To determine the overall net gain of ATP in aerobic respiration per one molecule of glucose, let's go through the key stages involved in this metabolic process.
1. Glycolysis:
- This process occurs in the cytoplasm and breaks one molecule of glucose (a six-carbon compound) into two molecules of pyruvate (each a three-carbon compound).
- Net ATP gain: 2 ATP molecules (Since 4 ATP molecules are produced, but 2 ATP molecules are consumed during the process).
2. Pyruvate Oxidation and Citric Acid Cycle (Krebs Cycle):
- In the mitochondria, each pyruvate is converted into Acetyl-CoA, releasing one molecule of CO₂ and one NADH.
- The Acetyl-CoA then enters the Krebs Cycle, resulting in further production of NADH, FADH₂, and ATP.
- For each glucose molecule, the cycle runs twice (once for each pyruvate).
- Net ATP gain: 2 ATP molecules (one from each cycle).
3. Oxidative Phosphorylation (Electron Transport Chain and Chemiosmosis):
- NADH and FADH₂ produced during glycolysis, pyruvate oxidation, and the Krebs Cycle donate their electrons to the electron transport chain in the mitochondria.
- The movement of electrons drives the production of ATP via chemiosmosis.
- This stage produces the bulk of ATP in aerobic respiration.
- Net ATP gain: Approximately 26 to 34 ATP molecules.
Summarizing the above stages:
- Glycolysis: 2 ATP
- Krebs Cycle: 2 ATP
- Oxidative Phosphorylation: Approximately 26 to 34 ATP
When added together, the overall net gain of ATP ranges between 30 and 40 molecules per one molecule of glucose.
Thus, the correct answer is:
between 30-40
