What is the net gain of ATP from cellular respiration as given?

What is the net gain of ATP from cellular respiration as given?

• A. 20-24 ATP
• B. 4 ATP
• C. 60-70 ATP
• D. 36-38 ATP

Answer: (D)

The main idea here is how much ATP is produced from one glucose molecule during cellular respiration and why that number isn’t fixed. Most of the energy comes from oxidative phosphorylation in the mitochondria, where NADH and FADH2 generated in glycolysis, pyruvate oxidation, and the citric acid cycle feed electrons into the electron transport chain to pump protons and drive ATP synthase. The exact total ATP depends on two practical details: how many ATP you count per NADH and how the cytosolic NADH from glycolysis gets into the mitochondria (shuttle systems). Depending on the shuttle used, a cytosolic NADH can contribute differently to the ATP tally, and the accepted textbook figures round to about 36–38 ATP per glucose in many eukaryotic cells. Other numbers arise from using different shuttle assumptions or different ATP yields per NADH/FADH2, which is why you’ll see a range in different sources.

The main idea here is how much ATP is produced from one glucose molecule during cellular respiration and why that number isn’t fixed. Most of the energy comes from oxidative phosphorylation in the mitochondria, where NADH and FADH2 generated in glycolysis, pyruvate oxidation, and the citric acid cycle feed electrons into the electron transport chain to pump protons and drive ATP synthase. The exact total ATP depends on two practical details: how many ATP you count per NADH and how the cytosolic NADH from glycolysis gets into the mitochondria (shuttle systems). Depending on the shuttle used, a cytosolic NADH can contribute differently to the ATP tally, and the accepted textbook figures round to about 36–38 ATP per glucose in many eukaryotic cells. Other numbers arise from using different shuttle assumptions or different ATP yields per NADH/FADH2, which is why you’ll see a range in different sources.