When your cells use fat for energy the fatty acids are broken up into molecules of acetyl CoA. Predict how many ATP can be made from one molecule of acetyl CoA if oxygen is present. Show your work.?

One molecule of acetyl CoA enters the citric acid cycle (Krebs cycle), where it produces 3 NADH, 1 FADH2, and 1 ATP (or GTP). Each NADH can generate approximately 2.5 ATP and each FADH2 can produce about 1.5 ATP during oxidative phosphorylation. Thus, from one acetyl CoA:

• 3 NADH × 2.5 ATP/NADH = 7.5 ATP
• 1 FADH2 × 1.5 ATP/FADH2 = 1.5 ATP
• 1 ATP (from direct substrate-level phosphorylation)

Adding these together gives: 7.5 + 1.5 + 1 = 10 ATP. Therefore, one molecule of acetyl CoA can yield about 10 ATP when oxygen is present.