27. Since the electrons from both NADH and FADH2 end up being carried by ubiquin

Question

27. Since the electrons from both NADH and FADH2 end up being carried by ubiquinone, why would the electrons from NADH have a bigger impact on ATP generation?

28. The protein complex responsible using the proton motive force to make ATP is the mitochondrial F1 F0ATPase. This complex has multiple subunits including ?,?,?, a, b and c. Which of the subunits actually contains the channel that protons move through?

29. Once ATP is synthesized in the mitochondria how is it distributed to the rest of the cell?

30. We presented examples of inhibitors and uncouplers during our discussion of oxidative phosphorylation. Inhibitors and uncouplers act by different mechanisms. What is the definition of an uncoupler?

Explanation / Answer

27) NADH generates 3 ATP molecules during the Electron Transport Chain with oxidative phosphorylation as NADH donates its electron to Complex 1 getting oxidised itself, Complex 1 is at a greater energy level than the other Complexes in the ETC. Subsequently, when the Complex 1 passes on the electron to Complex 3, energy is released to pump protons across the membrane, creating an electro-chemical gradient. Finally, the electron moves to Complex 4 and again transfers more electrons across the membrane creating a gradient. As NADH started with Complex 1, it has more chances to pump protons across the membrane gradient, which runs the ATP synthase and gives us ATP energy units per molecule of NADH. FADH2 on the other hand produces 2 ATP during the Electron Transport Chain because it transfers its electron to Complex 2, without passing through Complex 1. By skipping Complex 1, it misses a chance to pump protons across the membrane to create a gradient, so lower nummber of protons can be been pumped by the time it reaches Complex 4. Protons still have been pumped, enough to power 2 ATP created by ATP synthase. Complex 2 contains nothing but Ubiquinone.

28) F-ATPase contains two domains - 1) Fo domain, which is inside the membrane 2) F1 Domain which is peripheral to the membrane or in the intermembrane space.

The F1 contains 3?, 3?, 1?, 1?, 1? subunits. Fo contains subunits c, a, b, d, F6, OSCP and some other non-functional subunits. The protons bind to the subunits of the Fo domains b and d.

29) ADP/ATP translocases is a active transport channel that transports ATP out of Mitochondria and takes in used ATP in the form of ADP across the inner mitochondrial membrane. Free ADP is translocated from the cytoplasm of the cell to matrix inside the intermembrane space of Mitochondria, meanwhile the ATP produced from oxidative phosphorylation after Electron Transport chain is transported from the mitochondrial matrix to the protoplasm of the cell, thereby providing the cells with its main energy unit - ATP.

30) Uncoupler by definition is an agent that unlinks two integrated series of chemical reactions. In most cases it is used to dissociate two chemical reactions, one that prevents the formation of ATP (energy unit of cell) in oxidative phosphorylation in mitochondria by dissociating the Phosphorylation reaction, from those concerned with electron transport and oxidation (ETC). Uncoupling Agents cause loss of Energy in cell by leakage in Proton Gradient.

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