廈門大學(xué)細(xì)胞生物學(xué)2019年期末考試試題

廈門大學(xué)細(xì)胞生物學(xué)課程試卷___________學(xué)院______系__2019__年級_______專業(yè)1.Glossary(20)

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試卷類型：（A卷）1) SH2andSH3domain(4)2) Treadmilling(4)3) PullandPushhypothesis(4)4) NLS(4)5) Phosphorylationcascades(4)2.HowdoMTpolymerize?Describethisprocessandthenecessarycomponents(12)3.Howcanp21,p53,cdc25,andRbleadtoarrestofthecellcycle?(12)4.Summarizetheprocessofubiquitylation?Howdoesubiquitylationaffectcellcycle?(12)5.Distinguishbetweensynaptic,paracrine,andendocrinemechanismsofcellsignaling.(12)6.CompareanaphaseAandanaphaseB.（10）7.Describethemechanismofskeletalmusclecontraction.（12）8.Describethetwobranchesoftheinositolphospholipidpathway （10）1.Glossary(20)1) SH2andSH3domain(4)A:Srchomologydomain(SH2)thatmbindtophosphorylatedtyrosinesinaparticularpeptidesequenceonactivatedreceptorsorintracellularsignalingproteins.SH3bindtoashortproline-richaminoacidsequence.2) Treadmilling(4):A:WhentheconcentrationoffreemonomerisaboveCcfortheplusendbutbelowCcfortheminusend,thepolymermaintainsaconstantlength,eventhoughthereisanetfluxofsubunitsthroughthepolymer.3) PullandPushhypothesis(4):A:TwohypothesesforhowchromosomeslineupatthemetaphaseplatePullhypothesis:PullingforceproportionaltolengthofkinetochoremicrotubulesPushhypothesis:Astralexclusionforcedecreaseswithdistancefrompole4) NLS(4)A:AbbreviationofNuclearLocalizationSignals,polypeptidethatdirectNuclearProteinstotheNucleus,suchaslys-lys-lys-arg-lys.5) Phosphorylationcascades(4)A:Oneproteinkinase,activatedbyphosphorylation,phosphorylatesthenextproteinkinaseinthesequence,andsoon,relayingthesignalonwardand,intheprocess,amplifyingitandsometimesspreadingittoothersignalingpathways.2.HowdoMTpolymerize?Describethisprocessandthenecessarycomponents(12)A:Microtubulesaregenerallynucleatedfromaspecificintracellularlocationknownasamicrotubule-organizingcenter(MTOC).ThecentrosomeisthemajorMTOCofanimalcells.Locatedinthecytoplasmnexttothenucleus,itconsistsofanamorphousmatrixofproteincontainingthe γ-tubulinringcomplexesthatnucleatemicrotubulegrowth.Thismatrixisorganizedbyapairofcentrioles.Acentrosomeisattachedbymicrotubules.Theminusendofeachmicrotubuleisembeddedinthecentrosome,havinggrownfroma γ-tubulinringcomplex,whereastheplusendofeachmicrotubuleisfreeinthecytoplasm.Duringthisprocessmanyproteinsacttomeditatethepolymerization,includingstathmin,whichcausethedepolymerizationofMT,andMAP,whichhelpstopolymerizeandATP-requiredkatanin,whichseversmicrotubule.3.Howcanp21,p53,cdc25,andRbleadtoarrestofthecellcycle?(12)A:DNAdamageleadstotheactivationofthegeneregulatoryproteinp53,whichstimulatesthetranscriptionofseveralgenesincludingaCKIproteincalledp21,whichbindstoG1/S-CdkandS-Cdkandinhibitstheiractivities,therebyhelpingtoblockentryintoSphase.WhencellsinG2areexposedtodamagingradiation,forexample,thedamagedDNAsendsasignaltoaseriesofproteinkinasesthatphosphorylateandinactivatethephosphataseCdc25.ThisblocksthedephosphorylationandactivationofM-Cdk,therebyblockingentryintomitosis.G1-Cdkactivity(cyclinD-Cdk4)initiatesRbphosphorylation.ThisinactivatesRb,freeingE2FtoactivatethetranscriptionofS-phasegenes,includingthegenesforaG1/S-cyclin(cyclinE)andS-cyclin(cyclinA).TheresultingappearanceofG1/S-CdkandS-CdkactivitiesfurtherenhancesRbphosphorylation,formingapositivefeedbackloop.4.Summarizetheprocessofubiquitylation?Howdoesubiquitylationaffectcellcycle?(12)A:TheC-terminusofubiquitinisinitiallyactivatedthroughitshigh-energythioesterlinkagetoacysteinesidechainontheE1protein.TheactivatedubiquitinonE1,alsoknownastheubiquitin-activatingenzyme,isthentransferredtothecysteinesonasetofE2molecules.TheseE2sexistascomplexeswithanevenlargerfamilyofE3molecules.Theadditionofamultiubiquitinchaintoatargetprotein.TheE2arecalledubiquitin-conjugatingenzymes.TheE3havebeenreferredtotraditionallyasubiquitinligases.SCFandAPC(Anaphase-promotingcomplex)servesasaubiquitinligase(E3)thattransfersmultipleubiquitinmoleculesontothetargetprotein,isresponsiblefortheubiquitylationanddestructionofG1/S-cyclinsandcertainCKIproteinsthatcontrolS-phaseinitiationandM-cyclinsandotherregulatorsofmitosisinMphase,respectively.5.Distinguishbetweensynaptic,paracrine,andendocrinemechanismsofcellsignaling.(12)A:synapticsignaling:Typeofcell–cellcommunicationthatoccursacrosschemicalsynapsesinthenervoussystem.Paracrinesignaling:Short-rangecell-cellcommunicationviasecretedsignalmoleculesthatactonadjacentcells.Endocrinecellsignaling:Specializedanimalcellthatsecretesahormoneintotheblood.Usuallypartofagland,suchasthethyroidorpituitarygland.6.CompareanaphaseAandanaphaseB.（10）A:AnaphaseA:thedaughterchromosomesmovetowardsthenearestpole,thecellelongationdoesnotoccur.AnaphaseB:thetwospindlepolesmoveapart,cellelongationoccurs.Drive:AnaphaseA:dependsonmotorproteinsoperatingatthekinetochores,togetherwithKinetochoremicrotubulesdisassembleatbothendsAnaphaseB:Bothpullingandpushingforcesexertedonthisprocess.Pushingforceisgeneratedbetweenoverlapmicrotubuleswithplus-end-directedmotorproteinsandelongationofmicrotubules,pullingforceisgeneratedbetweenastralmicrotubulesandcellcortexwithminus-end-directedmotorproteins.7.Describethemechanismofskeletalmusclecontraction.（12）A:skeletalmuscleconsistsofadjacentmusclecellsthateachcontainsmyofibrilsandeachmyofibrilconsistesofachainofsarcomeres.sarcomereiscomposedofactinsandmyosinsandmanyotherassociatedproteins,itincludesAbandwhichconsistofbothmyosinandactin,Ibandwhichconsistofactinsonly,andHzone.EachendofsarcomereiscappedZdisc.Whenmusclecellsreceivesignalsformnerve,sarcoplasmicreticulumreleasealargeCa2+whichthenbindtotroponinstotorelievethetropomyosinblockageoftheinteractionbetweenactinandthemyosinhead.causingtheslidingbetweenthethinfilamentsandmyosin.8.Describe