Last reviewed 01/2018

Ribosomes are composed of ribosomal RNA derived from nuclear DNA. They are particulate structures found:

  • on the surface of the rough endoplasmic reticulum, often joined together by strands of messenger RNA - polyribosomes
  • free within the cytoplasm - polysomes

They function in protein synthesis by:

  • acting as a site for the junction of messenger RNA and transfer RNA
  • catalyzing the formation of a peptide bond in the growing peptide chain
  • ensuring the correct site of initiation and termination of the peptide chain