why are 34 ATP produced in oxidative phosphorylation?

Question

I know that each NADH produced 3 ATP and each FADH2 produces 2 ATP.
10 NADH + 2 FADH2 = 34 ATP

but I thought that the electrons were used to combine with oxygen to form water? or does it mean that 34 H+(protons) go down ATP Synthase and produces 34 ATP?

Answer 1

Given this one and your other earlier questions, you need to spend a little more time reading your text book and class notes.

As electrons are removed from NADH, the electrons are passed through the different complexes of the electron transport system. As these complexes gain and lose electrons, the complexes pump specific numbers of protons from the mitochondrial matrix into the intermembrane space, establishing a proton gradient across the inner mitochondrial membrane.

The electrons from NADH are transferred to oxygen, reducing it to water.

The protons that have been pumped out of the matrix flow back into the matrix through ATP synthase. This enzyme uses the energy released by the spontaneous flow of protons to drive the synthesis of ATP from ADP and phosphate.

The exact numbers of protons pumped by various complexes and the exact number of protons required to drive the synthesis of a single ATP are still being debated, but if your text uses the value of 3 ATP/ pair of electrons from NADH and 2 ATP/pair of electrons from FADH2, then use those numbers.

So, bottom line, movement of electrons through the ETS causes pumping of protons out of the matrix. The proton gradient drives the synthesis of ATP.

Answer 2

Oxidative phosphorylation is the production of ATP using energy derived from the transfer of electrons in an electron transport system and occurs by chemiosmosis.