DNA codon table

The genetic code is traditionally represented as an RNA codon table because, when proteins are made in a cell by ribosomes, it is mRNA that directs protein synthesis. The mRNA sequence is determined by the sequence of genomic DNA. With the rise of computational biology and genomics, most genes are now discovered at the DNA level, so a DNA codon table is becoming increasingly useful. The DNA codons in such tables occur on the sense DNA strand and are arranged in a 5' → 3' direction.

^A The codon ATG both codes for methionine and serves as an initiation site: the first ATG in an mRNA's coding region is where translation into protein begins. ^{B ^ ^ ^} The historical basis for designating the stop codons as amber, ochre and opal is described in an autobiography by Sydney Brenner and in a historical article by Bob Edgar.