Test Bank for Lehninger Principles of Biochemistry, 8th Edition by David L. Nelson
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Course
Biochemistry
Institution
Biochemistry
Test Bank for Lehninger Principles of Biochemistry 8e 8th Edition by David L. Nelson, Michael M. Cox. ISBN-13: 8002 Full chapters test bank PDF 1. The Foundations of Biochemistry I STRUCTURE AND CATALYSIS 2. Water, the Solvent of Life 3. Amino Acids, Peptides, and Proteins 4. The Three-Dimensional ...
Biochemistry 8th Edition By David L. Nelson;
b b b b b b b
Michael M. Cox All Chapters 1-28 LATES
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What is an oxidant? What is a reductant? - ANSWER> Oxidant is
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b b b
molecule that accepts electrons.
b b b b
Reductant is molecule that donates electronsb b b b b
7) Identify the oxidant and reductant in following rxn.
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Pyruvate + NADH + H^+ --------> lactate + NAD^+ -
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ANSWER> Oxidant is Pyruvate
b b b b
Reductant is NADH b b
8) How is redox potential related to the free-energy change of a
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reaction? - ANSWER> Delta G not prime = -nF(delta E not prime)
b b bv b b b b b b b b b
15) Amytal is a barbiturate sedative that inhibits electron flow
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through complex 1. How would the addition of amytal to
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actively respiring mitochondria affect the relative oxidation-
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reduction states of the components of ETC and TCA? -
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ANSWER> Complex I would be reduced where as Complex II,
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III, an IV would be oxidized. TCA would halt because it has no
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way to oxidize NADH.
b b b b
16) What is the advantages of having Complexes I, III, and IV
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associated with one another in the form of a respirasome?
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-
,ANSWER> Enhances the efficiency of electron flow from one
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complex to another. Causing more efficient proton pumping.
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17) What citric acid cycle enzyme is also a component of the
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b ETC? - ANSWER> Succinate Dehydrogenase
b bv b b
18) What are the R.O.S an why are they dangerous? - ANSWER>
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b
b Hydroxyl radical (OH.) Hydrogen peroxide (H2O2), superoxide
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b ion (O2-), and peroxide (O2 2-). They disrupt cell structure and
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b function
22) What is the mechanistic basis for the observation that the
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binhibitors of ATP synthase also lead to an inhibition of the ETC?
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- ANSWER> If proton gradient is dissipated by influx of protons
v
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bwith generation of ATP, eventually outside of Mitochondrion
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bdevelops such a large positive charge ETC can no longer
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b pump E- against gradient. b b b
23) What cause C subunit of ATP synthase to rotate? What
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determines direction? - ANSWER> Josteled by thermal
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benergy. Proton gradient makes clockwise rotations more likely
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because that direction results in protons flowing down
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concentration gradient.
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24) Conduction of protons by F not unit of ATP synthase is b b b b b b b b b b
blocked by dicyclohexylcarbodiimide, which reacts readily with
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carboxyl groups. What are the most likely targets of action of
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this reagent? How might you use site specific mutagenesis to
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help? - ANSWER> Most likely target is aspartate and glutamate
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,side chains. Conversion of Asp 61 into asparagine by site
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bspecific mutagenesis eliminates concentration gradients.
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25) Most common sign metabolic sign of mitochondrial
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bdisorders is lactic acidosis. Why? - ANSWER> Only means of
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bgenerating ATP is anaerobic glycolysis which will lead to b b b b b b b b
baccumulation of lactic acid in blood. b b b b b
26) How does the inhibition of ATP-ADP translocase affect
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T.C.A? Glycolysis? - ANSWER> If ADP cannot get into
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mitochondrion, ETC will cease to function because there will
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be no acceptor for the energy. NADH will build up in the
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matrix. Inhibiting parts of T.C.A. Glycolysis will switch to lactic
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acid fermentation so NADH can be reoxidizes to NAD+ by
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lactate dehydrogenase.
b b
28) The number of molecules of inorganic phosphate
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incorporated into organic form per atom of oxygen consumed,
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termed P:O ration.
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A) What is relation of the P:O ratio to the ratio of the number
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of protons translocated per electron pair and the ratio of the
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number of protons needed to synthesize ATP and transport it
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to cytoplasm?
b b
B) What are the P:O ration of electrons donated by matrix
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NADH and by succinate? - ANSWER> The P:O ratio is equal
b b b b b bv b b b b b
to the product
b b b
, 30) Suppose that the mitochondrion of patient ozidizes NADH
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irrespectively of whether ADP is present.Predict the likely
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symptoms? - ANSWER> Oxidation and phosphorylation were not
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tightly coupled. So much of her energy of fuel molecules was
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converted to heat rather than ATP.
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33) Uncouplers were suggested to make wonderful diet drugs. b b b b b b b
Explain why this ide was proposed and denied? - ANSWER> If
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oxidative phosphorylation were uncoupled, no ATP could be
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produced. In an attempt to make ATP, much fuel would be
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consumed.
b
34) If actively respiring mitochondrion are exposed to an
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inhibitor of ATP-ADP translocase, the ETC exist to operate.
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Why? - ANSWER> If ATP/ADP cannot exchange between matrix
b b v
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and mitochondrion, ATP synthase will cease to function
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because its substrate, ADP, is absent. Proton gradient will
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become so large ETC will not be able to pump protons against it.
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37) An arginine residue (Arg 210) in the subunit of E. Coli ATP
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synthase is near the aspartate residue (Asp 61) in the matrix side
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proton channel. How might Arg 210 assist proton flow? -
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ANSWER> Arginine residue, with positive charge, will facilitate
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proton release from aspartic acid by stabilizing negatively
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charged aspartate.
b b
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