The redox reaction involving FADH2 entering the electron transport chain (ETC) by reacting with cytochrome c is a crucial step in cellular respiration. This process takes place during the final stage of respiration, which is oxidative phosphorylation, occurring within the inner mitochondrial membrane. Here's a simplified overview of the reaction:
1. **FADH2:** FADH2, or flavin adenine dinucleotide in its reduced form, carries high-energy electrons derived from previous stages of cellular respiration, such as the citric acid cycle (Krebs cycle).
2. **Cytochrome c:** Cytochrome c is a protein located within the inner mitochondrial membrane. It serves as an electron carrier, shuttling electrons between different protein complexes of the ETC.
3. **Redox Reaction:** FADH2 donates its high-energy electrons to cytochrome c in a redox reaction. This donation involves the transfer of electrons from FADH2 to cytochrome c.
4. **Energy Transfer:** As electrons move from FADH2 to cytochrome c, energy is released. This energy is used to pump protons (H+ ions) across the inner mitochondrial membrane, creating an electrochemical gradient.
5. **Role in ATP Synthesis:** The proton gradient established during the ETC is essential for the enzyme ATP synthase to generate ATP. Protons flow back into the mitochondrial matrix through ATP synthase, driving the phosphorylation of ADP to ATP.
In summary, the redox reaction between FADH2 and cytochrome c in the electron transport chain is a critical step in harnessing the energy from electrons to produce ATP, the cell's primary energy currency. This process demonstrates the conversion of chemical energy (in FADH2) into proton gradient energy, ultimately leading to ATP synthesis.