DNA encodes protein sequence by a series of three-nucleotide codons. Sets of three nucleotides, known as codons, each correspond to a specific amino acid. There are three amino acids encoded by six different codons&colon; serine, leucine, and arginine. The genetic code specifies the correspondence during protein translation between codons and amino acids. In the genetic code, there are 4 = 64 possible codons (tri-nucleotide sequences). These new codons can code for new amino acids. The correspondence between codons and amino acids is nearly universal among all known living organisms. Pyrrolysine and selenocysteine are encoded via variant codons. It is encoded by the codons GAU and GAC. It is encoded by the codons CAA and CAG. It is encoded by the codons UUU and UUC. It is encoded by the codons GAA or GAG. It is encoded by the codons AAA and AAG. It is encoded by the codons AAU and AAC. It is encoded by the codons AUU, AUC, and AUA.