8.2  Cell Respiration

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Essential Idea:

Energy is converted to a

usable form in cell respiration


  • Cell respiration involves the oxidation and reduction of electron carriers
  • Phosphorylation of molecules makes them less stable
  • In glycolysis, glucose is converted to pyruvate in the cytoplasm
  • Glycolysis gives a small net gain of ATP without the use of oxygen
  • In aerobic cell respiration pyruvate is decarboxylated and oxidised, and converted into acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction
  • In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers, liberating carbon dioxide
  • Energy released by oxidation reactions is carried to the cristae of the mitochondria by reduced NAD and FAD
  • Transfer of electrons between carriers in the electron transport chain in the membrane of the cristae is coupled to proton pumping
  • In chemiosmosis protons diffuse through ATP synthase to generate ATP
  • Oxygen is needed to bind with the free protons to maintain the hydrogen gradient, resulting in the formation of water
  • The structure of the mitochondrion is adapted to the function it performs


  • Electron tomography used to produce images of active mitochondria


  • Analysis of diagrams of the pathways of aerobic respiration to deduce where decarboxylation and oxidation reactions occur
  • Annotation of a diagram of a mitochondrion to indicate the adaptations to its function