DNA Codon Translator
Translate a DNA or RNA sequence into its amino acid chain.
5 codons translated
Met-Ala-Tyr-Cys-Stop
| # | Codon | Amino acid | Name |
|---|---|---|---|
| 1 | AUG | M · Met | Methionine (Start) |
| 2 | GCC | A · Ala | Alanine |
| 3 | UAU | Y · Tyr | Tyrosine |
| 4 | UGU | C · Cys | Cysteine |
| 5 | UAA | * · Stop | Stop (ochre) |
To translate DNA, read the sequence in triplets (codons): transcribe DNA to mRNA by swapping T for U, then map each three-base codon to its amino acid. For example, ATG GCA AAA TAA becomes AUG-GCA-AAA-UAA → Met-Ala-Lys-Stop, where AUG starts the protein and UAA ends it.
How codon translation works
The genetic code is read in triplets: every three bases form a codon that specifies one amino acid. This translator first transcribes DNA into mRNA by replacing every T with U, then reads the sequence three bases at a time in frame and maps each codon to its amino acid using the standard genetic code. A trailing partial codon (one or two leftover bases) is ignored.
Start and stop
AUG (methionine) is the start codon that usually begins a protein, while UAA, UAG, and UGA are the three stop codons that end translation. Turn on “stop at first stop” to halt translation at the first stop codon, just as the ribosome does.
Worked example
Translate the DNA sequence ATG GCA AAA TAA:
- 1 Transcribe DNA to mRNA. Replace every T with U: ATGGCAAAATAA → AUGGCAAAAUAA.
- 2 Split into codons of three bases. AUG · GCA · AAA · UAA.
- 3 Map each codon to an amino acid. AUG → Met (start), GCA → Ala, AAA → Lys, UAA → Stop.
- 4 Read off the peptide. Met–Ala–Lys, then translation stops at UAA. In one-letter code: M-A-K.
Representative codons (standard genetic code)
A subset of the 64 codons, including the start codon and all three stops; mRNA uses U in place of T.
| Codon | Amino acid | 3-letter | 1-letter |
|---|---|---|---|
| AUG | Methionine (Start) | Met | M |
| UUU | Phenylalanine | Phe | F |
| UGG | Tryptophan | Trp | W |
| GCA | Alanine | Ala | A |
| GGU | Glycine | Gly | G |
| AAA | Lysine | Lys | K |
| GAA | Glutamate | Glu | E |
| UAA | Stop (ochre) | Stop | * |
| UAG | Stop (amber) | Stop | * |
| UGA | Stop (opal) | Stop | * |
Reading frames, redundancy, and pitfalls
Reading frame matters. The tool reads frame 1, starting at the very first base. Shifting the start by one or two bases gives entirely different codons and a different protein, so frame choice is critical when you don’t know where translation begins.
The code is redundant. With 64 codons for 20 amino acids plus stops, most amino acids have several codons. Leucine, serine, and arginine each have six. This is why a DNA change can be “silent” and leave the protein unchanged.
Common mistakes. Don’t forget to transcribe T to U before reading mRNA codons, and watch the frame — a single inserted or deleted base shifts every codon downstream (a frameshift). A length that isn’t a multiple of three simply leaves a partial codon at the end, which is dropped.