Where does oxidation of fatty acids for ATP production occur?

• A. Red blood cells
• B. Adipocyte mitochondria only
• C. Cells that contain mitochondria
• D. The bloodstream

Answer: (C)

Fatty acid oxidation for ATP relies on the mitochondrial beta-oxidation pathway and the subsequent oxidative phosphorylation that takes place in mitochondria. Cells that have mitochondria can perform this process, using fatty acids to generate acetyl-CoA, NADH, and FADH2 which feed into the TCA cycle and electron transport chain to produce ATP.

Red blood cells lack mitochondria, so they can’t oxidize fatty acids for ATP and rely on glycolysis instead. Adipocytes do have mitochondria, but the key point is that any cell with mitochondria can carry out fatty acid oxidation, not just adipose tissue. The bloodstream doesn’t contain organelles, so oxidation cannot occur there. Peroxisomes can start the oxidation of very long-chain fatty acids, but ATP production ultimately depends on mitochondrial oxidation. Therefore, the correct description is oxidation occurs in cells that contain mitochondria.