Oxidative phosphorylation

Definition

Oxidative phosphorylation is the metabolic process in which cells use energy derived from the electron transport chain to produce adenosine triphosphate (ATP) through the transfer of electrons. This process occurs in the inner mitochondrial membrane and is crucial for aerobic respiration, as it efficiently generates ATP by coupling electron transport to ATP synthesis, ultimately using oxygen as the final electron acceptor.

5 Must Know Facts For Your Next Test

1. Oxidative phosphorylation accounts for approximately 90% of ATP produced during cellular respiration, making it essential for energy metabolism in aerobic organisms.
2. The process relies on a proton motive force created by the pumping of protons into the intermembrane space of mitochondria, which drives ATP synthesis when protons flow back through ATP synthase.
3. Oxygen is critical in oxidative phosphorylation because it acts as the final electron acceptor in the electron transport chain, forming water when it combines with electrons and protons.
4. Dysfunctions in oxidative phosphorylation can lead to various metabolic disorders and are often linked to mitochondrial diseases.
5. In addition to mitochondria, chloroplasts also perform a similar process called photophosphorylation, which occurs during photosynthesis in plants and algae.

Review Questions

• How does oxidative phosphorylation connect with the processes of glycolysis and the citric acid cycle?
  • Oxidative phosphorylation is interconnected with glycolysis and the citric acid cycle through its reliance on reduced coenzymes produced during these pathways. Glycolysis breaks down glucose into pyruvate, generating NADH, which is then further oxidized in the citric acid cycle, producing additional NADH and FADH2. These reduced coenzymes carry high-energy electrons to the electron transport chain, where they contribute to oxidative phosphorylation, leading to ATP production.
• Discuss the role of oxygen in oxidative phosphorylation and why it is vital for aerobic organisms.
  • Oxygen plays a crucial role in oxidative phosphorylation as it serves as the final electron acceptor in the electron transport chain. This process involves a series of redox reactions where electrons are transferred along protein complexes, ultimately reaching oxygen, which combines with protons to form water. Without oxygen, the entire process would halt because electrons would back up along the chain, preventing ATP synthesis and leading to cellular energy failure. This makes oxygen essential for aerobic organisms that rely on efficient ATP production.
• Evaluate the implications of impaired oxidative phosphorylation on cellular function and overall health.
  • Impaired oxidative phosphorylation can lead to severe consequences for cellular function and overall health. When this process is disrupted, ATP production significantly declines, leading to energy deficits that can affect critical cellular activities such as muscle contraction, biosynthesis, and cell signaling. Furthermore, dysfunctional oxidative phosphorylation can result in an accumulation of reactive oxygen species (ROS), causing oxidative stress and damage to cellular components. This can contribute to various health issues, including neurodegenerative diseases, metabolic disorders, and even aging-related decline.

Related terms

Electron Transport Chain: A series of protein complexes located in the inner mitochondrial membrane that transfer electrons from electron donors to electron acceptors via redox reactions, leading to the creation of a proton gradient.

Chemiosmosis: The movement of ions across a selectively permeable membrane, down their electrochemical gradient, which in oxidative phosphorylation specifically refers to protons moving back into the mitochondrial matrix to drive ATP synthesis.

ATP Synthase: An enzyme complex that uses the proton gradient generated by the electron transport chain to catalyze the conversion of adenosine diphosphate (ADP) and inorganic phosphate into ATP.