Amino Acids are the building blocks of all life. Although over 500 exist in nature, the human genetic code "codes for" (carries the intructions for) only 20. 




The generalised structure of an amino acid is as shown in the diagram above. On the left we have the standard amino or amine group, NH2 and on the right the standard carboxylic acid functional group COOH. The chiral carbon atom in the middle contains a single hydrogen atom and a functional group which we have denoted as R in this case. The variation in the functional group R is what distinguishes between all of the different amino acids.