2010 Fall Bio 317 Exam 1

2010 Fall Bio 317 Exam 1 - BIO317Exam1 October5,2010 1)

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Unformatted text preview: BIO317Exam1 October5,2010 1) Assumeyouarerecordingthemembranepotentialinanormalaxonandtheplasmamembraneis permeabletoNa+andK+only.Whenthemembranepotentialisstableatrestinglevel(i.e.,noaction potentials), a) iK+iNa=0. b) iK+iNa<0. c) iK+iNa>0. d) iK=iNa=0. 2) Assumeyouarerecordingthemembranepotentialinanormalcellandtheplasmamembraneis permeabletoK+andNa+.WithrespecttothemovementofKandNaacrosstheplasmamembrane, hyperpolarizingthecellfrom70mVto80mVwill a) increaseKeffluxanddecreaseNaefflux. b) decreaseKeffluxanddecreaseNainflux. c) decreaseKeffluxandincreaseNainflux. d) notchangetheinflux/effluxofKandNa. 3) Whichofthefollowingisnotasignificantfactorindeterminingmembranepermeability? a) Ionchannelconductance b) Theprobabilitythatindividualionchannelsareopen c) Ionchanneldensityintheplasmamembrane d) Ionelectrochemicalgradient 4) Whichofthefollowingpropertyofphospholipidsisimportantwithrespecttomembranefluidity? a) Phospholipidsspontaneouslyformbilayersinanaqueoussolution. b) Phospholipidsbilayersspontaneouslyclosetoformsealedcompartments. c) Phospholipidbilayershaveaselfhealingproperty. d) Thefattyacidtailsinphospholipidsfrequentlyhavecisdoublebonds 5) Withrespecttotransportofhydrophilicsubstancesthroughtheplasmamembrane,whichofthe followingisalwaystrueforactivetransportandalwaysfalseforpassivetransport? a) involvestransmembranecarrierproteins b) cannotmoveasubstanceagainstaconcentrationgradient c) coupledtoadirectsourceofenergy(e.g.,ATPhydrolysis) d) highlyselective 6) Whichofthefollowingstatementsiscorrect? a) Glycolipidsarelocatedprimarilyinthecytosolicleafletoftheplasmamembrane. b) Increasingthedensityofcholesterolmoleculesintheplasmamembraneincreasesthefluidityof thelipidbilayer. c) Theasymmetryoftheplasmamembraneindueinparttotheinabilityofphospholipidmolecules todiffuselaterallyinthemembrane. d) Thelipidbilayerisaneffectivebarriertothediffusionofallions. page1 BIO317Exam1 October5,2010 7) Whichofthefollowingstatementaboutaminoacids/proteinsiscorrect? a) Allaminoacidswithunchargedsidechainsarehydrophobic. b) Foraproteininafoldedconformationinanaqueousenvironment,mostoftheaminoacidswith nonpolarsidechainswillbelocatedinthecoreofthemolecule. c) Theangleofthepeptidebondbetweenaminoacidsinaproteinisflexibleandchangesduring proteinfolding. d) Anhelixisarigidproteinstructuremaintainedbyhydrogenbondsbetweenhydrophobic aminoacidsidechains. 8) Compartments 1 & 2 above are separated by a membrane that is equally permeable to Na+ and Cl-. .Assuming the concentrations given above, which of the following do you expect will happen? a) Na+ and Cl- will both diffuse down their concentration gradients but no potential will develop across the membrane because the charges balance. b) Neither Na+ nor Cl- will diffuse across the membrane because they have equal and opposite charges. No potential difference will develop across the membrane. c) Na+ and Cl- will both diffuse down their concentration gradients and an electrical potential quickly develops across the membrane such that E2<E1. However, this potential decreases to zero over time. d) Diffusion of Na+ creates a stable electrical potential across the membrane that continues indefinitely. 