Multiple choice

What is the net yield of complete oxidation of stearic acid?

  1. 129 ATP

  2. 146 ATP

  3. 131 ATP

  4. 148 ATP

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

8 cycles of beta oxidation = 8 x 5 = 40 ATP, 9 acetyl Co-A entering into the TCA cycle = 9 x 12 = 108 ATP. 2 ATPs are utilised for activation of stearic acid to stearyl Co-A. So, net yield is = (108 + 40) - 2 = 146 ATP.

AI explanation

Stearic acid (C18:0) undergoes 8 rounds of beta-oxidation, producing 9 acetyl-CoA, 8 FADH2, and 8 NADH. Using the classical ATP yields (3 ATP per NADH, 2 ATP per FADH2, and 12 ATP per acetyl-CoA through the TCA cycle), the gross yield is 148 ATP, and subtracting the 2 ATP equivalents used for fatty acid activation gives a net yield of 146 ATP.