BCCB2000 Lecture 20 Questions Flashcards
(29 cards)
The standard reduction potential E’° of any redox pair is defined by the following: oxidizing agent + n electrons —> reducing agent The E’° values for the NAD+/NADH, furmate/succinate, pyruvate/lactate, FAD/FADH2 conjugate redox pairs are -0.32V, 0.031V, -0.19V and -0.22V respectively. Formation of NADH, lactate, succinate, and FADH2 all requires 2 electrons. Which conjugate redox pair is the stronger oxidizing agent? A. NAD+/NADH B. pyruvate/lactate C. FAD/FADH2 D. fumarate/succinate
fumarate/succinate
A new compound isolated from mitochondria is claimed to represent a previously unrecognized carrier in the electron transfer chain. It is given the name coenzyme Z. Which line of evidence do you feel is the least conclusive in assigning this compound a position in the electron transfer chain? A. When added to a mitochondrial suspension coenzyme Z is taken up very rapidly and specifically by the mitochondria. B. Removal of coenzyme Z from the mitochondria results in a decreased rate of oxygen consumption. C. Alternate oxidation and reduction of the mitochondrion-bound coenzyme Z can be readily demonstrated. D. The rate of oxidation and reduction of mitochondrion-bound coenzyme is of the same order of magnitude as the overall rate of electron transfer in mitochondria as measured by oxygen consumption. E. Inhibition of coenzyme Z in the mitochondria results in a decreased rate of oxygen consumption.
A. When added to a mitochondrial suspension
coenzyme Z is taken up very rapidly and specifically by the mitochondria.
NAD and NADP dependent dehydrogenases catalyze substrates by transferring ________ to C-4 of NAD+ and NADP+.
A. one electron
B. two electrons
C. one electron and one proton
D. two electrons and one proton
E. two electrons and two protons
D
Which of the following statements about the chemiosmotic theory is correct?
A. Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane.
B. The effect of uncoupling reagents is a consequence of their ability to carry electrons through membranes.
C. It predicts that oxidative phosphorylation can occur even in the absence of an intact inner mitochondrial membrance.
D. The membrane ATP synthase has no significant role in the chemiosmotic theory.
E. All of the above are correct.
A. Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane.
The standard reduction potential E’° of any redox pair is defined by the following:
oxidizing agent + n electrons —> reducing agent
The E’° values for the NAD+/NADH, fumarate/succinate, pyruvate/lactate, FAD/FADH2 conjugate redox pairs are -0.32V, 0.031V, -0.19V, and -0.22V respectively. Formation of NADH, lactate, succinate, and FADH2 all requires 2 electrons.
What is the equilibrium constant (K’eq) for the reaction below assuming that there is 1M concentration of each reactant and product at pH 7 and temperature = 25°C?
Pyruvate + NADH + H+ <—> lactate + NAD+
A. 2.49 x 105
B. 2.49 x 103
C. 2.49 x 106
D. 2.49 x 104
D. 2.49 x 10^4
ΔG’°= -RT ln K’eq. Temperature in Kelvin hence 25°C = 298K
-25084 = -8.315 x 298 ln K’eq
-25084/-2477.87 = ln K’eq
10.1235 = ln K’eq
e10.1235 = K’eq = 2.49 x 104
Oxidative phosphorylation in mitochondria is often monitored by measuring oxygen consumption. When oxidative phosphorylation proceeds rapidly the mitochondria will also rapidly consume oxygen. If there is little oxidative phosphorylation, then only small amounts of oxygen will be used. Assume that you are given a suspension of intact, isolated, mitochondria and that you are directed to add glucose first followed a little later by adding both ADP and Pi. Assume also that the mitochondria are initially depleted of TCA cycle intermediates. Predict, and explain, the effect of adding glucose followed by both ADP and Pi on: (1) oxygen consumption (above basal levels) and (2) the synthesis of ATP by the isolated mitochondria.
A. ATP synthesis will increase
B. ATP synthesis will decrease
C. oxygen consumption will increase
D. ATP synthesis will not change
E. oxygen consumption will not change
F. oxygen consumption will d
D. ATP synthesis will not change
E. oxygen consumption will not change
Oxidative phosphorylation in mitochondria is often monitored by measuring oxygen consumption. When oxidative phosphorylation proceeds rapidly the mitochondria will also rapidly consume oxygen. If there is little oxidative phosphorylation, then only small amounts of oxygen will be used. Assume that you are given a suspension of intact, isolated, mitochondria and that you are directed to add succinate followed a little later by both ADP and Pi. Assume also that the mitochondria are initially depleted of TCA cycle intermediates. Predict, and explain, the effect of adding succinate followed a little later by both ADP and Pi on: (1) oxygen consumption (above basal levels) and (2) the synthesis of ATP by the isolated mitochondria.
