Question

NADH can be used to make 2.5 ATP while FADH2 can only make 1.5 ATP. How exactly is this difference accomplished in the mitochondria?

Answer 1

Hey there,

By the process of the electron transport chain, the electrons are transported via mitochondrial complexes to the last oxygen acceptor, and thus the proton motive force generated is utilized to generate ATP from enzyme ATP synthase.

In order to move the electrons from NADH to last oxygen acceptor, a total of 10 protons are transported from matrix to inner mitochondrial membrane, to generate a proton motive force.

4 protons via complex I

4 via complex III

2 via complex IV

To make 1 ATP, 4 protons move from inter mitochondrial membrane to the matrix via ATPase.

Therefore for NADH— 10/4=2.5 ATP is produced from 1 NADH.

Similarly, for 1 FADH2, 6 protons are moved from matrix to the inner mitochondrial membrane, to generate a proton motive force.

Therefore, 6/4= 1.5 ATP is produced from 1 FADH2.