DNA to protein translator
Paste a sequence to see the mRNA, the codons, and the amino acid chain.
From gene to protein
Transcription copies DNA into mRNA, swapping thymine (T) for uracil (U). Translation then reads the mRNA three bases at a time. Each codon codes for one amino acid, and three codons (UAA, UAG, UGA) signal stop.
A coding strand has the same sequence as the mRNA, except T becomes U. A template strand is complementary, so the tool builds the mRNA by pairing each base. Real genes also have introns and untranslated regions that this simple tool doesn’t model.
Worked example
Take the coding strand 5′-ATG GCC TTT TAA-3′. Transcription makes mRNA with the same sequence but U in place of T: AUG GCC UUU UAA. Reading the codons with the genetic code gives Met – Ala – Phe – stop.
If you’re given the template strand instead, 3′-TAC CGG AAA ATT-5′, each base pairs with the mRNA (A–U, T–A, C–G, G–C), which gives the same mRNA. Choose the matching sequence type in the tool so it reads the strand correctly.
Frequently asked questions
What is the difference between the coding and template strands?
The template strand is the one RNA polymerase reads. The coding strand has the same sequence as the mRNA (with T instead of U), so it’s the strand usually written in textbooks and databases.
What are the start and stop codons?
AUG codes for methionine and is the usual start codon. UAA, UAG and UGA are the stop codons; they don’t code for an amino acid and end translation.
What is a reading frame?
The way a sequence is split into groups of three. Starting one base later changes every codon, so the same sequence can be read in three frames. Frames 2 and 3 in the tool shift the start by one and two bases.
Why do several codons code for the same amino acid?
There are 64 codons but only 20 amino acids, so most amino acids have more than one codon. This redundancy means some mutations, especially in the third base, don’t change the protein.