A. ATP synthesis will increase
B. oxygen consumption will not change
C. ATP synthesis will not change
D. oxygen consumption will decrease
E. oxygen consumption will increase
F. ATP synthesis w
A. ATP synthesis will increase
E. oxygen consumption will increase
The ʺ+ʺ sign in NAD+ indicates that A. this is the reduced form of the coenzyme. B. the nitrogen atom has a positive charge. C. the entire molecule is positively charged. D. it can bind to negatively charged proteins only
B. the nitrogen atom has a positive charge.
Oxidative phosphorylation in mitochondria is often monitored by measuring oxygen consumption. When oxidative phosphorylation proceeds rapidly the mitochondria will also rapidly consume oxygen. If there is little oxidative phosphorylation, then only small amounts of oxygen will be used. Assume that you are given a suspension of intact, isolated, mitochondria and that you are directed to add succinate. Assume also that the mitochondria are initially depleted of TCA cycle intermediates. Predict, and explain, the effect of adding succinate on: (1) oxygen consumption (above basal levels) and (2) the synthesis of ATP by the isolated mitochondria.
A. ATP synthesis will not change
B. oxygen consumption will increase
C. ATP synthesis will decrease
D. oxygen consumption will not change
E. ATP synthesis will increase
F. oxygen consumption will decrease
A. ATP synthesis will not change
D. oxygen consumption will not change
True or False? The proton concentration in the mitochondrial intermembrane space is relatively greater than the proton concentration in the mitochondrial matrix and this means that is also should be much greater than the proton concentration in the cytosol.
False
Oxidative phosphorylation in mitochondria is often monitored by measuring oxygen consumption. When oxidative phosphorylation proceeds rapidly the mitochondria will also rapidly consume oxygen. If there is little oxidative phosphorylation, then only small amounts of oxygen will be used. Assume that you are given a suspension of intact, isolated, mitochondria and that you are directed to add succinate. Assume also that the mitochondria are initially depleted of TCA cycle intermediates. Predict, and explain, the effect of adding succinate on: (1) oxygen consumption (above basal levels) and (2) the synthesis of ATP by the isolated mitochondria.
A. oxygen consumption will increase
B. oxygen consumption will not change
C. ATP synthesis will increase
D. oxygen consumption will decrease
E. ATP synthesis will decrease
F. ATP synthesis will not change
B. oxygen consumption will not change
F. ATP synthesis will not change
If the standard reduction potential of a certain half-reaction is -0.30 V, which statement below is true for this half-reaction to proceed as a reduction?
A. This half-reaction will proceed if it is coupled to another half-reaction that has a standard reduction potential greater than +0.30 V.
B. This half-reaction will proceed if it is coupled to another half-reaction that has a standard reduction potential greater than -0.30 V.
C. This half-reaction will proceed if it is coupled to another half-reaction that has a standard reduction potential less than -0.30 V.
D. It doesnʹt matter what half-reaction this is coupled with, it will proceed spontaneously
C. This half-reaction will proceed if it is coupled to another half-reaction that has a standard reduction potential less than -0.30 V.
What chemical characteristics of ubiquinone make it uniquely useful in the electron transfer chain? A. It has a quinone ring which allows electrons to resonate over the structure. It is lipid soluble and can move within the mitochondrial outer membrane. It is a static electron carrier. B. It has a quinone ring which allows electrons to resonate over all the structure. It is lipid soluble and can move within the mitochondrial inner membrane. It is a mobile electron carrier. C. It has a pyrodoxal ring which allows electrons to resonate over all the structure. It is lipid soluble and can move within the mitochondrial inner membrane. It is a static electron carrier. D. It has a quinone ring which allows electrons to be fixed over its structure. It is lipid soluble and can move within the mitochondrial inner membrane. It is a mobile electron carrier. E. It has a ubiquinone ring which allows electrons to be fixed over all
B. It has a quinone ring which allows electrons to resonate over all the structure. It is lipid soluble and can move within the mitochondrial inner membrane. It is a mobile electron carrier.
Almost all of the oxygen (O2) one consumes in breathing is converted to: A. carbon dioxide (CO2). B. carbon monoxide and then to carbon dioxide. C. water. D. acetyl-CoA. E. none of the above.
C. water.
Oxidative phosphorylation in mitochondria is often monitored by measuring oxygen consumption. When oxidative phosphorylation proceeds rapidly the mitochondria will also rapidly consume oxygen. If there is little oxidative phosphorylation, then only small amounts of oxygen will be used. Assume that you are given a suspension of intact, isolated, mitochondria and that you are directed to add glucose. Assume also that the mitochondria are initially depleted of TCA cycle intermediates. Predict, and explain, the effect of adding glucose on: (1) oxygen consumption (above basal levels) and (2) the synthesis of ATP by the isolated mitochondria.
