Homework Questions: Exam 3 Flashcards by Emma Sellers

Which of the following is true regarding the glucose transporter?

a) in addition to glucose, it will transport any other monosaccharide with six carbons
b) binding of glucose causes a conformational change so that the transporter is never open on both sides of the membrane
c) ATP hydrolysis prevents the transporter from working in reverse
d) it is able to transport glucose into a cell against a concentration gradient
e) none of the above

b) binding of glucose causes a conformational change so that the transporter is never open on both sides of the membrane

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which of the following statements most accurately defines the term “symport”?

a) a protein which transports two substances in the same direction
b) a protein which transports two substances in the same direction up their concentration gradients
c) a protein which transports two substances in opposite directions up their concentration gradients
d) a protein which transports two substances in opposite directions

a) a protein which transports two substances in the same direction

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which of the following statements most accurately defines the term “antiport”?

a) a protein which transports two substances in the same direction
b) a protein which transports two substances in the same direction up their concentration gradients
c) a protein which transports two substances in opposite directions
d) a protein which transports two substances in opposite directions up their concentration gradients

c) a protein which transports two substances in opposite directions

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which of the following statements correctly distinguishes transporters (carrier proteins) from porins and ion channels?

a) transporters exhibit a conformational change when substrate binds but porins and ion channels do not
b) porins and ion channels have permanent hole that passes from one side of the membrane to the other through which solutes pass whereas transporters do not
c) porins and ion channels mediate passive transport, while transporters are associated with both passive and active transport
d) both A and B are correct
e) all of the above are correct

e) all of the above are correct

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an ion transport protein constructed entirely from B strands is most likely to be…

a) a porin
b) a gated ion channel
c) an aquaporin
d) an active transport pump

a) a porin

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The compound 6-O-benzyl-D-galactose competes with glucose for binding to the glucose transporter. The figure below shows the kinetics of glucose transport with an without the inhibitor. How would the Km and Vmax values of it compare to those estimated for glucose?

a) Km would decrease; Vmax would decrease
b) Km would be unchanged; Vmax would increase
c) Km would increase; Vmax would increase
d) Km would increase; Vmax would be unchanged

d) Km would increase; Vmax would be unchanged

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the Na,K-ATPas is a(n) _________ that moves Na+ from ________ and K+ from ________.

antiporter; inside to out; outside to in

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If the (Na+-K+)=ATPase transporter were modified so that it could no longer be phosphorylated, which of the following would happen?

a) K+ ions but not Na+ ions would be transported
b) Na+ ions but not K+ ions would be transported
c) no ions would be transported
d) ions would be transported down their concentration gradient

c) no ions would be transported

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given what you know about the function of the (Na+-K+)-ATPase, which of the following is the most accurate prediction of the structure of its binding site? The binding site is likely to contain multiple:

a) glu and asp residues
b) lys and arg residues
c) ser and thr residues
d) gln and asn residues
e) both c and d

a) glu and asp residues

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the primary active transport is usually driven by ________, and secondary active transport by ________.

ATP; an ion gradient

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the (Na+-K+)-ATPase works through changes in conformation. Which of the following mechanisms is responsible for these changes in conformation?

a) induced fit
b) cooperatively
c) allostery
d) phosphorylation

d) phosphorylation

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the conformational changes responsible for ion transport in the Na,K-ATPase are triggered by…

a) attachment and release of a phosphoryl group
b) Na+ binding and K+ release
c) ATP binding and dissociation
d) Na+ binding

a) attachment and release of a phosphoryl group

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an ion will spontaneously move..

a) toward ions with the same charge
b) from an area of high enthalpy to an area of low enthalpy
c) wherever a protein pushes it
d) to an area where it is less concentrated

d) to an area where it is less concentrated

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after depolarization of a nerve cell, what event restores the resting potential?

