Sunday 9 June 2013

Translation of the Genetic Code: Protein Synthesis


  • Messenger RNA is made in the nucleus by transcription from a DNA molecule. 
  • A ribosome on the rough endoplasmic reticulum (RER) attaches to the mRNA molecule.
  • A transfer RNA molecule arrives and brings an amino acid to the first three bases (codon) on the mRNA.
  • The three unpaired bases (anticodon) on the tRNA link up with the codon.
  • Another tRNA molecule comes into place bringing a second amino acid
  • Its anticodon links up with the second codon (next three bases) on the mRNA
  • A peptide bond is formed between the two amino acids
  • The first tRNA molecule releases its amino acid and moves off into the cytoplasm
  • The ribosome moves along the mRNA to the next codon
  • Another tRNA molecules bring in the next amino acid into place
  • A peptide bond joings the second and third amino acid to form a polypeptide chain
  • The process continues - polypeptide chain gets longer, this continues until termination (stop) codon is reached then the polypeptide is complete

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