Electron transport chain and Oxidative phosphorylation Animation


  1. Mitochondrial Respiratory or Electron transfer chain is located in inner mitochondrial membrane
  2. Substrate are oxidized and e- released passes from Complex of low redox potential to higher redox potential, eventually being added to O2 at complex IV to form H2
  3. At complex I, III and IV, energy generated is used to proton pump (H+) inner mitochondrial membrane (Coupling sites/ Sites of ATP generation coupled with oxidative phosphorylation) 
  4. Oxidative phosphorylation: The proton gradient so created is released by passing protons back across inner membrane throught the ATP synthase (Complex V) resulting in ATP generation from ADP (3 for NADH – Complex I, III and IV and 2 for FADH2 – Complex III and IV i.e. Complex I bypassed) 
  • Complex I (NADH dehydrogenase)
  • Complex II (Succinate dehydrogenase) 
  • Complex III (Cytochrome C reductase) 
  • Complex IV (Cytochrome C Oxidase)
  • Complex V (ATP synthase) 

         NADH Complex I Q Complex III cytochrome c  Complex IV  → O2
                        Complex II 

Inhibitors of Respiratory chain:
  1. Complex I : Barbiturate, Piericidin
  2. Complex II: Carboxin, M
  3. Complex III: BAL, Antimycin
  4. Complex IV: Cyanide, Carbon monoxide
Cyanide poisoning:
  1. Binds irreversibly to cytochrome a/a3 (complex IV) preventing electron transfer to oxygen, producing many of the same changes seen in tissue hypoxia. 
  2. Sources of cyanide include: Burning polyurethane (foam stuffing in furniture and mattresses) and Byproduct of nitroprusside (released slowly; thiosulfate can be used to destroy the cyanide)
  3. Nitrites may be used as an antidote for cyanide poisoning if given rapidly. They convert hemoglobin to methemoglobin, which binds cyanide in the blood before reaching the tissues. Oxygen is also given if possible.

Inhibitors of Oxidative phosphorylation:
  1. Uncouplers (Shunts H+ preventing pumping by ATP synthase) : 2,4 Dinitrophenol (2,4 DNP), thyroxine, thermogenin in brown fat
  2. Inhibitors of ATP translocase: Atractyloside
  3. Inhibitor of ATP synthase: Oligomycin

Respiratory control:

When Oxygen is limited:

O2 ↓oxidative phosphorylation ↑[NADH] & [FADH2] → (-)TCA cycle

When Oxygen is adequate:

↑[ADP] → (+)isocitrate dehydrogenase ↑TCA ↑[NADH] & [FADH2] →   ↑electron transport  ↑[ATP]


1 comment :

  1. I like it very interesting and easy to understand for my pupils.so thank


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