Which molecule is converted to acetyl CoA during the Krebs cycle?

The conversion of pyruvate to acetyl CoA is a crucial step that occurs before the Krebs cycle, also known as the citric acid cycle or TCA cycle. This transformation happens in the mitochondria of the cell and is facilitated by the pyruvate dehydrogenase complex. Pyruvate is derived from glucose during glycolysis, which breaks down glucose into two molecules of pyruvate.

Once pyruvate enters the mitochondria, it undergoes decarboxylation, where one carbon atom is released as carbon dioxide (CO2). This process also involves the reduction of NAD+ to NADH, generating high-energy electron carriers that are integral to the electron transport chain. The remaining two-carbon molecule is then combined with coenzyme A (CoA) to form acetyl CoA.

Acetyl CoA serves as a substrate for the Krebs cycle, entering the cycle to produce further energy-rich molecules, such as NADH and FADH2, which drive ATP production through oxidative phosphorylation. Understanding this pivotal role of pyruvate in energy metabolism highlights the interconnectedness of cellular respiration processes.