Oxidative phosphorylation

Definition

Oxidative phosphorylation is a metabolic process that occurs in the mitochondria of cells, where ATP (adenosine triphosphate) is produced using energy derived from the electron transport chain and the reduction of oxygen. This process is essential for cellular respiration, as it allows cells to convert energy stored in nutrients into a usable form, facilitating numerous biological functions.

5 Must Know Facts For Your Next Test

1. Oxidative phosphorylation produces about 28 to 30 molecules of ATP per glucose molecule, making it a highly efficient way for cells to generate energy.
2. The process relies on a proton gradient created by the movement of electrons through the electron transport chain, which drives protons into the intermembrane space.
3. Oxygen serves as the final electron acceptor in oxidative phosphorylation, forming water when it combines with electrons and protons at the end of the electron transport chain.
4. Inhibitors like cyanide can block oxidative phosphorylation by interfering with electron transport, leading to reduced ATP production and cellular respiration failure.
5. Oxidative phosphorylation is tightly regulated and can be influenced by factors such as substrate availability, oxygen levels, and cellular energy needs.

Review Questions

• How does oxidative phosphorylation contribute to cellular respiration and energy production in cells?
  • Oxidative phosphorylation is a crucial part of cellular respiration that occurs after glycolysis and the citric acid cycle. It uses the electrons generated from these previous processes, transferring them through the electron transport chain located in the mitochondria. This transfer creates a proton gradient across the inner mitochondrial membrane, which drives ATP synthesis through ATP synthase. Thus, it transforms energy from nutrients into ATP, enabling essential cellular functions.
• Discuss the role of oxygen in oxidative phosphorylation and what happens if oxygen levels are low.
  • Oxygen acts as the final electron acceptor in oxidative phosphorylation, allowing electrons to flow through the electron transport chain until they combine with protons and oxygen to form water. If oxygen levels are low, this process halts because there are no available electrons to accept, resulting in decreased ATP production. Cells may switch to anaerobic respiration or fermentation to generate some ATP, but this is far less efficient than oxidative phosphorylation.
• Evaluate how inhibitors of oxidative phosphorylation affect overall cellular metabolism and health.
  • Inhibitors of oxidative phosphorylation disrupt the electron transport chain and prevent ATP production, leading to energy depletion in cells. For example, substances like cyanide bind to cytochrome c oxidase in the electron transport chain, stopping electron flow and halting ATP synthesis. This can result in severe metabolic dysfunction and cell death if not mitigated quickly. Understanding these inhibitors helps illustrate the critical nature of oxidative phosphorylation for maintaining cellular health and function.

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, generating a proton gradient.

Chemiosmosis: The movement of protons across a membrane, specifically during oxidative phosphorylation, which drives the synthesis of ATP through ATP synthase.

ATP Synthase:

An enzyme that synthesizes ATP from ADP and inorganic phosphate, utilizing the energy from the proton gradient established by the electron transport chain.