Question

Which of the following sets is most correct for the catabolism of an 18-carbon fatty acid?

• A. Mitochondria, beta oxidation, 140 ATP molecules
• B. Cytosol, beta oxidation, 146 ATP molecules
• C. Mitochondria, beta oxidation, 146 ATP molecules
• D. Cytosol, beta oxidation, 140 ATP molecules

Answer 1

The correct option is C Mitochondria, beta oxidation, 146 ATP molecules

Fatty acid catabolism involves three stages. The first stage of fatty acid catabolism is beta oxidation in the mitochondria. The second stage is acetyl CoA oxidation to carbon dioxide. The third stage is electron transfer from electron carriers to the electron transfer chain. For an even numbered saturated fat (in which number of carbon is 2n), n - 1 oxidations are necessary for its complete oxidation.

The total ATP yield can be stated as: (n - 1) * 17 + 12 - 2 .

Thus, here 2n $=$ 18, n $=$ 9

Then the total number of ATP yield is 9 * 17 + 12 - 2 $=$ 146