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