1.5.3 Ribosomes

Structure of Ribosomes:

• Composition: Ribosomes are made up of ribosomal RNA (rRNA) and proteins.
• Subunits: Each ribosome consists of two subunits:
  • Large Subunit: Responsible for forming peptide bonds between amino acids.
  • Small Subunit: Binds to mRNA and reads its sequence during translation.
• Location: Ribosomes can be found:
  • Free in the cytoplasm (where they synthesise proteins for use within the cell).
  • Attached to the rough endoplasmic reticulum (RER) (where they synthesise proteins for export or for use in the cell membrane).

Function of Ribosomes:

• Translation of mRNA: Ribosomes use the information in messenger RNA (mRNA) to assemble amino acids into a specific sequence, creating a polypeptide chain that will fold into a functional protein.
• Role in Protein Synthesis: Ribosomes facilitate the formation of peptide bonds between amino acids, building the primary structure of proteins. Ribosomes are essential for cell function because they enable the translation of genetic information into proteins, which are necessary for structure, enzymes, signalling, and other cellular processes.