Protein Synthesis: Translation

This lesson covers: 

  1. Where translation takes place
  2. The process of translation

The process of translation

Translation occurs in the cytoplasm, specifically on the ribosome in both eukaryotic and prokaryotic cells.


Translation is the process of decoding the information in messenger RNA (mRNA) to synthesise a polypeptide chain, with the help of transfer RNA (tRNA). This chain then folds into a functional protein.

Diagram illustrating the process of translation with mRNA, tRNA, ribosome, codons, anticodons, peptide bonds, and a growing polypeptide chain.

Translation involves several key steps:

  1. The ribosome attaches to the mRNA strand at a start codon (AUG).
  2. A tRNA molecule, carrying a specific amino acid and with an anticodon (UAC) that is complementary to the start codon, binds to the mRNA.
  3. A second tRNA molecule with an anticodon complementary to the next mRNA codon, and also carrying a specific amino acid, attaches to mRNA.
  4. The amino acids carried by the first two tRNA molecules are linked together via a peptide bond using ATP.
  5. The first tRNA molecule detaches from mRNA and is free to collect another amino acid for future use.
  6. The ribosome moves along mRNA, allowing another tRNA molecule, which carries the next amino acid, to bind to the next codon on the mRNA.
  7. The process from step 4 to 6 is repeated, which elongates the polypeptide chain.
  8. At any point during this process, two tRNA molecules can be attached to mRNA.
  9. The sequence continues until a stop codon on the mRNA is reached, at which point the completed polypeptide chain detaches from the ribosome.