What molecules are reduced during the Krebs Cycle?

During the Krebs Cycle, also known as the citric acid cycle or TCA cycle, specific molecules play critical roles in the processes of oxidation and reduction. The primary molecules that are reduced in this cycle are NAD+ and FAD.

NAD+, which is reduced to NADH, and FAD, which is reduced to FADH2, serve as cofactors that accept electrons during specific reactions within the Krebs Cycle. These reductions occur at various steps in the cycle, as acetyl-CoA is processed through a series of enzymatic reactions resulting in the production of NADH and FADH2.

The significance of NADH and FADH2 lies in their role as electron carriers that subsequently participate in the electron transport chain, leading to ATP production through oxidative phosphorylation. Therefore, the correct response highlights the specific molecules that undergo reduction (NAD and FAD) during these key biochemical processes.

In contrast, ATP and GTP are not reduced; instead, they are energy currency molecules produced in the cycle. CoA is involved in the formation of acetyl-CoA and is not a target for reduction, while citric acid (citrate) is an initial substrate formed in the cycle without being reduced. This understanding solid