Question

A fatty acid composed of 20 carbon atoms undergoes β‑oxidation.

How many acetyl CoA, FADH2, and NADH does β‑oxidation of this fatty acid generate? (answer is 10 acetyl CoA, 9 FADH2, 9 NADH)

Calculate the net ATP generated by the β‑oxidation of the 20‑carbon fatty acid. Assume that each FADH2 generates 1.5 ATP and each NADH generates 2.5 ATP.

number of ATP molecules: ??????

Answer 1

A 20 carbon fatty acid produces 10 acetyl CoA, 9 FADH₂, 9 NADHin β‑oxidation.

The Total ATP production of fatty acid:

	Reaction	ATP yield	ATP consumed
TCA cycle	Activation of fatty acid to fatty acyl CoA		-2
	Oxidation of 10 acetyl CoA	10GTP=10 10 FADH2 = 1.5×10 = 15 30 NADH2 = 2.5×30 = 75
Oxidation cycle	Oxidation of 9 FADH2	1.5×9 = 13.5
	Oxidation of 9 NADH	2.5×9 = 22.5
	Total ATP produced	136-2 = 134

After complete β-oxidation of fatty acid, the no. of ATP produced is 134.