Final answer:
For every 2 electrons moved from ubiquinol to cytochrome c, 4 H+ are moved. Ubiquinone is the compound that receives electrons from NADH. Ubiquinone and cytochrome c are mobile electron carriers in the electron transport chain that differ from the other complex protein components.
Step-by-step explanation:
For every 2 electrons moved from ubiquinol to cytochrome c (cyt c), 4 protons (H+) are moved in the process. This happens because complex III of the electron transport chain pumps protons into the intermembrane space as it transfers the electrons. Complex III passes on electrons from coenzyme-Q (QH₂) to cytochrome c, and for each ubiquinol molecule (QH₂) oxidized, 4 protons are pumped.
The compound that receives electrons from NADH is ubiquinone. Ubiquinone plays a crucial role by accepting electrons from complexes I and II and passing them on to complex III. The movement of electrons through these complexes is associated with the movement of hydrogen ions across a mitochondrial membrane, which is essential for creating the proton gradient used by ATP synthase to produce ATP.
As for the roles of ubiquinone and cytochrome c in the electron transport chain, they are both mobile electron carriers. However, ubiquinone carries electrons between complex I and III or between complex II and III, whereas cytochrome c transfers electrons from complex III to complex IV. Thus, ubiquinone and cytochrome c differ from the other components of the electron transport chain which are protein complexes embedded in the mitochondrial membrane.