Where are the electrons passed onto FAD from succinate dehydrogenase sent to?

The electrons passed onto FAD from succinate dehydrogenase are indeed sent to coenzyme Q, also known as ubiquinone. Succinate dehydrogenase plays a crucial role in both the citric acid cycle and the electron transport chain. It catalyzes the conversion of succinate to fumarate, during which FAD is reduced to FADH2 as it accepts the electrons from succinate.

Once FADH2 is formed, its electrons are transferred to coenzyme Q. Coenzyme Q acts as a key electron carrier in the electron transport chain, where it accepts electrons and subsequently donates them to complex III (cytochrome bc1 complex). This process is essential for cellular respiration, as it contributes to the generation of a proton gradient used to produce ATP via ATP synthase.

Therefore, the electrons originated from succinate during the citric acid cycle ultimately enter a pathway that results in ATP production through oxidative phosphorylation. This connection between the citric acid cycle and the electron transport chain highlights the integrated nature of cellular metabolism.