Endoplasmic Reticulum

The Endoplasmic Reticulum is an organelle that forms an interconnected network of membrane vesicles.


There are three different types of ERs:

  • Rough Endoplasmic Reticulum (RER)
    • Has ribosomes attached to the outside
    • These ribosomes synthesise protein
    • Connects to the Nuclear Envelope
  • Smooth Endoplasmic Reticulum (SER)
    • Produces lipids
    • Cholesterol metabolism
    • Lipids are sent to golgi in vesicles
  • Sarcoplasmic Reticulum (SR)
    • An SER found in smooth and striated muscle


  • Many general functions - can adapt to what the organism needs
  • e.g.
    • Production of hormones
    • Cholesterol metabolism
    • Membrane synthesis
    • Lipid production