Class 11 Biology Respiration In Plants Electron transport system

Electron transport system

  • The metabolic pathway through which the electron passes from one carrier to another, is called the electron transport system (ETS).
  • Electron transport system takes place in inner mitochondrial membrane.
  • Electron transport chain comprises of the following:
  • Complex I: NADH dehydrogenase
  • Complex II: succinate dehydrogenase
  • Complex III: cytochromes bc1
  • Complex IV: cytochromes a-a3
  • Complex V: ATP synthase
  • NADH2 is oxidized by NADH dehydrogenase and electrons are then transferred to ubiquinone located in the inner mitochondrial membrane.
  • FADH2 is oxidized by succinate dehydrogenase and transferred electrons to ubiquinone.
  • The reduced ubiquinone is then oxidized with transfer of electrons via cytochromes bc1 complex to cytochrome c.
  • Cytochrome c is a small protein attached to the outer surface of the inner membrane and transfer electrons from complex III to complex IV.
  • When electrons transferred from one carrier to another via complex I to complex IV, they are coupled to ATP synthesis of ATP from ADP and Pi.
  • Oxygen plays a vital role in removing electrons and hydrogen ion and finally helps in the production of H2


Fig. Electron transport chain

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