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Which molecule is produced for each acetyl CoA that enters the Krebs Cycle?

  1. 1 ATP

  2. 3 NADH

  3. FADH2

  4. GTP

The correct answer is: 1 ATP

In the Krebs Cycle, also known as the citric acid cycle or TCA cycle, each molecule of acetyl CoA that enters results in the production of multiple high-energy carriers. Specifically, for each acetyl CoA processed, three molecules of NADH and one molecule of FADH2 are generated, along with one molecule of GTP or ATP. While GTP is structurally similar to ATP and is used in some cells as an energy currency, the primary focus on the production of high-energy molecules points towards the significant role of the NADH and FADH2 generated during the cycle. These carriers are crucial for the electron transport chain, ultimately leading to the generation of ATP through oxidative phosphorylation. Thus, the most accurate and relevant answer emphasizes the extensive generation of NADH and FADH2, rather than just focusing on the production of ATP or GTP. Each acetyl CoA effectively produces three NADH, one FADH2, and one GTP, illustrating the energy yield from this essential metabolic pathway.