Proteins are built of numerous smaller entity known as amino acids. There are 500 different amino acids but only 20 amino acids compose the proteins present in a human body. There are 20 various type of amino acids that can be incorporated to produce a protein. Each of these 20 amino acid is specific chemically and has the ability to develop in any arrangement in a chain of protein. Because of this arrangements in innumerable varied sequence, the capacity to produce 400,000 proteins out of 20 various amino acids is a possibililty.