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Oxidative Phosphorylation

OXIDATIVE PHOSPHORYLATION
Electron transport chain
  • Series of controlled redox reactions; pumps H+ into inter-membrane space
Chemiosmosis
  • Couples e- transport w/ ATP synthesis
ELECTRON TRANSPORT CHAIN
Complex I: NADH dehydrogenase
  • aka NADH-CoQ reductase
  • NADH delivers 2 electrons to the complex I and is oxidized to NAD+
CoQ (aka Q10 and ubiquinone)
  • Lipid-soluble
  • Mobile carrier
  • NOT a protein
Complex II: succinate dehydrogenase
  • aka Succinate-CoQ reductase
  • Also part of citric acid cycle
  • FADH2 delivers two electrons to complex II
Complex III: Cytochrome bc1 complex
  • aka CoQ-cytochrome c reductase
Cytochrome C
  • Water-soluble
  • Mobile carrier
Complex IV: cytochrome c oxidase
  • Produces one H2O from 2 H+ plus ½ O2 + 2e-
  • Complexes I, III & IV pump H+ from matrix to inter-membrane space
(NOT complex II, cyt. C or CoQ)
CHEMIOSMOSIS
Complex V: ATP synthase
  • Inner mitochondrial membrane IMPERMEABLE to most small molecules
  • H+ that is pumped across membrane cannot diffuse back through the bilayer
  • H+ diffuses down gradient through ATP synthase into the matrix
  • Produces 30-34 ATP per glucose molecule (NADH = 3 ATP, FADH2 = 2 ATP