Question

How many oxidative+substrate level ATP are produced from 2 pyruvic acid, if the ETC has only one H+ ion pump near the end?

answer is 12 but how?

Answer 1

Pyruvate is the end product of glycolysis. Under aerobic conditions, it enters the TCA cycle in the form of Acetyl CoA and gets oxidized to CO2.
One turn of the TCA cycle produces 3 NADH, 1 FADH2, and 1 ATP.
One glucose molecule = 2 Pyruvates = 2 Acetyl CoA = 6 NADH, 2 FADH2 and 2 ATP.

NADH and FADH2 enter the electron transport chain to produce ATP.
The ATP synthase complex utilizes proton gradient generated by electron carriers to couple ADp+Pi to produce ATP.

A WT ETC contains three pumps.
Hence 1 NADH produces 3 ATP.

If ETC contains only one pump,
6 NADH = 6 ATP
2 FADH2 = 2 ATP
2 ATP = 2 ATP

The transition reaction involves conversion of pyruvate to Acetyl CoA. This step generates one NADH.
Two pyruvates = 2 NADH = 2ATP

So, Total ATP = 12

Please provide a POSITIVE RATING. Thank you