Oxidative phosphorylation

Definition

Oxidative phosphorylation is the process by which cells generate ATP through the electron transport chain and chemiosmosis, occurring in the mitochondria. This crucial metabolic pathway utilizes electrons from reduced coenzymes generated in earlier stages of cellular respiration, such as glycolysis and the citric acid cycle, to drive ATP synthesis, linking energy metabolism to cellular functions.

5 Must Know Facts For Your Next Test

1. Oxidative phosphorylation is responsible for producing about 90% of the ATP generated during cellular respiration.
2. The process begins when electrons are transferred through the electron transport chain, leading to the pumping of protons from the mitochondrial matrix into the intermembrane space.
3. The resulting proton gradient creates potential energy that is used by ATP synthase to convert ADP and inorganic phosphate into ATP.
4. Oxygen serves as the final electron acceptor in this process, forming water as a byproduct when it combines with electrons and protons.
5. Disruptions in oxidative phosphorylation can lead to reduced ATP production and are associated with various metabolic disorders and diseases.

Review Questions

• How does oxidative phosphorylation relate to glycolysis and the citric acid cycle in energy production?
  • Oxidative phosphorylation relies on the reduced coenzymes, NADH and FADH2, generated during glycolysis and the citric acid cycle. These coenzymes donate electrons to the electron transport chain, which initiates the series of reactions leading to ATP production. Thus, while glycolysis breaks down glucose and the citric acid cycle further oxidizes products from glycolysis, oxidative phosphorylation serves as the final stage of cellular respiration where most ATP is produced.
• Discuss the role of the electron transport chain in oxidative phosphorylation and its importance for cellular metabolism.
  • The electron transport chain is critical for oxidative phosphorylation as it facilitates the transfer of electrons from NADH and FADH2 to molecular oxygen. This transfer releases energy that is used to pump protons across the inner mitochondrial membrane, creating a proton gradient. This gradient not only drives ATP synthesis via ATP synthase but also maintains metabolic balance by regenerating NAD+ and FAD, which are essential for glycolysis and the citric acid cycle.
• Evaluate how disruptions in oxidative phosphorylation can affect overall cellular function and health.
  • Disruptions in oxidative phosphorylation can severely impact cellular function by decreasing ATP production, leading to energy deficits in cells. Such disruptions can stem from genetic mutations, toxins, or lack of oxygen, contributing to various health issues like neurodegenerative diseases and metabolic disorders. Since ATP is vital for many cellular processes including muscle contraction, biosynthesis, and cell signaling, a decline in its production can result in widespread dysfunction across tissues and organ systems.

Related terms

Electron Transport Chain: A series of protein complexes located in the inner mitochondrial membrane that transfer electrons from NADH and FADH2 to oxygen, creating a proton gradient.

ATP Synthase: An enzyme that uses the proton gradient created by the electron transport chain to synthesize ATP from ADP and inorganic phosphate during chemiosmosis.

Chemiosmosis: The movement of protons across a membrane down their concentration gradient, which generates energy for ATP synthesis in oxidative phosphorylation.