Which molecule is not a product of the Krebs cycle?

The Krebs cycle, also known as the citric acid cycle, is a key metabolic pathway that takes place in the mitochondria of the cells, where it plays a crucial role in cellular respiration. During this cycle, acetyl-CoA derived from carbohydrates, fats, and proteins is oxidized to produce energy-rich molecules.

NADH and FADH2 are both produced during the Krebs cycle as a result of the reduction of NAD+ and FAD, respectively. These molecules are essential electron carriers that help transport electrons to the electron transport chain, ultimately leading to ATP production. Additionally, carbon dioxide (CO2) is a byproduct of the cycle, released when the carbon atoms from acetyl-CoA are oxidized.

In contrast, glucose is not a product of the Krebs cycle. Instead, glucose is metabolized into pyruvate through a process called glycolysis before entering the Krebs cycle as acetyl-CoA. The cycle itself does not synthesize glucose; rather, it helps break down the products of glucose metabolism to generate energy. Thus, the correct identification of glucose as not being a product of the Krebs cycle reflects a fundamental understanding of cellular respiration and the metabolic pathways involved.