Translation follows transcription and is the second stage of protein synthesis. Translation occurs in ribosomes and is the process of mRNA be "translated" into a sequence of amino acids. The sequence of mRNA is synthesised during transcription from a sequence of DNA called a gene. The mRNA then travels to a a ribosome and the following sequence of events occurs:
- Ribosomes have 2 subunits, a small and a large. The mRNA attaches to the small subunit of the ribosome.
- The beginning of the mRNA is called a start codon and consists of 3 RNA bases (e.g. AUG). A molecule of tRNA which has a specific amino acid attached to it then attaches to the large subunit of the ribosome in the first tRNA binding site.
- The tRNA has an "anti-codon" which has complementary bases to the first codon. Therefore, the mRNA and tRNA bind by complementary base pairing using hydrogen bonds.
- A second tRNA molecule with a specific amino attached to it then binds to the second tRNA binding site which is adjacent to the first tRNA binding site in the ribosome.
- A peptide bond forms between the amino acid on the first tRNA and the amino acid on the second tRNA.
- The first tRNA molecule then detaches leaving the the dipeptide attached to the second tRNA molecule.
- The second tRNA molecule then shifts to the first tRNA binding site and a 3rd tRNA molecule attaches to the 2nd tRNA binding site in the ribosome and a peptide bond is formed between the dipeptide and the amino acid on the 3rd tRNA molecule.
- This process then continues unit a "STOP codon" is reached. The sequence of amino acids then detaches to be processed into a protein.