The codon table (standard genetic code) maps each of the 64 three-base codons to an amino acid or a stop signal. Use the lookup to go from a codon to its amino acid — or from an amino acid to all the codons that encode it — and the full table below as a reference.
Standard genetic code (NCBI translation table 1). ATG (Met) is the usual start; TAA, TAG and TGA are stop codons. To translate a whole sequence, use the DNA→protein tool.
How to read the genetic code
mRNA is read in non-overlapping triplets (codons), 5’→3′, starting at the start codon. Each codon specifies one amino acid:
- Start:
ATG(AUG in RNA) codes for methionine and usually begins translation. - Stop:
TAA,TAGandTGAend translation and encode no amino acid. - Degeneracy: the code is redundant — most amino acids are specified by several codons (leucine, serine and arginine each have six), which is why silent mutations exist.
Reading frames
A sequence can be read in three frames per strand. The right frame is the one that begins at the start codon and runs to a stop without interruption. To translate a whole sequence in any frame, use the DNA→protein translator.
Frequently asked questions
What is the start codon?
ATG (AUG), which codes for methionine and marks the usual start of translation.
What are the three stop codons?
TAA, TAG and TGA — they terminate translation and encode no amino acid.
Why do several codons code for the same amino acid?
The genetic code is degenerate (redundant): 61 sense codons encode 20 amino acids, so most amino acids have more than one codon. This buffers many point mutations.
Is this the same code in all organisms?
The standard code (table 1) applies to nuclear genes in most organisms; a few use variant codes (e.g. mitochondria), which this table does not show.
Related tool: DNA to protein translator →
