Fadh2

Definition

FADH2 is a reduced coenzyme derived from riboflavin that plays a crucial role in the metabolism of carbohydrates, fatty acids, and amino acids. It acts as an electron carrier in cellular respiration, specifically in the electron transport chain, contributing to the production of ATP through oxidative phosphorylation.

5 Must Know Facts For Your Next Test

1. FADH2 is generated during the citric acid cycle when succinate is converted to fumarate through the action of succinate dehydrogenase.
2. Each molecule of FADH2 can contribute to the synthesis of approximately 1.5 ATP molecules during oxidative phosphorylation, which is less than what NADH contributes.
3. FADH2 donates its electrons to Complex II of the electron transport chain, bypassing Complex I, which differentiates its energy yield compared to NADH.
4. The conversion of FAD to FADH2 involves a redox reaction where FAD gains two electrons and two protons, making it a key player in cellular respiration.
5. In addition to its role in energy production, FADH2 is also involved in various biosynthetic pathways and redox reactions within the cell.

Review Questions

• How does FADH2 contribute to ATP production in the electron transport chain?
  • FADH2 contributes to ATP production by donating electrons to Complex II of the electron transport chain. This process allows for the transfer of electrons through a series of protein complexes, ultimately leading to the pumping of protons across the inner mitochondrial membrane. The resulting proton gradient powers ATP synthase, which synthesizes ATP from ADP and inorganic phosphate. The donation of electrons from FADH2 is crucial for maintaining the flow of electrons necessary for efficient ATP production.
• Discuss the differences between FADH2 and NADH in terms of their roles in cellular respiration and energy yield.
  • FADH2 and NADH both serve as electron carriers in cellular respiration, but they differ in their points of entry into the electron transport chain and energy yield. While NADH donates electrons to Complex I, resulting in the pumping of protons through multiple complexes, FADH2 donates electrons directly to Complex II, bypassing Complex I. This results in a lower energy yield for FADH2, generating approximately 1.5 ATP compared to 2.5 ATP from each NADH molecule. This difference highlights their distinct roles in metabolic pathways.
• Evaluate the importance of FADH2 in metabolism beyond its role in ATP synthesis.
  • FADH2 is important not only for ATP synthesis but also for various metabolic processes within cells. It plays a key role in redox reactions, facilitating the conversion of substrates during fatty acid oxidation and certain amino acid metabolism. Furthermore, FADH2 is involved in biosynthetic pathways where reducing power is needed for anabolic reactions. By participating in these diverse metabolic functions, FADH2 supports both energy production and cellular biosynthesis, making it a vital coenzyme for overall metabolic health.

Related terms

FAD: Flavin adenine dinucleotide, the oxidized form of FADH2 that accepts electrons during metabolic reactions.

Electron Transport Chain: A series of protein complexes and other molecules located in the inner mitochondrial membrane that transfer electrons from electron donors like FADH2 and NADH to electron acceptors, ultimately generating ATP.

ATP Synthase: An enzyme complex that utilizes the proton gradient established by the electron transport chain to synthesize ATP from ADP and inorganic phosphate.