Yees

• Translation


  Process of polymerisation of amino acids to form a polypeptide
• The order and sequence of amino acids are defined by the sequence of bases in the mRNA
• Formation of a peptide bond

  1. Amino acids are activated in the presence of ATP and linked to their cognate tRNA (aminoacylation)

  2. Charged tRNAs are brought close enough for the peptide bond to form
• Ribosome


  Cellular factory responsible for synthesising proteins, consisting of structural RNAs and about 80 different proteins
• Ribosome

  • Has two subunits - a large subunit and a small subunit
  • The small subunit encounters an mRNA to begin translation
  • Has two sites for subsequent amino acids to bind and form a peptide bond
  • Acts as a catalyst (23S rRNA in bacteria is the enzyme- ribozyme) for the formation of peptide bond
• Translational unit in mRNA

  Sequence of RNA flanked by the start codon (AUG) and the stop codon, coding for a polypeptide
• Untranslated regions (UTRs)

  Additional sequences in mRNA that are not translated, present at both 5'-end (before start codon) and at 3'-end (after stop codon), required for efficient translation process
• Initiation of translation

  1. Ribosome binds to the mRNA at the start codon (AUG) recognised only by the initiator tRNA

  2. Ribosome proceeds to the elongation phase
• Elongation phase of translation

  1. Complexes of amino acid linked to tRNA sequentially bind to the appropriate codon in mRNA by forming complementary base pairs with the tRNA anticodon

  2. Ribosome moves from codon to codon along the mRNA, adding amino acids one by one to form the polypeptide sequence
• Termination of translation

  A release factor binds to the stop codon, releasing the complete polypeptide from the ribosome