How many ATP are produced from one turn of the Krebs Cycle?

The Krebs Cycle, also known as the citric acid cycle or TCA cycle, primarily generates energy through the oxidation of acetyl-CoA. In one turn of the Krebs Cycle, a single molecule of ATP (or its equivalent, GTP) is produced directly. This occurs through substrate-level phosphorylation, where a phosphate group is transferred to ADP (or GDP) from a substrate with a high-energy phosphate bond.

While additional energy carriers such as NADH and FADH2 are produced in the process, which will later contribute to ATP production during oxidative phosphorylation, the direct output from one complete turn is indeed one ATP. Therefore, identifying that one turn of the Krebs Cycle yields one ATP directly aligns with the fundamental biochemistry of cellular respiration.