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The number in a cell depends on how much energy a cell needs. E.g.

  • Cardiac muscle cells ⟶ Need more energy ⟶ Have more mitochondria.

  • Fat cells ⟶ Need less energy ⟶ Have fewer mitochondria.


  • Rod-shaped or oval.

  • Made up of two membranes: Outer and inner membrane.

Outer Membrane
  • Smooth.

  • Covers the organelle.

Inner Membrane
  • Folded ⟶ forms shelves or tubules called cristae.

  • Contains oxidative enzymes.

  • Folding of the membrane increases its surface area ⟶ more enzymes can be accommodated.

  • Matrix inside the inner membrane contains more enzymes for energy metabolism.

Mitochondrial Genome
  • Circular DNA strands.

  • Encode some of the mitochondrial proteins.


Powerhouse of the cell

Extract energy from different nutrients

Converts it into ATP

Used as an energy sources for various reactions.

  • About 95% of total ATPs used by cells are produced in mitochondria.

Other Functions
  • A reservoir of Intracellular Calcium.

  • Participate in Apoptosis.


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