Pyruvate Oxidation: Videos & Practice Problems

Pyruvate oxidation is the second step of cellular respiration, following glycolysis. It occurs in the mitochondrial matrix. During this process, each pyruvate molecule produced from glycolysis is converted into Acetyl CoA. This conversion also results in the production of NADH and CO₂. Specifically, pyruvate loses electrons (is oxidized), which are accepted by NAD⁺ to form NADH. Each pyruvate, containing three carbon atoms, loses one carbon as CO₂, while the remaining carbons attach to CoA to form Acetyl CoA. The Acetyl CoA then enters the Krebs cycle for further energy extraction.

Pyruvate oxidation produces three main products per glucose molecule: 2 Acetyl CoA, 2 NADH, and 2 CO₂. Each pyruvate molecule, containing three carbon atoms, loses one carbon as CO₂, while the remaining two carbons attach to CoA to form Acetyl CoA. Additionally, during the oxidation process, electrons are transferred to NAD⁺, forming NADH. These products are crucial for the continuation of cellular respiration, as Acetyl CoA enters the Krebs cycle, and NADH is used in the electron transport chain to generate ATP.

Pyruvate oxidation is a critical step in cellular respiration as it bridges glycolysis and the Krebs cycle. By converting pyruvate into Acetyl CoA, it prepares the substrate for the Krebs cycle, where further energy extraction occurs. Additionally, the process produces NADH, which carries high-energy electrons to the electron transport chain, contributing to ATP production. The CO₂ released during pyruvate oxidation is a waste product that is expelled from the cell. Overall, pyruvate oxidation ensures the efficient continuation of cellular respiration, maximizing energy extraction from glucose.

NADH production during pyruvate oxidation is crucial because NADH serves as an electron carrier in cellular respiration. When pyruvate is oxidized, it loses electrons, which are accepted by NAD⁺, forming NADH. These high-energy electrons carried by NADH are later used in the electron transport chain to generate ATP, the cell's primary energy currency. Without the production of NADH, the electron transport chain would lack the necessary electrons to drive ATP synthesis, significantly reducing the cell's energy production efficiency.

The Acetyl CoA produced in pyruvate oxidation enters the Krebs cycle, also known as the citric acid cycle. In the Krebs cycle, Acetyl CoA combines with oxaloacetate to form citrate, which undergoes a series of enzymatic reactions. These reactions result in the production of ATP, NADH, and FADH₂, as well as the release of CO₂. The NADH and FADH₂ produced carry high-energy electrons to the electron transport chain, where they are used to generate additional ATP. Thus, Acetyl CoA is essential for the continuation of cellular respiration and energy production.