Oxidative Decarboxylation

Definition

Oxidative decarboxylation is a biochemical process in which a carboxyl group is removed from a molecule as carbon dioxide (CO₂), coupled with the reduction of an electron carrier, typically NAD⁺ to NADH. This process plays a crucial role in cellular respiration, specifically linking glycolysis and the citric acid cycle by converting pyruvate into acetyl-CoA, thus facilitating the entry of carbon compounds into the citric acid cycle for energy production.

5 Must Know Facts For Your Next Test

1. Oxidative decarboxylation occurs in the mitochondria, where pyruvate is transported after glycolysis.
2. The enzyme complex responsible for this reaction is known as the pyruvate dehydrogenase complex (PDC).
3. During this reaction, one molecule of CO₂ is released for each pyruvate molecule processed.
4. The conversion of pyruvate to acetyl-CoA through oxidative decarboxylation is a critical regulatory step that links glycolysis to the citric acid cycle.
5. This process not only produces acetyl-CoA but also generates NADH, which is used in the electron transport chain for ATP production.

Review Questions

• How does oxidative decarboxylation connect glycolysis to the citric acid cycle?
  • Oxidative decarboxylation serves as a vital link between glycolysis and the citric acid cycle by converting pyruvate, the end product of glycolysis, into acetyl-CoA. This transformation occurs in the mitochondria, where pyruvate loses a carboxyl group as CO₂ and reduces NAD⁺ to NADH. The resulting acetyl-CoA then enters the citric acid cycle, allowing for further oxidation and energy extraction from carbohydrates.
• Discuss the role of the pyruvate dehydrogenase complex in oxidative decarboxylation and its significance in energy metabolism.
  • The pyruvate dehydrogenase complex (PDC) is an essential multi-enzyme complex that catalyzes oxidative decarboxylation. It facilitates the conversion of pyruvate to acetyl-CoA while releasing CO₂ and generating NADH. This reaction is significant because it effectively links carbohydrate metabolism to the citric acid cycle, allowing for efficient energy production through the subsequent oxidation of acetyl-CoA and the generation of ATP in aerobic respiration.
• Evaluate how oxidative decarboxylation influences overall cellular respiration and energy yield.
  • Oxidative decarboxylation significantly impacts cellular respiration by determining how efficiently cells can utilize glucose for energy. By converting pyruvate into acetyl-CoA, it enables entry into the citric acid cycle where further oxidation takes place. This step not only generates high-energy carriers like NADH but also prepares substrates for ATP synthesis in oxidative phosphorylation. Therefore, any disruption in this process can lead to decreased energy yield and affect overall metabolic efficiency.

Related terms

Pyruvate: A key intermediate in cellular metabolism formed from glucose during glycolysis, which can be converted into acetyl-CoA through oxidative decarboxylation.

Citric Acid Cycle: A series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.

NAD⁺: Nicotinamide adenine dinucleotide, a coenzyme that acts as an electron carrier in many metabolic processes, including oxidative decarboxylation and the citric acid cycle.