Translation

Translation is the synthesis of the polypeptide/protein whose structure is governed by the sequence determined by the mRNA codons. The process occurs at the ribosomes where the large subunit of the ribosome attaches the mRNA and once the small ribosomes attaches the mRNA sequence gets translated into amino acids.

Steps in translation

  1. Translation occurs in groups of three known as a codon. Each codon codes for either an amino acid or stop codon.
  2. The first codon of the mRNA is always AUG (methionine) signaling the beginning of polypeptide/protein synthesis.
  3. The entire protein is coded by the many codons in the mRNA template until a stop codon occurs.
  4. The amino acids exist in the cytosol of the cells, which are either synthesized by the body or obtained from our diet. A transfer RNA (tRNA) has anticodons that will bind complementary temporarily to the codons on the mRNA sequence bringing in a specific amino acid unless it is a stop codon.
  5. When the codon and anticodon pair the amino acid is deposited and a peptide bond forms between the amino acid forming a growing polypeptide chain.
  6. Ultimately a stop codon will be reached, whereby release factor occupies the codon site and the amino acid and its tRNA molecule is broken and the completed polypeptide is released.

Codon table

600px-Codontable2((http://openwetware.org/wiki/CH391L/S12/TranslationRBSandCodons))

Click to enlarge

  • Be familiar how to use the table, but you do not need to memorise it!
  • VCAA will give it to you if required.
  • Also, be sure to check whether the codes are in RNA or DNA.