Final answer:
FADH2 is an essential high-energy molecule in cellular respiration that donates electrons to the electron transport chain in the mitochondria, facilitating the production of ATP, the cell's main energy source.
Step-by-step explanation:
The function of FADH2 (flavin adenine dinucleotide) in cellular respiration is crucial, especially during the electron transport chain stage. FADH2 is a high-energy molecule created during the Krebs cycle, also known as the citric acid cycle. During this cycle, succinate dehydrogenase catalyzes the conversion of succinate to fumarate, in which FAD is reduced to FADH2. This molecule carries electrons to the electron transport chain within the inner mitochondrial membrane, where it donates electrons to the chain. The energy released by these electrons is then used to pump protons into the intermembrane space, creating a proton gradient. By flowing through ATP synthase, these protons facilitate the synthesis of ATP.
FADH2 directly enters the electron transport chain at a lower energy level compared to NADH, producing fewer ATP molecules. Still, its role is vital as it contributes to the overall production of ATP, which is the primary energy currency of the cell. The process concludes with the regeneration of FAD, a continuous cycle allowing for ongoing glucose metabolism and energy production.