9) InEquineHyperkalemicPeriodicParalysis, a) amutationintheNaV1.4channelproducesdefectiveinactivationandsustainedinward(i.e., negative)current b) amutationintheKV5.1channelproducesadecreaseinoutward(i.e.,positive)currentand sustaineddepolarization. c) amutationintheskeletalmuscleNa+channelproducesanincreaseintheabsoluterefractory periodleadingtohyperpolarizationandparalysis. d) amutationinthecardiacNa+channelproducesanincreaseinthedurationoftheventricular actionpotentialandincreasedexcitability. page2 BIO317Exam1 October5,2010 10) In the model cell above, assume that the membrane is permeable to Na+, K+ and Cl- and that the membrane potential is -70 mV. Which of the following statements is incorrect? a) Increasing [Na+]out to 150 mM would cause the cell to depolarize. b) Increasing [K+]out to 15 mM would cause the cell to depolarize. c) Increasing [Cl-]out to 150 mM would cause the cell to hyperpolarize. d) Decreasing [K+]in to 100 mM would cause the cell to depolarize. 11) TheslowlyinactivatingvoltagegatedCa++channelsfoundinmostsecretorycellsare a) TtypeCa++channels b) LtypeCa++channels c) NtypeCa++channels d) P/QtypeCa++channels 12) WhichofthefollowingfunctionsofK+channelsinexcitablecellscouldbeduetoKirchannelsbutnot HCNchannels? a) StabilizeEM b) Keepactionpotentialsshortinduration c) Terminateperiodsofintenseneuronalactivity d) Timeinterspikeintervalsduringrepetitiveactivity 13) Forahypotheticcell,assume(1)theplasmamembraneispermeableonlytoNa+andK+, (2)PNa/PK=0.02,and(3)theconcentrationsofNa+andK+are: [K]out=100mM;[K]in=10mM;[Na]out=5mM;[Na]in=120mM Themembranepotentialofthecellisapproximately, a) 58mV b) 70mV c) 10mV d) 45mV page3 BIO317Exam1 October5,2010 14) Inahypotheticalcell,theequilibriumpotentialsforionicspeciesare: ENa=30mV,EK=+40mV,ECa=60mV. IfthemembraneispermeabletoNa,thenthemembranepotentialcannotbe a) 60mV b) 30mV c) 0mV d) 30mV 15) Intheexperimentillustratedabove,thevoltageclamptechniquewasusedtostudyioniccurrentsin thegiantaxonofthesquid.Thecontrolrecordsontheleftwereobtainedundernormalconditions andtherecordsontherightwereobtainedafterapplying, a) 4Aminopyridine b) Saxitoxin c) Tetraethylammonium d) Proteolyticenzyme(totheinsideoftheaxon) 16) Inmanyneuronsduringdevelopment,thechlorideequilibriumpotentialismorepositivethanthe restingmembranepotential.Intheseneurons,theopeningofchloridechannelsleadsto: a) Anincreaseininward(negative)currentandhyperpolarization. b) Anincreaseinoutward(positive)currentandhyperpolarization. c) Anincreaseininward(negative)currentanddepolarization. d) Anincreaseinoutward(positive)currentanddepolarization. 17) Whichofthefollowingstatementsistrueformyelinatedaxonsbutnottrueforunmyelinatedaxons? a) Actionpotentialpropagationoccursinacontinuousfashionalongthelengthoftheaxon. b) Actionpotentialconductionvelocityishigherinlargediameteraxonsthaninsmalldiameter axons. c) Voltagegatedsodiumandpotassiumchannelsarelocalizedtospecificregionsintheaxon membrane. d) Axondepolarizationleadstothegenerationofanallornoneactionpotential. page4 BIO317Exam1 October5,2010 18) Whatisthedifferencebetweenchemicalandelectricaltransmission? a) Theyarebothmediatedbythesameneurotransmitterbuthavedifferentreceptors b) Theformerismediatedbyneurotransmitterrelease;thelatterdependsontheflowofions