How many ATP molecules can be produced from one cycle of the citric acid cycle?

The citric acid cycle, also known as the Krebs cycle or TCA cycle, is a crucial metabolic pathway that generates energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. During one complete turn of the citric acid cycle, a variety of high-energy electron carriers are produced, specifically NADH and FADH2, along with a single molecule of GTP, which can readily be converted to ATP.

For each acetyl-CoA that enters the cycle, three NADH molecules and one FADH2 molecule are produced, in addition to one ATP (or GTP, which is equivalent for energy purposes). The electron carriers (NADH and FADH2) play a significant role in the electron transport chain, which is where ATP production is finalized.

To quantify the ATP yield from the electron carriers:

• Each NADH can produce about 2.5 ATP in the electron transport chain.

• Each FADH2 produces about 1.5 ATP.

So, from one cycle:

• Three NADH contribute approximately 3 x 2.5 = 7.5 ATP.

• One FADH2 contributes about 1.5 ATP.

• Adding the ATP generated directly