Question

9. In the electron transport chain picture above, how do electrons move from protein complex I to protein complex II? 1. I need you to remember that "Q" is ubiquinone which gets reduced at proteins l & I, and oxidized at protein III. "Reduced" means gains electrons, "oxidized" means loses electrons. 2. I need you to remember how "Q" moves from protein I to protein Do you remember? Don't overthink it, Preeda. As far as scientists know right now, the answer is one word. Starts with "d". Electron Transport Chain Intermembrane space H' ACyt c A IV 2e- FADH2 NADH H2O NAD+H Mitochondrial matrix Inner mitochondrial membrane

Answer 1

• Protein Complex I and II reduce Ubiquinone(Q) while complex III oxidizes it.
• PC I is made of Flavin mononucleotide and an Fe-S enzyme. It pumps 4H⁺across membrane i.e., it takes the ions from matrix and throws them out in intermembrane space.
• PC III is made up of Cyt b, Rieske center(has iron ion at its core), and Cyt c proteins (electron carriers). This complex is also named as cytochrome oxidoreductase. Oxidation states of Fe change from +2 to +3 as electrons pass through PC III.
• Q takes electrons from PC I and II and give them to III. Cyt c accepts the electrons. PC III does the further work of pumping these through membrane. Electrons get passes to Cyt c.This is how these electrons take part in ETC.