A group of three nucleotides is called a codon that codes for a specific amino acid in the protein. There are 20 essential amino acids present in human body and are required in the diet.
Each amino acid is given a one-letter code that makes the study of amino acid sequences easy. One letter code for the given amino acid sequence Glutamic Acid-Histidine-Tyrosine is E-H-Y in which E is code for Glutamic Acid, H is a code for Histidine, and Y is a code for Tyrosine.