Question

2. What is the yield of ATP when one molecule of phosphoenolpyruvate is completely oxidized to CO2 by a mammalian cell? Assume that glycolysis, the citric acid cycle, and oxidative phosphorylation are fully active. Give a full and clear accounting of reduced cofactors and ATP equivalents to credit. A one-number answer will receive no credit.

Answer 1

The yield of ATP when one molecule of phosphoenolpyruvate is completely oxidized to
`CO_(2)` by a mammalian cell varies depending on the steps of glycolysis, the citric acid cycle, and oxidative phosphorylation.

Step-by-step explanation:

The yield of ATP when one molecule of phosphoenolpyruvate is completely oxidized to
`CO_(2)` by a mammalian cell depends on several factors including glycolysis, the citric acid cycle, and oxidative phosphorylation.

During glycolysis, 8 ATP are produced. Then, in the citric acid cycle, 6 ATP are produced from the oxidation of 2 pyruvate molecules.

In oxidative phosphorylation, the exact number of ATP molecules depends on whether the electrons are carried by NADH or
`FADH_(2)`. Each NADH molecule produced from the complete oxidation of glucose in glycolysis, the transition reaction, and the citric acid cycle can generate 3 ATP molecules, while each
`FADH_(2)` molecule can generate 2 ATP molecules. The theoretical maximum yield of ATP from the complete oxidation of glucose is 38 molecules, but the actual yield is usually less, ranging from 1 to 34 ATP molecules depending on other factors.