A. oxygen consumption will not change
B. ATP synthesis will not change
C. ATP synthesis will increase
D. oxygen consumption will decrease
E. oxygen consumption will increase
F. ATP synthesis will decrease
A. oxygen consumption will not change
B. ATP synthesis will not change
During oxidative phosphorylation, the proton motive force that is generated by electron transport is used to:
A. reduce O2 to H2O.
B. oxidize NADH to NAD+.
C. generate the substrates (ADP and Pi) for the ATP synthase.
D. induce a conformational change in the ATP synthase which leads to the synthesis of ATP.
E. create a pore in the inner mitochondrial membrane.
D. induce a conformational change in the ATP synthase which leads to the synthesis of ATP.
It is important that the inner mitochondrial membrane is impermeable to protons because: A. this allows the mitochondrial matrix to have more protons relative to the mitochondrial intermembrane space B. this allows the mitochondrial intermembrane space to have less protons relative to the mitochondrial matrix C. this allows the coupling between and protons and ADP synthesis. D. this allows the coupling between electron transport and ATP synthesis. D. this allows the coupling between electron transport and ATP synthesis.
D. this allows the coupling between electron transport and ATP synthesis.
Oxidative phosphorylation in mitochondria is often monitored by measuring oxygen consumption. When oxidative phosphorylation proceeds rapidly the mitochondria will also rapidly consume oxygen. If there is little oxidative phosphorylation, then only small amounts of oxygen will be used. Assume that you are given a suspension of intact, isolated, mitochondria and that you are directed to add glucose first followed a little later by adding both ADP and Pi and then followed even later by adding citrate. Assume also that the mitochondria are initially depleted of TCA cycle intermediates. Predict, and explain, the effect of adding glucose followed by both ADP and Pi and then finally citrate on: (1) oxygen consumption (above basal levels) and (2) the synthesis of ATP by the isolated mitochondria.
A. oxygen consumption will not change
B. oxygen consumption will decrease
C. ATP synthesis will not change
D. oxygen consumpti
D. oxygen consumption will increase
E. ATP synthesis will increase
True or False? The difference in concentration of protons between the mitochondrial matrix and the mitochondrial intermembrane space is due to the activity of membrane proteins that actively ‘pump’ electrons from one side of the inner mitochondrial membrane to the other.
False
The standard reduction potential E’° of any redox pair is defined by the following:
oxidizing agent + n electrons —> reducing agent
The E’° values for the NAD+/NADH, fumarate/succinate, pyruvate/lactate, FAD/FADH2 conjugate redox pairs are -0.32V, 0.031V, -0.19V, and -0.22V respectively. Formation of NADH, lactate, succinate, and FADH2 all requires 2 electrons.
Which conjugate redox pair is the stronger oxidizing agent?
A. pyruvate/lactate
B. NAD+/NADH
C. FAD/FADH2
D. fumarate/succinate
D. fumarate/succinate
Statement: Reduction potentials are related to the generation of free energy in the electron transport chain. Reason: The electron transport chain is a series of oxidation-reduction reactions and so each reaction will have a reduction potential.
Statement is True; Reason is True; the reason is an incorrect explanation of the statement
The chemiosmotic hypothesis explains: A. How the exergonic free energy of electron transport is coupled to the endergonic requiring proton pumps B. How the transmembrane flow of electrons provides the free energy necessary for the synthesis of ATP C. How the transmembrane flow of protons provides the free energy necessary for the synthesis of ATP D. How the endergonic free energy of electron transport is coupled to the exergonic requiring proton pumps
A. How the exergonic free energy of electron transport is coupled to the endergonic requiring proton pumps C. How the transmembrane flow of protons provides the free energy necessary for the synthesis of ATP
True or False? The proton concentration in the mitochondrial matrix is relatively less than the proton concentration in the mitochondrial intermembrane space. True
True
he standard reduction potential E’° of any redox pair is defined by the following:
oxidizing agent + n electrons —> reducing agent
The E’° values for the NAD+/NADH, fumarate/succinate, pyruvate/lactate, FAD/FADH2 conjugate redox pairs are -0.32V, 0.031V, -0.19V, and -0.22V respectively. Formation of NADH, lactate, succinate, and FADH2 all requires 2 electrons.
Beginning with 1M concentrations of each reactant and product at pH 7 and 25°C, which direction will the reaction proceed (i.e. from pyruvate to lactate or the reverse) and what is its Free Energy ΔG’°?
Pyruvate + NADH + H+ <—> lactate + NAD+
A. lactate to pyruvate; ΔG’° = -35.58 kJ/mol
B. pyruvate to lactate; ΔG’° = -25.1 kJ/mol
C. pyruvate to lactate; ΔG’° = -98.41 kJ/mol
D. lactate to pyruvate; ΔG’° = -984.1 kJ/mol
B. pyruvate to lactate; ΔG’° = -25.1 kJ/mol
