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1答案4一、填空题(每空0.5分，共10分)1.寡聚糖，内质网，高尔基体，出芽，蛋白包被小泡，笼形蛋白包被小泡，调节型，包被蛋白复合体，组成型，辅基蛋白B-100，受体介导的内吞作用2.START3.螺线管压缩成超螺线管，40倍。4.基因调节作用5①铁硫蛋白；②辅酶Q；③黄素蛋白；④细胞色素。二、判断题(正确的标T，错误的标F,或写出必要的答案，共15分)1.Answer:(a)S;(b)M;(c)M;(d)G1;(e)M;(f)Gl;(g)Gl,G2,S;``(h)M,G2,S;(i)Gl,S,G2,M;(j)Gl,G2,M2.答：T,正确。3.答：错误,粉末状的染色体4.答：T,正确。5.答：F,错误，核纤层蛋白B与内核膜相连。6答：F,错误，被阻止在M期。7.答：不正确，因为二者的膜蛋白不同。8.答：正确。9.答：错误,8个小亚基是核基因编码;10.答：错误,给胞质分裂传递信号11.答:错误,同源染色体间的分子重组是随机发生的。三、选择题(请将正确答案的代号填入括号，每题1分，共15分)1.b2.d3b4.c5.b6.D7.a8.a9.D10.D11.C12.d13.d14.d15.a四、简答题(选做4题，每题5分，20分)1.Answer.Regulatedsecretionoccursonlyinresponsetoasignal.Theproteinstobesecretedarestoredinspecialsecretoryvesicles.Sortingintotheregulatedsecretorypathwayiscontrolledbyselectiveproteinaggregation.Constitutivesecretionappearstooccurbydefaultwithsecretoryproteins,whichdonotselectivelyaggregatebeingincludedintransportvesicles.2.Answer：IfGTPispresentbutcannotbehydrolyzed,microtubuleswillcontinuetogrowuntilallfreetubulinsubunitshavebeenusedup.3.Answer:Thecentrosomeservesasamicrotubule-organizingcenterinvivo,andallofthemicrotubulesradiatingfromthecentrosomeapparentlyhavethesamepolarity.4.答：加在于粗面内质网上合成的蛋白质上的糖基可由两种途径连接：通过天冬氨酸残基的N原子或通过丝氨酸和苏氨酸残基的O原子。N-连结糖蛋白合成的第一步在粗面内质网上进行，糖链是从磷酸多萜醇转移至新生肽链上。这种糖基化在高尔基体中继续被修饰。O-连结的糖基化是在高尔基体中进行的。5.答:过氧化物酶体中的氧化酶都是利用分子氧作为氧化剂,催化下面的化学反应:RH2+O2---------→R+H2O2这一反应对细胞内氧的水平有很大的影响。例如在肝细胞中,有20%的氧是由过氧化物酶体消耗的,其余的在线粒2体中消耗。在过氧化物酶体中氧化产生的能量以产热的方式消耗掉,而在线粒体中氧化产生的能量贮存在ATP中。线粒体与过氧化物酶体对氧的敏感性是不一样的,线粒体氧化所需的最佳氧浓度为2%左右,增加氧浓度,并不提高线粒体的氧化能力。过氧化物酶体与线粒体不同,它的氧化率是随氧张力增强而成正比地提高(图7-44)。因此,在低浓度氧的条件下,线粒体利用氧的能力比过氧化物酶体强,但在高浓度氧的情况下,过氧化物酶体的氧化反应占主导地位,这种特性使过氧化物酶体具有使细胞免受高浓度氧的毒性作用。五、计算与推理(第1题必做，2、3选一题，每题5分，共10分)1.Answer：Therearesixnucleosomesperhelicalturnofthesolenoidstructure,andonehelicalturnofthesolenoidcorrespondstoslightlylessthan30nmalongthelengthofachromatinthickfiber.Assuming,forsimplicityofcalculation,onehelicalturnper30nm,thenthereare6nucleosomesper30-nmstretchofthickfiber.A900-nm-long,thickfiberthushas30solenoidturns(900nmdividedby30nm/turn)andcontains180nucleosomes(6nucleosomes/turn×30turns).TheDNAcontentofeachhumannucleosomeplusthelinkerDNAconnectingittoadjacentnucleosomesisabout200bp.Thisthickfiberthuscontains36,000bpofDNA:(200bp/nucleosome)×(180nucleosomes/900-nmthickfiber).2.Answer：LossofcyclinleadstoinactivationofthemitoticCdk.Astheresult,itstargetproteinsbecomedephosphorylatedbyphosphatases,andthecellsexitmitosis--theydisassemblethemitoticspindle,reassemblethenuclearenvelope,decondensetheirchromosomes,andsoon.Cyclinisdegradedbyubiq-uitin-dependentdestructioninproteosomes,andtheactivationofthemitoticCdkmostlikelycausestheubiquitinationofthecyclin,butwithasubstantialdelay.AsdiscussedinChapter5,ubiquitinationtagsproteinsfordegradationinproteasomes.3.Answer：Theactualexplanationisthatthesingleaminoacidchangecausestheproteintomisfoldslightlysothat,althoughitisstillactiveasapro-teaseinhibitor,itispreventedbychaperoneproteinsintheERfromexitingthisorganelle.ItthereforeaccumulatesintheERlumenandiseventuallydegraded.Alternativeinterpretationsmighthavebeen:(1)themutationaffectsthestabilityoftheproteininthebloodstreamsothatitisdegradedmuchfasterinthebloodthanthenormalprotein,or(2)themutationinactivatestheERsignalsequenceandpreventstheproteinfromenteringtheER.(3)AnotherexplanationcouldhavebeenthatthemutationalteredthesequencetocreateanERretentionsignal,whichwouldhaveretainedthemutantproteinintheER.Onecoulddistinguishbetweenthesepossibilitiesbyusingfluorescent-taggedantibodiesagainsttheproteintofollowitstransportinthecells(seePanel5-3,pp.158-159).六、比较题（每题5分，共10分）1.Answer:BothdyneinandkinesinarelargemotorproteinsthatconvertthechemicalenergyofATPintomovement.Botharefoundaffiliatedwithmicrotubules,althoughonlydyneinoccursonthemicrotubulesofciliaandflagella.Kinesinisaplus-enddirectedmicrotubularmotor,anddynein,amongitsotherroles,isaminus-enddirectedmicrotubularmotor.Inspiteoftheirsimilaritiesinfunction,theyarenothomologousproteins,andtheyassumequitedifferentthree-dimensionalshapes.Theyarenotmembersoraproteinfamily.2.后期A与后期B七、综合问答题(任选一题，20分)1.答：翻译后转运与共翻译转运3跨膜运输小泡运输核孔运输2.答：同：有关卡，有周期蛋白与周期蛋白激酶；异：CDC2,CDC28,哺乳动物不同的激酶与多种周期蛋白。八、附加题（每题5分，共15分）1.Answer:Theextractsappeartocontainstructuresthatarefunctionallyequivalenttocentrosomes(asevidencedbythepresenceofpericentrin),whichnucleatemicrotubulegrowth.2.Answer:ThefunctionsofSRPweredemonstratedinaseriesofexperimentsutilizingacell-freeprotein-synthesizingsystemandmRNAencodingpre-prolactin,atypicalsecretoryprotein.WhenthemRNAwasincubatedinthecell-freetranslationalsystemintheabsenceofSRPandmicrosomes,thecompleteproteinwithitssignalsequencewasproduced.TheadditionofSRPtotheincubationmixturescausedproteinelongationtoceaseafter70-100aminoacidshadbeenincorporated.WhenmicrosomescontainingtheSRPreceptoralsowereaddedtotheincubations,theblockinproteinsynthesiswasrelievedandthecompleteproteinminusthesignalsequencewasextrudedintothelumenofthemicrosomes.3.Answer:DephosphorylationeventsduringmitosisincludeproteinphosphatasesremovingtheregulatoryphosphatesfromlaminsA,B,andC,permittingreassemblyo