FADH2

Definition

FADH2 is a reduced form of flavin adenine dinucleotide, a crucial electron carrier in cellular respiration. It plays a key role in transferring electrons from metabolic substrates to the electron transport chain, contributing to ATP production through oxidative phosphorylation. This process is integral for energy metabolism, linking the breakdown of carbohydrates, proteins, and lipids to energy generation.

5 Must Know Facts For Your Next Test

1. FADH2 is generated during the Citric Acid Cycle when succinate is converted to fumarate, highlighting its role in energy production.
2. For each molecule of FADH2 oxidized in the electron transport chain, approximately 1.5 ATP molecules are produced, which is less than the 2.5 ATP produced by NADH.
3. FADH2 donates its electrons to Complex II of the electron transport chain, bypassing Complex I, which makes its ATP yield lower compared to NADH.
4. The recycling of FADH2 back to FAD is essential for maintaining metabolic pathways, ensuring a continuous supply of energy in cells.
5. FADH2 is not only involved in cellular respiration but also plays roles in various metabolic pathways, including fatty acid oxidation and amino acid metabolism.

Review Questions

• How does FADH2 contribute to the overall energy production during cellular respiration?
  • FADH2 contributes to energy production by acting as an electron carrier that transports electrons to the electron transport chain. When FADH2 donates its electrons at Complex II, it facilitates the production of ATP through oxidative phosphorylation. Although it generates less ATP compared to NADH due to its entry point in the electron transport chain, it remains vital for efficient energy metabolism and helps power various cellular processes.
• Compare and contrast the roles of FADH2 and NADH in cellular respiration.
  • FADH2 and NADH are both crucial electron carriers in cellular respiration that transfer high-energy electrons to the electron transport chain. However, they differ in their ATP yield; FADH2 produces about 1.5 ATP molecules while NADH produces around 2.5 ATP molecules. This difference arises because FADH2 enters the electron transport chain at Complex II, bypassing Complex I where NADH enters. This positioning impacts their overall contributions to ATP synthesis.
• Evaluate the significance of FADH2 in linking different metabolic pathways and its impact on cellular energy balance.
  • FADH2 plays a significant role in linking various metabolic pathways such as carbohydrate metabolism, fatty acid oxidation, and amino acid catabolism. By participating in these pathways and supplying electrons for ATP production through oxidative phosphorylation, it helps maintain a balanced cellular energy state. The ability of FADH2 to act as an intermediary between different substrates allows cells to efficiently utilize available nutrients for energy, thus ensuring optimal functioning under varying metabolic demands.

Related terms

NADH:

NADH is another important electron carrier in cellular respiration, similar to FADH2, but it is derived from nicotinamide adenine dinucleotide and generally produces more ATP when oxidized.

Citric Acid Cycle: The Citric Acid Cycle is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate derived from carbohydrates, fats, and proteins.

Electron Transport Chain: The Electron Transport Chain is a series of protein complexes located in the inner mitochondrial membrane that facilitate the transfer of electrons from NADH and FADH2 to oxygen, ultimately generating ATP.