Although amino acids may have other formulas, those in protein invariably have the general formula RCH(NH2)COOH, where C is carbon, H is hydrogen, N is nitrogen, O is oxygen, and R is a group, varying in composition and structure, called a side chain.Proteins are the most functional molecules found in living organisms, and they play vital roles in their survival. Proteins are the macronutrient that helps to build muscles of our body. They have primary, secondary, tertiary, and quaternary structures of protein. The ability of the polypeptide chain to fold into complex three-dimensional configurations that allow it to bind multiple molecules and perform various functions accounts for the wide range of functions it can perform.