Describe the cell membrane and cellular organelles and their properties

Organelles are specialised functional subunits within a cell, typically contained within their own lipid bilayer.

Key organelles include:

  • Mitochondria
  • Endoplasmic reticulum
  • Golgi apparatus



  • Produce ATP via aerobic metabolism
    Only method of aerobic metabolism in the body.
    • Mitochondria exist in greater numbers in more metabolically active cells
  • Consist of two membranes (outer and inner), which create three spaces,
    • Cytoplasm
      Outside the outer membrane.
    • Intermembrane space
      Between the membranes.
      • Outer membrane separates mitochondria from cytoplasm, but contains pores allowing some substances (pyruvate, amino acids, fatty acids) to pass
      • Inner membrane:
        • Isolates the electron transport chain from the intermembrane (space between inner and outer membranes) space.
        • Proteins on the inner membrane conduct the redox reactions important for ATP production
        • Electron transport chain pumps hydrogen ions into the intermembrane space
    • Inner mitochondrial matrix
      Contents important in many metabolic processes:
      • Citric acid cycle
      • Fatty acid metabolism
      • Urea cycle
      • Haeme synthesis


  1. Chambers D, Huang C, Matthews G. Basic Physiology for Anaesthetists. Cambridge University Press. 2015.
Last updated 2019-07-18

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