FADH2

Definition

FADH2 is a redox-active coenzyme involved in the metabolism of carbohydrates, fats, and proteins, acting as an electron carrier in various biochemical reactions. It plays a critical role in cellular respiration by donating electrons to the electron transport chain, ultimately leading to the production of ATP. Understanding FADH2 is essential for grasping how energy is generated and transferred within cells, particularly during oxidative phosphorylation.

5 Must Know Facts For Your Next Test

1. FADH2 is produced during the Krebs Cycle and contributes to the electron transport chain by donating electrons at complex II, which is different from where NADH donates them.
2. The oxidation of one molecule of FADH2 results in the generation of approximately 1.5 ATP molecules, which is less than the 2.5 ATP generated from NADH.
3. FADH2 is derived from the flavin adenine dinucleotide (FAD) coenzyme, which accepts electrons and protons during redox reactions.
4. In addition to its role in oxidative phosphorylation, FADH2 also participates in fatty acid oxidation and the metabolism of certain amino acids.
5. FADH2 is a key player in aerobic respiration, and its levels can impact cellular energy production efficiency.

Review Questions

• How does FADH2 differ from NADH in terms of its role in cellular respiration?
  • FADH2 and NADH are both electron carriers in cellular respiration, but they differ in their donation points within the electron transport chain. FADH2 donates electrons at complex II, while NADH donates them at complex I. This difference results in varying ATP yields; specifically, oxidation of FADH2 generates around 1.5 ATP molecules compared to 2.5 ATP from NADH. These distinctions highlight the unique contributions each coenzyme makes to energy production.
• Explain how FADH2 contributes to the process of oxidative phosphorylation and its impact on ATP production.
  • FADH2 contributes to oxidative phosphorylation by donating electrons to complex II of the electron transport chain. This transfer initiates a series of redox reactions that pump protons across the mitochondrial membrane, creating a proton gradient. The energy from this gradient is harnessed by ATP synthase to produce ATP as protons flow back into the mitochondrial matrix. Thus, while FADH2 itself generates fewer ATP molecules than NADH, it still plays an essential role in overall ATP production during cellular respiration.
• Evaluate the significance of FADH2 in metabolic pathways and how alterations in its production could affect cellular energy metabolism.
  • FADH2 is significant as it not only contributes to ATP production through oxidative phosphorylation but also plays roles in various metabolic pathways, including fatty acid oxidation and amino acid metabolism. Alterations in FADH2 production can lead to energy imbalances within cells; for instance, insufficient levels may impair ATP generation, affecting cellular functions that require energy. Conversely, excessive production might indicate metabolic dysregulation. Overall, maintaining proper levels of FADH2 is crucial for efficient cellular energy metabolism.

Related terms

NADH:

NADH is another important coenzyme that carries electrons during metabolic processes, playing a similar role to FADH2 but with distinct pathways and energy yields.

Oxidative Phosphorylation: A process occurring in the mitochondria that utilizes the electron transport chain to create a proton gradient, ultimately driving ATP synthesis through ATP synthase.

Krebs Cycle:

A series of enzymatic reactions occurring in the mitochondrial matrix that generates FADH2 and NADH while oxidizing acetyl-CoA into carbon dioxide.