Amino acids are organic compounds containing amine (−NH2) and carboxyl (-COOH) functional groups. There are basically four different classes of amino acids determined by different side chains: (1) non-polar and neutral, (2) polar and neutral, (3) acidic and polar, (4) basic and polar. Eight amino acids are essential for humans, as the body cannot produce them by themselves, and they have to be supplied externally. These are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Amino acids are the building blocks of it. A large proportion of our cells, muscles and tissue is made up of amino acids, meaning they carry out many important bodily functions, such as giving cells their structure.