a) K+ efflux
b) Na+ influx
c) Cl- efflux
d) K+ influx
e) Na+ efflux

a) K+ efflux

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the main difference between active and passive transport systems is…

a) the source of free energy that drives the transport
b) the structure of the membrane transport protein
c) the types of solutes that are transported
d) the importance of the transport of the cell’s usual activities

a) the source of free energy that drives the transport

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Which of the following statements best describes why electrons from FADH2 moving through the electron transport chain contribute less to the proton gradient than electrons from NADH?

a) FADH2 is a prosthetic grou[
b) FADH2 passes its electrons directly to complex III therefore bypassing a portion of the electron transport chain
c) FADH2 has a higher reduction potential than NADH and therefore its electrons must enter the electron transport chain downstream of NADH
d) FADH2 has a lower reduction potential than NADH and therefore its electrons must enter the electron transport chain downstream of NADH

c) FADH2 has a higher reduction potential than NADH and therefore its electrons must enter the electron transport chain downstream of NADH

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what does the reduction potential of 0.815 V for the reduction of water to oxygen indicate?

a) water is very strong reducing agent
b) water is a very strong reducing agent and oxygen is a very stand oxidizing agent
c) oxygen is a very strong oxidizing agent
d) water will be spontaneously reduced to oxygen
e) none of the above

c) oxygen is a very strong oxidizing agent

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if the reduction potential of NAD+ is -0.315 V and the reduction potential for oxygen is 0.815 V, what is the potential for the oxidation of NADH by oxygen?

1.13 V

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acetoacetate may be reduced to 3-hydroxybutyrate. what serves as a better reducing agent?

a) NADH
b) FADH2

a) NADH

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the myoglobin and cytochrome c oxidase content were determined in several animals - hare, sheep, ox, and horse. the levels of both proteins were roughly correlated, i.e., the higher the myoglobin content, the greater the cytochrome c oxidase activity. What conclusions can be drawn about the relationship between the two proteins?

a) the two proteins must interact with one another in some biochemical process
b) the two proteins operate independent of biochemical processes
c) the two proteins inhibit one another
d) none of the above

a) the two proteins must interact with one another in some biochemical process

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for every two electrons transferred from NADH to oxygen, ______ protons are pumped from the matrix to the inter membrane space.

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what is the path of electrons from NADH through the electron transport chain?

a) NADH, Complex I, Q, Complex II, CytC, Complex IV, O2
b) NADH, Complex II, Q, Complex III, CytC, Complex IV, O2
c) NADH, Complex I, Q, Complex III, CytB, Complex IV, O2
d) NADH, Complex I, Q, Complex III, CytC, Complex IV, O2

d) NADH, Complex I, Q, Complex III, CytC, Complex IV, O2

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ubiquinone is a ________ molecule that serves as a ______ electron carrier; cytochrome c is a ________ molecule that serves as a ______ electron carrier

hydrophobic; 2; hydrophilic; 1

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the consumption of acetyl-CoA by the citric acid cycle is DECREASED under which of the following conditions?

a) the concentration of NAD+ is high
b) NADH is rapidly re-oxidized via the electron transport chain
c) the mitochondrial ATP synthase is inactive
d) the concentration of oxaloacetate is high

c) the mitochondrial ATP synthase is inactive

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complex III accepts electrons from ________ and transfers them to ________

ubiquinol; cytochrome c

electrons from FADH2 are delivered to _________, and electrons from NADH are delivered to ________ of the electron transport chain

complex II; complex I

what free radical is thought to be commonly produced by electron transport chain? a) hydroxyl b) peroxyl c) superoxide d) hydrogen peroxyl e) all of the above

c) superoxide

the cytochromes undergo which oxidation reactions?

