being, must obtain ready-made from its environment.

http://www.daviddarling.info/encyclopedia/A/amino.html

http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/proteins.htm
http://nobelprize.org/educational/medicine/dna/a/translation/aminoacids.html