NADH dehydrogenase

Definition

NADH dehydrogenase is an enzyme that plays a crucial role in the electron transport chain by facilitating the transfer of electrons from NADH to ubiquinone (coenzyme Q). This process not only helps in regenerating NAD+ for glycolysis and the citric acid cycle but also contributes to the creation of a proton gradient across the inner mitochondrial membrane, which is essential for ATP synthesis during oxidative phosphorylation.

5 Must Know Facts For Your Next Test

1. NADH dehydrogenase is also referred to as Complex I of the electron transport chain.
2. The enzyme catalyzes the reduction of ubiquinone to ubiquinol while oxidizing NADH to NAD+.
3. As electrons are transferred through NADH dehydrogenase, protons (H+) are pumped from the mitochondrial matrix into the intermembrane space, contributing to the proton gradient.
4. The activity of NADH dehydrogenase is vital for cellular respiration, as it influences both energy production and metabolic balance.
5. Defects in NADH dehydrogenase can lead to various mitochondrial diseases due to impaired ATP production.

Review Questions

• How does NADH dehydrogenase contribute to the overall process of oxidative phosphorylation?
  • NADH dehydrogenase contributes to oxidative phosphorylation by transferring electrons from NADH to ubiquinone, which is part of the electron transport chain. This transfer not only regenerates NAD+, allowing glycolysis and the citric acid cycle to continue but also drives the pumping of protons into the intermembrane space. This creates a proton gradient that is crucial for ATP synthesis via ATP synthase, making it a key player in cellular energy production.
• Discuss the role of NADH dehydrogenase in maintaining the balance of metabolites within the mitochondria.
  • NADH dehydrogenase helps maintain metabolic balance within mitochondria by regulating the levels of NAD+ and NADH. By converting NADH back to NAD+, it ensures that there is sufficient NAD+ available for various metabolic reactions, including glycolysis and the citric acid cycle. This balance is essential for efficient energy production and preventing metabolic bottlenecks that could hinder cellular function.
• Evaluate the impact of dysfunctional NADH dehydrogenase on cellular respiration and potential health implications.
  • Dysfunctional NADH dehydrogenase severely impacts cellular respiration by disrupting the electron transport chain's functionality. If this enzyme does not operate effectively, less ATP will be produced due to a reduced proton gradient, leading to lower energy availability for cellular processes. This impairment can result in various mitochondrial diseases, characterized by symptoms such as muscle weakness and neurological issues, highlighting the enzyme's critical role in health.

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 ATP production.

Oxidative Phosphorylation: The metabolic pathway through which cells use enzymes to oxidize nutrients, thereby releasing energy, which is used to produce ATP from ADP and inorganic phosphate.

Ubiquinone:

Also known as coenzyme Q, it is a lipid-soluble molecule that serves as an electron carrier between NADH dehydrogenase and the next complex in the electron transport chain.