Electron Transport Chain

Purpose of ETC

Use electrons from NADH and FADH₂ to make ATP via oxidative phosphorylation.

Location of ETC

Inner mitochondrial membrane (cristae).

Final electron acceptor in ETC

Oxygen (O₂), forming water.

Complex I

Accepts electrons from NADH, pumps H⁺.

Complex II

Accepts electrons from FADH₂, no H⁺ pumped.

Coenzyme Q

Transfers electrons to Complex III.

Complex III and Cytochrome c

Pass electrons to Complex IV.

Complex IV

Transfers electrons to O₂, forming H₂O.

Chemiosmosis

Flow of H⁺ through ATP synthase drives ATP formation.

Proton motive force

H⁺ gradient that stores potential energy for ATP synthesis.

ATP synthase

Enzyme that makes ATP using the proton gradient.

ATP yield per NADH

~3 ATP.

ATP yield per FADH₂

~2 ATP.

Total theoretical ATP per glucose

~38 ATP (bacteria), ~36 ATP (eukaryotes).