Complex I of the electron transport chain accepts electrons from _____ A. Cyt c B. NADH C. CoQ D. ATP E. FADH2

The correct answer is B. NADH.

Explanation:

Complex I of the electron transport chain, also known as NADH:ubiquinone oxidoreductase, is primarily responsible for accepting electrons from NADH. It catalyzes the transfer of electrons from NADH to coenzyme Q (CoQ or ubiquinone), which is then reduced to ubiquinol. This process is coupled with the translocation of protons from the mitochondrial matrix to the intermembrane space, contributing to the establishment of the proton gradient used for ATP synthesis. Although FADH2 interacts with the electron transport chain, it does so through Complex II, not Complex I.