Question

What happens during translation?

1 year ago

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Josie Roberts


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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:


  1. Ribosomes have 2 subunits, a small and a large. The mRNA attaches to the small subunit of the ribosome.
  2. 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.
  3. 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.
  4. 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.
  5. A peptide bond forms between the amino acid on the first tRNA and the amino acid on the second tRNA.
  6. The first tRNA molecule then detaches leaving the the dipeptide attached to the second tRNA molecule.
  7. 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.
  8. This process then continues unit a "STOP codon" is reached. The sequence of amino acids then detaches to be processed into a protein.
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