Oxidative phosphorylation

• Takes place in inner mitochondrial membrane

• Results in production of many molecules of ATP and production of water for oxygen

• Chemiosmotic theory

  • Energy from electrons passed through a chain of proteins in the membrane (electron transport chain) via a series of redox reactions is used to pump protons (H⁺ ions) up their concentration gradient into the intermembrane space

  • H⁺ ions then flow by facilitated diffusion through a channel in ATP synthase into the matrix

  • Energy of the hydrogens flowing down concentration gradient harnessed which results in phosphorylation of ADP into ATP by ATP synthase

The electron transport chain

• Made up of a series of membrane proteins/electron carriers

• Positioned close together - allows electrons to pass from carrier to carrier

• Inner membrane impermeable to H⁺ so electron carriers required to pump protons across the membrane to establish concentration gradient

• Oxygen acts as final electron acceptor

  • Without oxygen accepting the electrons electrons won’t have anywhere to go

  • NADH and FADH₂ cannot be oxidised to regenerate NAD and FAD, so they can’t be used in further hydrogen transport

Theoretical yield = 38 ATP per glucose molecule but rarely achieved due to inner mitochondrial memrane being leaky to H+ therefore not all H