Fe2+ -----> Fe3+

why does re-oxidation of FADH2 via electron transport chain ultimately produce fewer molecules of ATP than the re-oxidation of NADH? a) a smaller H+ gradient is generated when FADH2 is oxidized compared to that generated by oxidation of NADH b) a larger H+ gradient is generated when FADH2 is oxidized compared to that generated by oxidation of NADH c) electrons from NADH do not pass through complex II d) electrons from FADH2 do not pass through complex II

a) a smaller H+ gradient is generated when FADH2 is oxidized compared to that generated by oxidation of NADH

which of the following is NOT associated with electron transport? a) heme group b) coenzyme Q c) coenzyme A d) iron-sulfur clusters e) flavin mononucleotide

c) coenzyme A

Apolipoproteins are amphipathic because ___________. a) they are composed of hydrophilic and hydrophobic regions b) the transport lipids in an aqueous environment c) they degrade lipids d) they are involved in lipid biosynthesis e) A and B

e) A and B

why is ATP consumed in the initial stage of fatty acid breakdown? a) ATP drives the active transport of fatty acids into mitochondria b) ATP is required to link fatty acids to coenzyme A c) the first step of breakdown is a kinase-catalyzed phosphorylation d) ATP provides oxidizing power for B-oxidation

b) ATP is required to link fatty acids to coenzyme A

during B-oxidation in the peroxisome, what reoxidizes the enzyme-bound FADH2 during the first oxidation of the pathway? a) H2O2 b) O2 c) NAD+ d) FMN e) none of the above

b) O2

each round of B-oxidation of a saturated fatty acyl-CoA produces...

1 NADH, 1 QH2, 1 acetyl-CoA

oxidation of an unsaturated fatty acid requires an additional step catalyzed by a ___________. a) reductase b) hydratase c) synthetase d) thiolase

a) reductase

if the fatty acid 16:0 is catabolized completely, to carbon dioxide and water, the net yield of ATP per molecule of fatty acid is:

130 ATP

the hydrolysis of triacylglycerols stored in adipose tissue is catalyzed by the enzyme _______.

hormone-sensitive lipase

which of the following lipoprotein particles has the greatest relative content (percent weight) of proteins? a) CM b) VLDL c) LDL d) HDL

d) HDL

what are the B-oxidation products of stearic acid, a saturated fatty acid with 18 carbons?

8 NADH, 8 QH2, 9 acetyl-CoA

the substrate for each round of B oxidation is _______.

acetyl-CoA

what transport system moves activated fatty acids from the cytosol to the mitochondrial matrix? a) tracylglycerol shuttle b) glycerol phosphate shuttle c) acyl adenylate shuttle d) lipoprotein shuttle e) carnitine shuttle

e) carnitine shuttle

the products of each round of B oxidation include _______ and ______.

NADH and QH2

during B-oxidation of an odd-chain fatty acid, the last three carbon atoms from the oxidized fatty acid enter the citric acid cycle as ________. a) propionyl-CoA b) methylmalonyl-CoA c) succinyl-CoA d) succinate e) fumarate

c) succinyl-CoA

what enzymes are required to make fatty acids containing 22 or 24 carbons? a) elongases b) reductase c) desaturase d) hydratase

a) elongases

acetyl-CoA carboxylase requires the coenzyme _______ and ______ as an energy source.

biotin and ATP

The portion of the acyl carrier protein that activates the growing fatty acid is similar to the structure of __________.

coenzyme A

what is the final product of fatty acid synthesis? a) acetyl-coa b) palmitoyl-coa c) palimate d) butyric-coa

c) palimate

which of the following is the starting metabolite in ketone body biosynthesis? a) acetyl coa b) amlonyl coa c) acetyl coa and malonyl coa d) acetyl coa and propionyl coa e) propionyl coa

a) acetyl coa

which enzyme is the most important control point for fatty acid synthesis? a) ATP-citrate lyase b) transacylase c) 3-ketoacyl-ACP reductase d) 3-hydroxyacyl-ACP dehydrase e) acetyl-Coa carboxylase

e) acetyl-Coa carboxylase

under which one of the following conditions does the biosynthesis of fatty acids in the liver mainly occur? a) after ingestion of excess tracylglycerols b) high carbohydrate intake c) low carbohydrate intake d) high cholesterol intake e) none of the above

b) high carbohydrate intake

which of the following commonly occurs before cholesterol is packages into a VLDL? a) oxidation to increase water solubility b) esterification with a fatty acid c) phosphorylation by ATP d) hydration of the alkene e) all of the above may occur

b) esterification with a fatty acid

why is HDL commonly referred to as "good cholesterol"?

