Codon Table
The standard genetic code — 64 codons mapped to amino acids.
64 codons
| Codon | AA (1-letter) | AA (3-letter) | Full name |
|---|---|---|---|
| TTT | F | Phe | Phenylalanine |
| TTC | F | Phe | Phenylalanine |
| TTA | L | Leu | Leucine |
| TTG | L | Leu | Leucine |
| CTT | L | Leu | Leucine |
| CTC | L | Leu | Leucine |
| CTA | L | Leu | Leucine |
| CTG | L | Leu | Leucine |
| ATT | I | Ile | Isoleucine |
| ATC | I | Ile | Isoleucine |
| ATA | I | Ile | Isoleucine |
| ATG Start | M | Met | Methionine |
| GTT | V | Val | Valine |
| GTC | V | Val | Valine |
| GTA | V | Val | Valine |
| GTG | V | Val | Valine |
| TCT | S | Ser | Serine |
| TCC | S | Ser | Serine |
| TCA | S | Ser | Serine |
| TCG | S | Ser | Serine |
| CCT | P | Pro | Proline |
| CCC | P | Pro | Proline |
| CCA | P | Pro | Proline |
| CCG | P | Pro | Proline |
| ACT | T | Thr | Threonine |
| ACC | T | Thr | Threonine |
| ACA | T | Thr | Threonine |
| ACG | T | Thr | Threonine |
| GCT | A | Ala | Alanine |
| GCC | A | Ala | Alanine |
| GCA | A | Ala | Alanine |
| GCG | A | Ala | Alanine |
| TAT | Y | Tyr | Tyrosine |
| TAC | Y | Tyr | Tyrosine |
| TAA | * | Stop | Stop |
| TAG | * | Stop | Stop |
| CAT | H | His | Histidine |
| CAC | H | His | Histidine |
| CAA | Q | Gln | Glutamine |
| CAG | Q | Gln | Glutamine |
| AAT | N | Asn | Asparagine |
| AAC | N | Asn | Asparagine |
| AAA | K | Lys | Lysine |
| AAG | K | Lys | Lysine |
| GAT | D | Asp | Aspartic acid |
| GAC | D | Asp | Aspartic acid |
| GAA | E | Glu | Glutamic acid |
| GAG | E | Glu | Glutamic acid |
| TGT | C | Cys | Cysteine |
| TGC | C | Cys | Cysteine |
| TGA | * | Stop | Stop |
| TGG | W | Trp | Tryptophan |
| CGT | R | Arg | Arginine |
| CGC | R | Arg | Arginine |
| CGA | R | Arg | Arginine |
| CGG | R | Arg | Arginine |
| AGT | S | Ser | Serine |
| AGC | S | Ser | Serine |
| AGA | R | Arg | Arginine |
| AGG | R | Arg | Arginine |
| GGT | G | Gly | Glycine |
| GGC | G | Gly | Glycine |
| GGA | G | Gly | Glycine |
| GGG | G | Gly | Glycine |
Learn more
What it does
The codon table tool displays the standard genetic code, mapping all 64 codons to their amino acids, start and stop signals. Students, teachers and bench scientists use it for quick lookups during cloning, mutagenesis and sequence interpretation. The standard code is shared by nearly all organisms, which is why a bacterial expression system can translate a human gene — though exceptions exist in mitochondria and a few microbes where some codons are reassigned.
How it works
The genetic code groups codons into 64 three-nucleotide combinations: 61 encode the 20 standard amino acids and 3 are stop signals. Degeneracy means most amino acids are specified by more than one codon, and codons differing only in the third base often code for the same amino acid, a property called wobble. ATG (AUG in RNA) specifies Methionine and also serves as the start codon. Third-base degeneracy gives codon families shared first two bases: GCN = Alanine, CGN = Arginine. Codon-optimization algorithms exploit exactly this structure when rewriting a gene for a host's tRNA abundance without changing the protein.
Worked example
The codons CTT, CTC, CTA, CTG, TTA and TTG all code for Leucine, illustrating degeneracy. ATG codes for Methionine and is the start codon, while TAA, TAG and TGA are stops. A single base change can be silent (CTT → CTC, still Leucine), missense (CTT → CAT, changes to Histidine) or nonsense (TAC → TAG, creates a stop) — the table tells you which case you are in.
When to use it
Look up which codons encode a given amino acid when designing silent mutations. Confirm the amino acid for a codon found in a sequencing trace. Teach or learn the structure of the genetic code, toggling between DNA (T) and RNA (U) forms. When designing a synthetic gene, use the table to pick codons manually — e.g. choosing among the Arginine codons to avoid a forbidden restriction site inside the coding sequence.
FAQ
- How many codons are in the standard genetic code?
- There are 64 codons in total: 61 encode the 20 amino acids and 3 are stop signals.
- Which codon is the start codon and what does it code for?
- ATG, written AUG in RNA, is the start codon and it encodes Methionine.
- What are the three stop codons?
- TAA, TAG and TGA, written UAA, UAG and UGA in RNA, terminate translation.
- Why do multiple codons code for the same amino acid?
- The code is degenerate. Redundancy, especially at the third base position (wobble), lets several codons specify one amino acid and provides resilience to mutation.