Polypeptide Synthesis – Translation

Once mRNA has passed out of the nuclear pore, it determines the synthesis of a polypeptide.


  1. A ribosome attaches to the starting codon, at one end of an RNA molecule.
  2. The tRNA molecule with a complementary anticodon sequence moves to the ribosome,  and pairs up with the sequence on the mRNA.
  3. A tRNA molecule with a complimentary anticodon pairs up with the next codon on the mRNA.
  4. The ribosome moves along the mRNA, bringing together two tRNA molecules, each pairing up with the corresponding two codons on the mRNA.
  5. By means of an enzyme, ATP and and two amino acids on the tRNA are joined by a peptide bond.
  6. The ribosome moves onto the third codon, on the mRNA linking the amino acids.
  7. As this happens the first tRNA is released from its amino acid, from the amino acid pool in the cell.
  8. This process continues until a complete polypeptide chain is created.