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5 Cards in this Set
- Front
- Back
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Consider the following experiment. Carefully isolated liver mitochondria are incubated in the presence of a limiting amount of malate. Three minutes after adding the substrate, cyanide is added, and the reaction is allowed to proceed for another 7 minutes. At this point, which of the following components of the electron-transfer chain will be in an oxidized state? A. Complex I B. Complex II C. Complex III D. Coenzyme Q E. Cytochrome C |
B. Complex II
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Consider the following experiment. Carefully isolated liver mitochondria are placed in a weakly buffered solution. Malate is added as an energy source, and an increase in oxygen consumption confirms that the electron-transport chain is functioning properly within these organelles. Valinomycin and potassium are then added to the mitochondrial suspension. Valinomycin is a drug that allows potassium ions to freely cross the inner mitochondrial membrane. What is the effect of valinomycin on the proton motive force that had been generated by the oxidation of malate? A. The proton motive force will be reduced to a value of zero. B. There will be no change in the proton motive force. C. The proton motive force will be increased. D. The proton motive force will be decreased but to a value greater than zero. E. The proton motive force will be decreased to a value less than zero. |
D. The proton motive force will be decreased but to a value greater than zero.
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Dinitrophenol acts as an uncoupler of oxidative phosphorylation by which of the following mechanisms? A. Activating the H-ATPase B. Activating coenzyme Q C. Blocking proton transport across the inner mitochondrial membrane D. Allowing for proton exchange across the inner mitochondrial membrane E. Enhancing oxygen transport across the inner mitochondrial membrane |
D. Allowing for proton exchange across the inner mitochondrial membrane
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A 25-year-old woman presents with chronic fatigue. A series of blood tests is ordered, and the results suggest that her red blood cell count is low because of iron deficiency anemia. Such a deficiency would lead to fatigue because of which of the following? A. Her decrease in Fe–S centers is impairing the transfer of electrons in the electron-transport chain. B. She is not producing enough H2O in the electrontransport chain, leading to dehydration, which has resulted in fatigue. C. Iron forms a chelate with NADH and FAD(2H) that is necessary for them to donate their electrons to the electron-transport chain. D. Iron acts as a cofactor for -ketoglutarate DH in the TCA cycle, a reaction required for the flow of electrons through the electron-transport chain. E. Iron accompanies the protons that are pumped from the mitochondrial matrix to the cytosolic side of the inner mitochondrial membrane. Without iron, the proton gradient cannot be maintained to produce adequate ATP. |
A. Her decrease in Fe–S centers is impairing the transfer of electrons in the electron-transport chain.
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Which of the following would be expected for a patient with an OXPHOS disease? A. A high ATP:ADP ratio in the mitochondria B. A high NADH:NAD ratio in the mitochondria C. A deletion on the X chromosome D. A high activity of complex II of the electrontransport chain E. A defect in the integrity of the inner mitochondrial membrane |
B. A high NADH:NAD ratio in the mitochondria
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