throughspecializedportionsofthemembrane c) Theyaremediatedbydifferentneurotransmittersandreceptors d) Electricalsynapsesarenotpresentinneurons 19) Whatisspatialsummation? a) Aseriesofactionpotentialsfromasingleaxonthatincreasesthedepolarizationinthe postsynapticneuron b) Multiplesynapticresponsesfromasingleactionpotential c) Thecombinationofmultipleinputsfromdifferenttypesofneurons d) Asinglesynapticresponsetoasingleactionpotential 20) Whatarethepropertiesoflongtermpotentiation? a) Itisneverinducedifpresynapticandpostsynapticneuronsareactiveatthesametime b) ItisinducedbytheactivationofGABAreceptors c) Coincidence,specificityandassociativity d) Itdependsonpotassiumchannels 21) WhyareGABAreceptorsinhibitory? a) Theyarenotveryefficientatbindingneurotransmitters b) Theirporeopensonlywhenthemembraneishyperpolarized c) Theyflownegativechargesintotheneuronandlowerthemembranepotential d) TheyactivateGproteinsthatcloseporesflowingpositivecharges 22) Whatisametabotropicreceptor? a) Areceptorwhichcontainsanionchannel b) Areceptorthatbindstheneurotransmitterandleadstotheopeningofavoltagegatedionchannel viaacoupledGprotein c) Aproteinthatisundertheneuronalmembraneandisactivatedbyactionpotentials d) Theyareactivatedbycalciuminfluxandmediateneurotransmitterrelease 23) LambertEatonMyastenicSyndromecausemuscleweaknessby: a) DisruptionofpresynapticactivezonesanddecreaseinthenumberofCa2+channelsthatleadto decreasedneurotransmissionattheneuromuscularjunction b) Lossofsynapsesbetweenmotorneuronsandmusclecells c) Hyperpolarizationofthemusclecell d) DecreaseofthenumberofAcetylcholinemoleculesinthepresynapticvescicles page5 BIO317Exam1 October5,2010 24) The5eventsofneurotransmitterreleaseare(inthecorrectorder): a) 1calciumionsactivatethedockingandfusionmachineryattachedtovesiclesof neurotransmitter;2theactionpotentialinvadesthepresynapticterminal;3themoleculesof neurotransmitterarereleasedinthesynapticcleft;4calciumionsflowthroughvoltagegated calciumchannels;5themembraneofthevesiclesfuseswiththepresynapticmembrane b) 1theactionpotentialinvadesthepresynapticterminal;2calciumionsflowthroughvoltagegated calciumchannels;3calciumionsactivatethedockingandfusionmachineryattachedtovesiclesof neurotransmitter;4themembraneofthevesiclesfuseswiththepresynapticmembrane;5the moleculesofneurotransmitterarereleasedinthesynapticcleft c) 1calciumionsactivatethedockingandfusionmachineryattachedtovesiclesof neurotransmitter;2theactionpotentialinvadesthepresynapticterminal;3themoleculesof neurotransmitterarereleasedinthesynapticcleft;4calciumionsflowthroughvoltagegated calciumchannels;5theneurotransmitterentersthepostsynapticneuron d) 1theactionpotentialinvadesthepresynapticterminal;2calciumionsflowthroughvoltagegated calciumchannels;3calciumionsactivatethedockingandfusionmachineryattachedtovesiclesof neurotransmitter;4theneurotransmitterflowsoutsideofthesynapticcleft;5themoleculesof neurotransmitterareuptakenbythepresynapticterminal 25) Whathappenstotheneurotransmittermoleculesaftertheyhavebeenreleased? a) Theybindtotheappropriatereceptor,thentheyunbindandbecomedegradedandrecycled b) Theyaredegradedrightawaysothattheycannotbindtoreceptors c) Theyenterthereceptorandmediatesecondmessengercascades d) Noneoftheabove page6 ...
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