Electron transfer and oxidative phosphorylation Flashcards

1
Q

what happens in oxidative phosphorylation

A

the energy released from the oxidation os NADH and FADH2 is used to synthesize ATP

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2
Q

why use the Electron transport chain

A
  • reducing equivalents from reduced cofactors are passed to oxygen indirectly
  • reoxidation of NADH and FADH2 is broken up into processes with smaller free energy changes
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3
Q

what done the ETC comprise of

A
  • set of electron carriers arranged in order of increasing reduction potential
  • oxygen is the terminal e- acceptor
  • 4 unique enzymes (complexes) that catalyze transfer of e- form one carrier to another
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4
Q

complexes (enzymes)

A

I: NADH hydrogenase
II: succinate dehydrogenase
III: cytochrome c reductase
IV: cytochrome oxidase

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5
Q

coenzyme Q (ubiquinone)

A
  • can accept one e- (semiquinone .QH) or 2e- (ubiquinol QH2)
  • can freely move in the membrane, carrying e- from one ETC complex to another
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6
Q

cytochrome c

A
  • in the mitochondrial inter membrane space and shuttles e- from complex III to IV
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7
Q

ETC process

A
  • complex I and II transfer e- to Q, reducing it to QH2
  • QH2 passes electrons to cytochrome c through complex III
  • complex IV transfers e- from reduced cytochrome c to O2
  • electron flow through I, III and IV is accompanied by proton flow from the matrix to the IMS
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8
Q

CoQ collects reducing equivalents from…

A
  • complex I (NADH)
  • complex II (FADH2)
  • complex III (FADH2)- through a series of electron carriers
  • glycerol-3-phosphate dehydrogenase shuttle (FADH2)
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9
Q

proton gradient

A
  • conserves the energy available through the oxidation NADH and FADH2
  • for each pair of e- transferred from NADH to O2, 4 H+ from complex I, 4H+ from complex III and 2H+ by complex IV are pumped
  • electrons from FADH2 bypass complex I and 6 protons are pumped per FADH2
  • energy stored in the proton gradient is the proton motive force
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10
Q

what happens to the energy of the proton gradient in the presence of an uncoupler

A
  • the energy is not conserved by ATP formation so it dissipates as heat
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