Organelles

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

Mitochondria

Mitochondria:

• 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

References

1. Chambers D, Huang C, Matthews G. Basic Physiology for Anaesthetists. Cambridge University Press. 2015.