Electron transport chain

Definition

The electron transport chain (ETC) is a series of protein complexes and other molecules located in the inner mitochondrial membrane that play a crucial role in cellular respiration. It transfers electrons from electron donors like NADH and FADH2 to electron acceptors through redox reactions, ultimately helping produce ATP, the main energy currency of cells. This process also involves the pumping of protons across the membrane, creating a proton gradient that drives ATP synthesis via chemiosmosis.

5 Must Know Facts For Your Next Test

1. The electron transport chain consists of four main protein complexes (Complex I to IV) and mobile electron carriers such as ubiquinone and cytochrome c.
2. Oxygen is the final electron acceptor in the electron transport chain, combining with protons to form water, which is essential for maintaining the flow of electrons.
3. As electrons are transferred along the chain, energy released is used to pump protons from the mitochondrial matrix into the intermembrane space, creating an electrochemical gradient.
4. This proton gradient generates potential energy, which ATP synthase harnesses to produce ATP during oxidative phosphorylation.
5. Disruptions in the electron transport chain can lead to decreased ATP production and increased production of reactive oxygen species, contributing to various diseases.

Review Questions

• How does the electron transport chain contribute to ATP production in cells?
  • The electron transport chain contributes to ATP production by transferring electrons from NADH and FADH2 through a series of protein complexes. As electrons move along the chain, they release energy that pumps protons into the intermembrane space, creating a proton gradient. This gradient is then utilized by ATP synthase to convert ADP and inorganic phosphate into ATP during oxidative phosphorylation.
• What role does oxygen play in the function of the electron transport chain?
  • Oxygen plays a vital role as the final electron acceptor in the electron transport chain. At the end of the chain, oxygen combines with electrons and protons to form water. This process is essential for maintaining continuous flow through the ETC, as it prevents a backup of electrons, ensuring efficient ATP production during cellular respiration.
• Evaluate how disruptions in the electron transport chain can affect cellular metabolism and overall cell health.
  • Disruptions in the electron transport chain can significantly impair cellular metabolism by reducing ATP production, which is crucial for numerous cellular functions. A decrease in ATP levels can lead to insufficient energy for processes such as muscle contraction, neurotransmission, and biosynthesis. Additionally, impaired ETC function often results in increased production of reactive oxygen species, which can cause oxidative stress and damage cellular components, ultimately contributing to various diseases and metabolic disorders.

Related terms

ATP synthase: An enzyme complex that uses the proton gradient generated by the electron transport chain to synthesize ATP from ADP and inorganic phosphate.

oxidative phosphorylation: The metabolic pathway where ATP is formed as a result of the transfer of electrons from NADH and FADH2 through the electron transport chain, coupled with the reduction of oxygen to water.

chemiosmosis: The movement of ions across a selectively permeable membrane down their electrochemical gradient, which is crucial for ATP production in mitochondria during cellular respiration.