Oxidative decarboxylation

Definition

Oxidative decarboxylation is a biochemical process in which a carboxyl group is removed from a molecule, releasing carbon dioxide and transferring electrons to an electron carrier. This reaction is crucial in cellular respiration as it links glycolysis to the citric acid cycle by converting pyruvate into acetyl-CoA, which then enters the cycle for further energy extraction.

5 Must Know Facts For Your Next Test

1. Oxidative decarboxylation occurs in the mitochondria of eukaryotic cells, specifically within the mitochondrial matrix.
2. The enzyme complex known as the pyruvate dehydrogenase complex catalyzes the oxidative decarboxylation of pyruvate.
3. During this process, one molecule of NAD+ is reduced to NADH, capturing high-energy electrons for later use in the electron transport chain.
4. In addition to producing acetyl-CoA, oxidative decarboxylation is a critical regulatory step that helps control the flow of carbon into the citric acid cycle.
5. The release of carbon dioxide during oxidative decarboxylation contributes to the overall carbon loss in aerobic respiration, highlighting its role in energy metabolism.

Review Questions

• How does oxidative decarboxylation connect glycolysis and the citric acid cycle?
  • Oxidative decarboxylation serves as a bridge between glycolysis and the citric acid cycle by converting pyruvate, the end product of glycolysis, into acetyl-CoA. This conversion occurs in the mitochondria and involves removing a carboxyl group from pyruvate, resulting in the release of carbon dioxide. Acetyl-CoA then enters the citric acid cycle, allowing the energy stored in glucose to be fully harnessed through subsequent reactions.
• Discuss the role of the pyruvate dehydrogenase complex in oxidative decarboxylation and its significance in cellular respiration.
  • The pyruvate dehydrogenase complex is a critical enzyme that catalyzes oxidative decarboxylation by facilitating the conversion of pyruvate to acetyl-CoA. It operates through a multi-step process involving several cofactors, which ensures efficient conversion while capturing energy in the form of NADH. The significance of this complex lies in its regulatory function; it helps coordinate metabolic pathways by controlling how much pyruvate enters the citric acid cycle, thereby influencing overall energy production within the cell.
• Evaluate the importance of oxidative decarboxylation in maintaining cellular energy homeostasis and its implications for metabolic diseases.
  • Oxidative decarboxylation is essential for maintaining cellular energy homeostasis as it ensures that pyruvate generated from glucose metabolism can be efficiently converted into acetyl-CoA for entry into the citric acid cycle. Disruptions in this process can lead to an accumulation of pyruvate and a decrease in ATP production, impacting overall cellular function. In metabolic diseases such as diabetes or certain mitochondrial disorders, impaired oxidative decarboxylation can exacerbate energy deficits and contribute to complications associated with altered glucose metabolism and increased reliance on alternative pathways for energy production.

Related terms

Pyruvate: A key intermediate in metabolism formed from glucose during glycolysis, which undergoes oxidative decarboxylation to produce acetyl-CoA.

Acetyl-CoA:

A central metabolic molecule that is produced from pyruvate and is essential for entering the citric acid cycle.

Citric Acid Cycle: A series of enzymatic reactions that further oxidize acetyl-CoA to produce energy-rich molecules such as NADH and FADH2.