18.4 - Oxidative Phosphorylation

Question 1

Explain the process of oxidative phosphorylation

Answer 1

1. NADH and FADH₂ from the Krebs Cycle are present in the matrix, they release H⁺ and high energy e^-
2. The e^- are reduce and oxidise electron carriers in the ETC. The electrons release energy and each complex uses that energy to pump protons across the membrane into the intermembrane space
3. There is then a high proton concentration gradient in the IM.
4. The protons diffuse down the electrochemical proton gradient through ATP synthase to generate ATP molecules
5. The build up of protons lowers the pH affecting respiratory enzymes, so oxygen is known as the terminal electron acceptor to form water

ADP phosphorylation can only occur if electrons move along the ETC, and it also requires the presence of oxygen to accept the electrons

Question 2

Define substrate level phosphorylation

Answer 2

Production of ATP involving the transfer of a phosphate group from a highly reactive unstable intermediate, creatine phosphate – different to oxidative phosphorylation