How many ATP molecules are produced net from one glucose molecule during cellular respiration?

The correct answer is that cellular respiration produces a net of 36 ATP molecules from one molecule of glucose under ideal conditions. During the process of aerobic cellular respiration, glucose undergoes glycolysis, the citric acid cycle, and oxidative phosphorylation.

In glycolysis, which occurs in the cytoplasm, two ATP molecules are consumed, but four ATP molecules are produced, resulting in a net gain of two ATP. The pyruvate produced then enters the mitochondria, where it is converted into acetyl-CoA and enters the citric acid cycle. Each turn of the citric acid cycle produces three NADH, one FADH2, and one ATP (or GTP). Since each glucose molecule generates two acetyl-CoA, the cycle turns twice, resulting in six NADH, two FADH2, and two ATP from one glucose molecule.

The NADH and FADH2 produced during these processes then enter the electron transport chain, where they are used to create a proton gradient that drives the synthesis of ATP through oxidative phosphorylation. Each NADH can yield approximately 2.5 ATP, and each FADH2 can yield about 1.5 ATP.

When these numbers are summed:

• From glycolysis: