Mitochondria are the ‘powerplants’ of the cell – synthesising large amounts of ATP via aerobic respiration

• All eukaryotic cells possess mitochondria – certain prokaryotes use the cell membrane to respire aerobically

Mitochondria are thought to have once been independent prokaryotes that were internalised via endosymbiosis

• They have a double membrane structure (due to vesicular coating as part of the endocytotic process)
  

• They have their own DNA (circular and naked) and ribosomes (70S)
  

• Their metabolic processes are susceptible to certain antibiotics
  

The structure of the mitochondrion is adapted to the function it performs:

• Outer membrane – the outer membrane contains transport proteins that enable the shuttling of key materials from the cytosol

• Inner membrane – contains the electron transport chain and ATP synthase (used for oxidative phosphorylation)

• Cristae – the inner membrane is arranged into folds (cristae) that increase the SA:Vol ratio (more available surface area)

• Intermembrane space – small space between membranes maximises hydrogen gradient upon proton accumulation

• Matrix – central cavity that contains appropriate enzymes and a suitable pH for the Krebs cycle to occur

Structure of a Mitochondrion