- Each genetic code consists of three neighbouring nucleotides.
>Such a set of three nucleotides is known as a codon.
- Each codon specifies either one of the 20 amino acids that are used in protein synthesis or it gives a signal to start protein synthesis or a stop signal for the termination of protein synthesis.
- The sequence of codons in the messenger RNA (mRNA) molecule thus determines the sequence of amino acids in the protein.
- The genetic code is degenerate i.e., more than one codon may specify the same amino acid.
- Out of the 64 possible codons, 61 code for amino acids and the remaining three codons are termination or stop codons which do not code for any amino acid.
- The codon AUG has dual functions. It codes for the amino acid methionine and it also functions as the initiation codon or the start codon i.e., it signals the beginning of a polypeptide chain.
