Kwayoyin sunadarai ne mai sa na uku-nucleotide sets kira codons da kowane uku-nucleotide hade designates wani amino acid, misali AUG (adenine-uracil-guanine) shi ne code for methionine. Saboda DNA ƙunshi hudu nucleotides, jimlar adadin yiwu codons ne 64; Saboda haka, akwai wasu redundancy a cikin kwayoyin halitta code, tare da wasu amino acid kayyade da fiye da daya codon. Genes coded a cikin DNA ne na farko transcribed cikin pre-mRNA (mRNA) da bayanai encoded a cikin kwayoyin halitta kamar RNA.
Adenine-uracil-guanine