it returns excess cholesterol from peripheral tissues to the liver where it can be excreted as bile salts

the synthesis of triacylglycerols involves the addition of acyl groups to glycerol-3-phosphate. What is the source of the acyl groups? a) free fatty acid b) fatty acid attached to the acyl carrier protein c) fatty acyladenylate d) acyl-carnitine e) fatty acyl-coa

e) fatty acyl-coa

which of the following is correct regarding the conversion of 3-hydroxy-3-methylglutaryl-coa to mevalonate? a) this reaction requires NADPH, is a key reaction in the synthesis of isoprenoids, and is regulated by cholesterol b) this reaction is regulated by cholesterol c) this is a key reaction in the synthesis of compounds that contain isoprenoid units d) this reaction requires NADPH and is regulated by cholesterol e) this reaction requires NADPH

a) this reaction requires NADPH, is a key reaction in the synthesis of isoprenoids, and is regulated by cholesterol

familial hypercholesterolemia is associated with a deficiency of which of the following? a) HDL receptor protein b) triacylglycerol lipase c) LDL receptor protein d) HMG-CoA synthase e) HMG-CoA reductase

c) LDL receptor protein

in which location listed below foes the following reaction take place? HMG-CoA -----> Acetoacetate + acetyl-coa

mitochondria of liver cells

which of the following explains how phosphatidylserine is synthesized? a) serine displaces the ethanol amine from a phosphatidylethanolamine b) serine reacts with a diacylglycerol pyrophosphate c) CDP-serine reacts with diacylglycerol d) serine reacts with CDP-diacylglycerol e) the ethanol amine group of phosphatidylethanolamine is carboxylated to form serine

a) serine displaces the ethanol amine from a phosphatidylethanolamine

the process of nitrification, nitrate reductase converts ________ into _________.

nitrate; nitrite

which of the following statements about transamination reactions is FALSE? a) they are irreversible, exergonic reactions b) they are used to move nitrogen-containing groups among metabolic intermediates c) they play an important role in gluconeogenesis during fasting d) they use an a-ketoacid and an amino acid as substrates, and they produce an amino acid and an a-ketoacid as products

a) they are irreversible, exergonic reactions

given the following reaction, what is the missing product of the net reaction of glutamine synthetase and glutamate synthase? a-ketoglutarate + NH4+ + NADPH + ATP ----> NADP+ + ADP + Pi + ___________

glutamate

what amino acid is attached to the pyridoxal-5'-phosphate in a typical transaminase?

Lys

how many ATP and electrons are required for the reduction of one molecule of nitrogen to two molecules of ammonia in the reaction catalyzed by nitrogenase? a) 8 ATP and 8 electrons b) 16 ATP and 8 electrons c) 16 ATP and 16 electrons d) 8 ATP and 16 electrons e) 16 ATP and 6 electrons

b) 16 ATP and 8 electrons

in which cellular location listed below does the following reaction take place? arginine ----> urea + ornithine

cytosol

which urea cycle intermediate reacts with carbamoyl phosphate? a) citrulline b) aspartate c) argininosuccinate d) arginine e) ornithine

e) ornithine

Glutamate undergoes a(n) ________, catalyzed by glutamate dehydrogenase, to yield a-ketoglutarate, NADH and ______.

