Chp 19 ETC Flashcards
What are the starting materials of the electron transport chain (ETC)?
NADH, FADH2, O2, ADP, and Pi.
What are the end products of the electron transport chain (ETC)?
ATP, H2O, NAD+, and FAD.
Which enzyme complexes are involved in the ETC?
Complex I (NADH dehydrogenase), Complex II (succinate dehydrogenase), Complex III (cytochrome bc1 complex), Complex IV (cytochrome c oxidase), and ATP synthase.
Which pathway produces the most ATP molecules?
The electron transport chain produces the most ATP molecules (around 26-28 ATP).
What is the role of NADH in the ETC?
NADH donates two high-energy electrons to Complex I.
What is the role of FADH2 in the ETC?
FADH2 donates electrons to Complex II, which are then transferred to coenzyme Q.
What is the role of coenzyme Q (ubiquinone) in the ETC?
Coenzyme Q shuttles electrons from Complex I and II to Complex III.
What is the role of cytochrome c in the ETC?
Cytochrome c transfers electrons one at a time from Complex III to Complex IV.
What is the role of FMN in the ETC?
FMN transfers electrons from NADH to Fe-S clusters in Complex I.
What is the role of Fe-S clusters in the ETC?
Fe-S clusters facilitate electron transfer in Complexes I, II, and III.
What is the role of copper in the ETC?
Copper reduces oxygen to water in Complex IV.
What is the function of Complex I in the ETC?
Complex I accepts electrons from NADH and transfers them to ubiquinone (CoQ), pumping 4 protons into the intermembrane space.
What is the function of Complex II in the ETC?
Complex II accepts electrons from FADH2 and transfers them to ubiquinone. It does not pump protons, resulting in a low ATP yield.
What is the function of Complex III in the ETC?
Complex III receives electrons from ubiquinol and transfers them to cytochrome c, pumping 4 protons into the intermembrane space. It also involves the Q cycle.
What is the function of Complex IV in the ETC?
Complex IV receives electrons from cytochrome c and transfers them to oxygen, reducing oxygen to water. It pumps 2 protons into the intermembrane space.
What is the chemiosmotic theory?
The chemiosmotic theory, proposed by Peter Mitchell, states that the proton gradient (protonmotive force) across the inner mitochondrial membrane drives ATP synthesis.
What is the role of ATP synthase in the ETC?
ATP synthase uses the proton gradient to synthesize ATP from ADP and Pi.
What is the P/O ratio for NADH and FADH2?
For NADH, the P/O ratio is 2.5 ATP. For FADH2, the P/O ratio is 1.5 ATP.
What is the role of the Q cycle in Complex III?
The Q cycle in Complex III involves the transfer of electrons from ubiquinol to cytochrome c, regenerating ubiquinone and pumping protons into the intermembrane space.
What is the final electron acceptor in the ETC?
Oxygen (O2) is the final electron acceptor, which is reduced to water.
What is the role of the intermembrane space in the ETC?
The intermembrane space accumulates protons pumped by Complexes I, III, and IV, creating a proton gradient used to drive ATP synthesis.
What is the role of the matrix in the ETC?
The matrix contains enzymes for the TCA cycle, fatty acid oxidation, and mitochondrial DNA. It is where NADH and FADH2 are produced.
What is the function of dinitrophenol (DNP) in the ETC?
Dinitrophenol is an uncoupler that disrupts the proton gradient by allowing protons to leak back into the matrix, inhibiting ATP synthesis and dissipating energy as heat.
What is the role of the glycerol phosphate shuttle?
The glycerol phosphate shuttle transfers cytosolic NADH to the mitochondrial matrix, converting it to FADH2, which enters the ETC at Complex II, yielding 1.5 ATP per NADH.
What is the role of the malate-aspartate shuttle?
The malate-aspartate shuttle transfers cytosolic NADH to the mitochondrial matrix without losing electrons, allowing NADH to enter the ETC at Complex I, yielding 2.5 ATP per NADH.
What is the role of superoxide dismutase in the ETC?
Superoxide dismutase converts superoxide radicals (O2-) into hydrogen peroxide (H2O2), which is then broken down by catalase into water and oxygen.
What is the role of catalase in the ETC?
Catalase breaks down hydrogen peroxide (H2O2) into water and oxygen, preventing the accumulation of reactive oxygen species.
How many protons are pumped by Complex I per NADH?
Complex I pumps 4 protons into the intermembrane space per NADH.
How many protons are pumped by Complex III per QH2?
Complex III pumps 4 protons into the intermembrane space per QH2.
How many protons are pumped by Complex IV per O2?
Complex IV pumps 2 protons into the intermembrane space per O2.
