Codon is a set of three nucleotides(triplets) in mRNA, functioning as a unit of genetic coding by specifying a particular amino acid during the synthesis of polypeptides/proteins in a cell. The genetic code comprises of 64 such triplets of nucleotides which code for twenty amino acids.

A codon specifies a transfer RNA carrying a specific amino acid, which is incorporated into a polypeptide chain during protein synthesis. The specificity for translating genetic information from DNA into mRNA, then to protein, is provided by codon-anticodon pairing.

Sixty-one codons encode the 20 amino acids, leading to codon redundancy, and three codons signal termination of polypeptide synthesis.The initiating codon is AUG/ATG which codes for methionine. UAA/TAA, UGA/TGA, UAG/TAG are the terminating codons.

Properties of Genetic Code