Translation

Transcription vs Translation

  • Transcription
    • RNA polymerase copies the mRNA of a gene
  • Translation
    • Ribosomes use the mRNA to create proteins

Ribosome

  • Ribosomes are complexes that are made out of rRNA (ribosomal RNA) and proteins
  • Have a large and small subunit
    • Subunit is a polypeptide chain or single protein molecule that assembles with others to form a protein complex

tRNA

  • Stands for transfer RNA
  • Small RNA molecules
  • Anti-codon that carries an amino acid
  • The amino acid that a tRNA carries is specific to its anti-codon

Three stages of translation

  1. Initiation
  2. Elongation
  3. Termination
Initiation
  • Small subunit binds to mRNA and scans for a start codon (AUG)
  • Large subunit assembles at the start of a codon
  • The ribosome binds a tRNA to the start codon
Elongation
  • Ribsosome slides across mRNA to the next codon
  • Adds new tRNA with complimentary anticodon
  • Ribsosome catalyses peptide bonds between the amino acids of adjacent tRNAs
  • As ribosome slides across “empty” tRNAs are released, the chain of amino acids remains and grow
Termination
  • Occurs when the ribosome reaches a stop codon
  • Releases peptide chain and causes ribosome subunits to dissociate