Fadh2

Definition

FADH2 is a reduced form of flavin adenine dinucleotide, an important coenzyme that plays a critical role in cellular respiration and metabolism by acting as an electron carrier. It is produced during metabolic processes like the Krebs cycle and fatty acid oxidation, transferring electrons to the electron transport chain to help generate ATP, the energy currency of the cell.

5 Must Know Facts For Your Next Test

1. FADH2 is generated during the Krebs cycle when succinate is converted to fumarate by the enzyme succinate dehydrogenase.
2. Each molecule of FADH2 contributes approximately 1.5 ATP during oxidative phosphorylation, compared to 2.5 ATP contributed by NADH.
3. FADH2 enters the electron transport chain at complex II (succinate dehydrogenase), bypassing complex I, which results in fewer protons being pumped across the mitochondrial membrane.
4. FADH2 can also be produced during the beta-oxidation of fatty acids, which breaks down fats for energy.
5. The regeneration of FAD from FADH2 occurs during various metabolic reactions, ensuring a continuous supply of this coenzyme for ongoing cellular processes.

Review Questions

• How does FADH2 contribute to ATP production in cellular respiration, and what is its role in the Krebs cycle?
  • FADH2 plays a crucial role in ATP production by serving as an electron carrier in cellular respiration. During the Krebs cycle, it is produced when succinate is converted into fumarate. FADH2 then donates electrons to the electron transport chain at complex II, leading to proton pumping and ultimately ATP synthesis through oxidative phosphorylation. This process highlights FADH2's integral role in converting metabolic energy into a usable form for the cell.
• Compare the contributions of FADH2 and NADH to ATP synthesis and explain why their roles differ.
  • FADH2 and NADH both act as electron carriers in cellular respiration but contribute differently to ATP synthesis. Each molecule of FADH2 generates about 1.5 ATP, while NADH generates about 2.5 ATP. This difference arises because FADH2 donates its electrons at complex II of the electron transport chain, resulting in fewer protons being pumped across the membrane compared to NADH, which donates at complex I. Therefore, the entry point into the chain significantly affects their respective contributions to ATP production.
• Evaluate the importance of FADH2 in energy metabolism and discuss how disruptions in its production can affect cellular function.
  • FADH2 is vital for energy metabolism as it facilitates electron transfer within the electron transport chain, contributing to ATP generation. Disruptions in its production, such as those caused by defects in enzymes involved in the Krebs cycle or fatty acid oxidation, can lead to decreased energy availability for cellular functions. This can result in various metabolic disorders or energy deficiencies, emphasizing how essential FADH2 is for maintaining cellular health and function.

Related terms

NADH:

NADH is another key electron carrier in cellular respiration, similar to FADH2, but it is derived from nicotinamide adenine dinucleotide and typically contributes more to ATP production per molecule.

Krebs Cycle:

The Krebs cycle, also known as the citric acid cycle, is a series of enzymatic reactions that produce FADH2 and NADH while oxidizing acetyl-CoA to CO2.

Electron Transport Chain: The electron transport chain is a series of protein complexes in the inner mitochondrial membrane where FADH2 and NADH donate electrons, leading to the production of ATP through oxidative phosphorylation.