Organelles & the Production of Proteins (OCR A Level Biology): Revision Note

Organelles & the production of proteins

• Inside cells multiple organelles are involved in the production and secretion of proteins

• Organelles involved in protein production, and their roles, include:

  • nucleus

    • DNA is stored

    • The nucleolus manufactures ribosomes

    • Transcription occurs, during which an mRNA copy of DNA is produced

  • ribosomes

    • mRNA leaves the nucleus and attaches to a ribosome

    • Translation occurs, during which a chain of amino acids is produced; this chain is known as a polypeptide

  • rough endoplasmic reticulum (RER)

    • Many ribosomes are attached to the surface of this organelle

    • After translation the polypeptides are folded and processed to produce proteins

  • Golgi apparatus

    • Proteins are modified and prepared for secretion

  • vesicles

    • Proteins are transported from the RER to the Golgi apparatus, and from the Golgi apparatus to the cell surface membrane inside vesicles

    • Vesicles fuse with the cell surface membrane to secrete proteins, e.g. hormones, from the cell by exocytosis

• Cells that produce many proteins, e.g. within hormone-producing glands, or in the enzyme-producing cells of the digestive system, will have many of the organelles that are involved with protein production

Organelles in protein production diagram

Multiple cellular structures are involved in the production and secretion of proteins