Oxidative phosphorylation

Definition

Oxidative phosphorylation is the process by which cells generate ATP through the coupling of electron transport and the phosphorylation of ADP, primarily occurring in the mitochondria. This process utilizes the energy released from electrons as they move through a series of protein complexes in the electron transport chain, ultimately leading to the production of ATP. It is a vital step in cellular respiration, linking the breakdown of nutrients to energy production.

5 Must Know Facts For Your Next Test

1. Oxidative phosphorylation accounts for about 90% of ATP generated during cellular respiration, making it the most significant ATP-producing process.
2. The process requires oxygen as the final electron acceptor, which is essential for maintaining the flow of electrons through the electron transport chain.
3. Proton gradients created by electron transport are crucial for chemiosmosis, where protons flow back into the mitochondrial matrix through ATP synthase.
4. Each molecule of NADH can produce approximately 2.5 ATP, while each molecule of FADH2 produces about 1.5 ATP during oxidative phosphorylation.
5. Disruptions in oxidative phosphorylation can lead to decreased ATP production and have been linked to various diseases, including mitochondrial disorders.

Review Questions

• How does oxidative phosphorylation integrate with glycolysis and the citric acid cycle to enhance ATP production?
  • Oxidative phosphorylation is closely linked to glycolysis and the citric acid cycle, as both processes produce reduced coenzymes (NADH and FADH2) that feed electrons into the electron transport chain. Glycolysis occurs in the cytoplasm and breaks down glucose into pyruvate, generating NADH, while the citric acid cycle occurs in the mitochondria, further oxidizing pyruvate and producing both NADH and FADH2. These high-energy electrons are then transferred to the electron transport chain, leading to ATP synthesis via oxidative phosphorylation.
• Discuss how proton gradients created during oxidative phosphorylation contribute to ATP synthesis.
  • During oxidative phosphorylation, electrons are passed along protein complexes in the electron transport chain, releasing energy that is used to pump protons from the mitochondrial matrix into the intermembrane space. This creates a proton gradient across the inner mitochondrial membrane, which has a higher concentration of protons outside than inside. The flow of protons back into the matrix through ATP synthase harnesses this gradient's energy to convert ADP and inorganic phosphate into ATP, making chemiosmosis a critical component of ATP synthesis.
• Evaluate the importance of oxidative phosphorylation in cellular metabolism and its implications for human health.
  • Oxidative phosphorylation plays a pivotal role in cellular metabolism by producing the majority of ATP required for various biological functions. Its efficiency directly influences energy availability for processes like muscle contraction, nerve impulse transmission, and biosynthesis. Disruptions or inefficiencies in oxidative phosphorylation can lead to a range of health issues, including metabolic disorders and neurodegenerative diseases. Understanding this process also sheds light on potential therapeutic targets for diseases linked to mitochondrial dysfunction.

Related terms

Electron transport chain: A series of protein complexes and other molecules located in the inner mitochondrial membrane that transfer electrons from electron donors to electron acceptors, ultimately driving the synthesis of ATP.

Chemiosmosis: The movement of ions across a selectively permeable membrane, which in oxidative phosphorylation refers specifically to protons moving through ATP synthase to drive ATP production.

ATP synthase: An enzyme that catalyzes the formation of ATP from ADP and inorganic phosphate, powered by the flow of protons down their concentration gradient across the inner mitochondrial membrane.