: Amino acids are groups of subunits that are polymerized to form proteins. There are 20 aminoacids commonly and universally found in proteins. Amino acids may be essential and non essential. Essential amino acids can not be synthesized by higher vertebrates hence, must be included in the diet. Eg- isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Non essential amino acids can be synthesized by the organisms and may not be the required component of diet. Eg. tyrosine, serine aspartic acid, glutamic acid, proline, alanine etc.