oxidative deamination; ammonia

which of the following statements regarding the metabolism of amino acids in mammals is FALSE? a) it is possible for the carbon skeletons of both glycogenic and ketogenic amino acids to ultimately be found in triacylglycerols b) the carbon skeletons of some amino acids can be used by the liver to make glucose c) the carbon skeletons of glycogenic amino acids cannot be catabolized to make ATP d) the catabolism of amino acids produces ammonia, which is toxic

c) the carbon skeletons of glycogenic amino acids cannot be catabolized to make ATP

vigorous exercise is known to break down muscle proteins. What is the probable metabolic fate of the resulting free amino acids? a) the amino groups are removed and the nitrogens are eventually excreted in the form of urea b) the carbon skeletons can be completely catabolized to CO2 by muscle cells to produce ATP via the citric acid cycle and oxidative phosphorylation c) they can be partially broken down and transported to the liver to be used in gluconeogenesis d) all of the above e) none of the above

d) all of the above

Which of the following is TRUE in the liver after a meal rich in carbohydrates? a) oxaloacetate levels are high and citrate synthesis increases b) gluconeogenesis is activated and glycolysis is inhibited c) acetyl-coa levels rise and ketone body synthesis increases d) acetyl-coa levels fall and the rate of cholesterol synthesis decreases

a) oxaloacetate levels are high and citrate synthesis increases

which of the following occurs during the Cori cycle? a) NAD+ is regenerated in the liver by the conversion of pyruvate to lactate b) lactate is transported in the blood stream from the liver to the muscle c) lactate dehydrogenase activity is inhibited in the muscle d) lactate is converted to glucose, in the liver, via gluconeogenesis

d) lactate is converted to glucose, in the liver, via gluconeogenesis

Which of the following metabolic pathways occurs exclusively in the cytosol? a) citric acid cycle b) ketogenesis c) urea cycle d) amino acid degradation e) fatty acid synthesis

e) fatty acid synthesis

where are triacylglycerols stored in humans under normal conditions? a) adipocytes b) hepatocytes c) liver cells d) myocytes

a) adipocytes

Under anerobic conditions, _______ is produced in the muscle and is then used by the liver for ________

lactate; gluconeogenesis

In a well-fed state, brain cells use which one of the following compounds circulating in the blood stream almost exclusively as an energy source? a) insulin b) ketone bodies c) glucose d) fatty acids e) amino acids

c) glucose

the effect of epinephrine upon the liver is most similar to which of the following hormones? a) insulin b) glucagon c) leptin d) resistin e) ghrelin

b) glucagon

is hormone-sensitive lipase activated, inhibited or unaffected in response to a glucagon signal?

activated

adrenalin (epinephrine) is the "fight-or-flight hormone". one of its physiological roles is to mobilize fuel stores in preparation for activity. Given this, which of the following does NOT typically occur in response to the release of adrenalin? a) glycogen breakdown in the muscle b) glycogen synthesis in the liver c) gluconeogenesis in the liver d) glycolysis in the muscle

b) glycogen synthesis in the liver

in an attempt to lose weight, many people follow a high fat, high protein, low carbohydrate diet. which of the following substances would NOT have an increased concentration in the blood after two weeks on this diet? a) ketone bodies b) urea c) insulin d) amino acids e) fatty acids

c) insulin

for the following process, indicate whether is is activated (A) or inhibited (B) during FASTING. lipolysis in adipocytes

A. activated

what organelle is found in mulch higher amounts in brown adipose tissue than white adipose tissue? a) mitochondria b) lysosome c) endoplasmic reticulum d) chloroplast e) none of the above

a) mitochondria

insulin-dependent (type 1) diabetes _________. a) is associated with a deficiency of signal transduction b) can be treated with injections of leptin c) is associated with a deficiency of pancreatic B cells d) can be treated with injections of ghrelin e) is associated with a deficiency of insulin receptors

c) is associated with a deficiency of pancreatic B cells

What is it advantageous for cancer cells to uptake large quantities of glutamine? a) glutamine is needed for protein synthesis b) glutamine is a precursor for glutamate used in protein synthesis c) glutamine serves as a source of nitrogen atoms in nucleotide synthesis d) high glutamine levels can increase flux through the citric acid cycle e) all of the above

e) all of the above