BICH 411: EXAM 2
50 Cards in this Set
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In the TCA cycle, carbon enters the cycle as ____ and exits as ____ with metabolic energy captured as ____, ____, ____.
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acetyl CoA; CO2; ATP; NADH; [FADH2]
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In eukaryotic cells, glycolysis occurs in the ____ and the TCA cycle reactions take place in ____.
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cytoplasm; mitochondria
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The pyruvate dehydrogenase complex contains three multimeric enzymes (E1pdh, E2ta, and E3dld). All are properties of E1pdh EXCEPT...
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it binds NAD+ in its active site
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Order the coenzymes according to their involvement in the pyruvate dehydrogenase complex.
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TPP, Lipoate (lipoamide), CoA-SH, [FAD], NAD+
(C, D, B, E, A)
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All are correct statements about the reaction catalyzed by citrate synthase EXCEPT...
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citrate synthase is allosterically activated by ATP
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Citrate synthase has a ____ deltaG and is essentially ____ due to the ____ of the CoA thioester.
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large negative; irreversible; hydrolysis
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____ catalyzes citrate isomerization by abstracting ____ from citrate to yield the enzyme-bound intermediate ____, followed by ____ to produce isocitrate.
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aconitase; water; cis-aconitate; rehydration
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In mammalian tissues, isocitrate dehydrogenase is allosterically stimulated by...
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high NAD+/NADH and high ADP/ATP ratios
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The succinate dehydrogenase mechanism involves the ____ of succinate, which is exergonic and can be used to provide for the ____.
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oxidation; reduction of [FAD]
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Fumerase catalyzes a reaction for which each of the following is true EXCEPT...
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all are true
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The oxidation of malate to oxaloacetate is not thermodynamically favored under standard conditions. It occurs because...
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oxaloacetate is used in the next reaction, which has a negative deltaG
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In the TCA cycle (reactions 1-8), ____ oxidation(s) use(s) NAD+ as the oxidizing agent while ____ oxidation(s) use(s) FAD as the oxidizing agent.
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3; 1
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The three reactions of the citric acid cycle with large negative deltaG values include...
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citrate synthase, isocitrate dehydrogenase; alpha-ketoglutarate dehydrogenase
(A, C, D)
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All are principal allosteric regulatory "signals" controlling the TCA cycle activity EXCEPT...
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all are true
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The only reaction of the citric acid cycle that provides substrate-level-phosphorylation is catalyzed by...
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succinyl-CoA synthetase
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Which enzymes of the TCA cycle (reactions 1-8) catalyze oxidative decarboxylation reactions?
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isocitrate dehydrogenase and succinate dehydrogenase
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Fluoroacetate is a potent inhibitor of the TCA cycle. Which step of the TCA cycle is inhibited as a result of fluoroacetate entering the TCA cycle?
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aconitase
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All are true statements for the glyoxylate pathway EXCEPT...
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glyoxysomes contain all of the enzymes for the glyoxylate cycle
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ATP made in glycolysis and the TCA cycle is the result of ____ phosphorylation, and NADH-dependent ATP synthesis is the result of ____ phosphorylation.
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substrate-level; oxidative
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Reduction involves the ____ of electron(s), and reactions for which the reduction potential is ____ are spontaneous under standard conditions.
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gain; positive
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Each of the following is a true statement EXCEPT...
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for the redox reactions with negative reduction potentials, standard free energy change is negative
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Where does the energy that drives ATP synthesis come from?
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the proton gradient
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Which of the following is a two-electron donor?
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NADH
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The first half of the Q cycle results in which of the following?
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a semiquinone radical (UQ*-) in the Qn site
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Complex III takes up ____ proton(s) on the matrix side of the ____ membrane and releases ____ protons on the intermembrane-space side for each pair of ____ passed through the Q cycle.
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two; inner; four; electrons
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All are characteristics of cyt c EXCEPT...
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all are true
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The complete reduction of one molecule of oxygen gas requires how many electrons?
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four
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All of the following transfer electrons to the UQ/UQH2 pool EXCEPT...
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complex IV
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Which of the following complex(es) translocate protons into the inner mitochondrial membrane space?
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complexes I, III, and IV
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Which of the following correctly and completely describes electron movement in electron transport?
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NADH --> complex I --> coenzyme Q --> complex III --> cytochrome c --> complex IV --> O2
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All of the following are properties of ATP synthase EXCEPT...
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the Fo subunit is hydrophilic
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The hypothesis for proton driven ATP synthesis depends on proton neutralization of the negative charge on c-subunit ____ side chain as the rotor turns. This causes the ____-subunit to turn relative to the three ____-subunits.
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Asp; gamma; beta
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If an ATP synthas contains 12 c subunits, 3 alpha subunits, and 3 beta subunits, how many protons must pass through this complex for every ATP molecule synthesized and transported to the cytosol, assuming that each ATP synthesized also requires one proton for transport to the cytosol.
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5
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Which of the following is an inhibitor of complex IV?
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cyanide
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P/O ratio is defined as...
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molecules of ATP formed per two electrons flowing through electron transport chain
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A characteristic of the glycerophosphate shuttle is...
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it shuttles "NADH electron equivalents" across the mitochondrial membrane to yield 1.5 ATP/NADH
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Photosynthesis occurs in photosynthetic ____ localized in large organelles known as ____.
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membranes; chloroplasts
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The reaction of photosynthesis whereby light energy is transduced into chemical energy uses ____ as a source of carbon to produce ____.
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CO2; hexose
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All are contained by chloroplasts EXCEPT...
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all are true
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Complete the following reaction:
__NADPH + __H+ + __ATP + __CO2 + 12H2O -->
C6H12O6 + 12 NADPH+ +18ADP + 18Pi
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12; 12; 18; 6
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Chloroplasts differ from mitochondria in that...
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in chloroplasts, the proton gradient is generated between the thylakoid lumen and the stroma
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One of the light reactions in photosynthetic plants...
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involves the splitting of two water molecules, producing molecular oxygen
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Chlorophyll is located in the ____ of the chloroplast.
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thylakoid membranes associated with proteins
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How many photons of light must be absorbed by PSII for the oxidation of 2 water molecules to form one oxygen molecule?
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4
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Photophosphorylation is the term for...
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ATP synthesis driven by light energy
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Photophosphorylation and oxidative phosphorylation are similar processes. All of the following are common to BOTH processes EXCEPT...
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both produce NADPH to be used in the reductive pentose phosphate pathway (Calvin cycle)
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Characteristics of the chloroplast's ATP synthase include all EXCEPT...
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all are true
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____ and ____ are produced in the light reactions of photosynthesis which are then used to convert ____ to ____ in the dark reactions.
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ATP; NADPH; carbon dioxide; sugar
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All are correct statements about RuBisCO EXCEPT...
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it releases two molecules of glyceraldehyde-3-phosphate as products
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Many of the enzymes of the Calvin cycle are also involved in ____; however, the glyceraldehyde-3-phosphate dehydrogenase of the Calvin cycle is specific for ____.
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glycolysis; NADPH
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