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Codon

A codon is a triplet of DNA or RNA nucleotides. In a Protein Encoding Gene, a codon specifies a single amino acid (see Amino Acid Codes) or a stop codon that marks the end of the gene.

Below is the section of DNA near fig|100226.1.peg.30, a hypothetical protein from Streptomyces coelicolor A3(2) primarily chosen because it's short (though not quite short enough to fit on a normal screen). This particular section begins and ends with a stop codon, so it is known as an open reading frame: that is, a section of DNA that could contain a gene. The actual hypothetical protein begins with the GTG start marker, which translates into Methionine, the standard amino acid for starting a protein. The final protein will be MLMSHGGEVEEGACQCSFI (the stop codon doesn't translate).

tga ccg gag gag gca acc tca ccg cta cgt gtc ctg cgg gcg gcg cag ccg cgg tgg ccg cgg ggc ccc GTG CTC ATG AGC CAC GGC GGG GAG GTC GAG GAG GGG GCT TGT CAG TGC TCG TTC ATA tga
 *   P   E   E   A   T   S   P   L   R   V   L   R   A   A   Q   P   R   W   P   R   G   P   M   L   M   S   H   G   G   E   V   E   E   G   A   C   Q   C   S   F   I   *

You can use the form below to translate DNA codons to protein strings. Type (or paste) the DNA into the text box, using only the standard DNA letters a, c, g, and t, then click the TRANSLATE button to see the resulting protein string.

Further reading:

• Amino Acid Codes
• Messenger RNA
• Transfer RNA