《基因工程》习题及参考答案.docx

《基因工程》习题及参考答案.docx

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《基因工程》习题及参考答案

《基因工程》习题及参考答案

一、习题：

1.Whatarebiotechnologyandgeneticengineering?

2.Whatisagene?

3.Whataregeneticallyengineeredmedicines?

4.Whatdogenomeresearchandhumangeneticsdealwith?

5.Whatpotentialsareheldoutbygeneticdiagnosis?

6.Whatoptionsaregivenbygenetherapy?

7.Whatisanembryo-andwhatisafetus?

8Whatisageneticfingerprint?

9Whatdoestheterm"therapeuticcloning"mean?

10Whatarestemcells?

11Whatisatransgenicorganism?

12Whatdoesxenotransplantationmean?

13Howwillgeneticengineeringbeusedinagriculture?

14Howaregeneticallymodifiedorganismsassessed?

15WhatdoestheGermanEmbryoProtectionActregulate?

16.Whatisagenome?

17.Isthereariskofbioterrorism?

18.Howdoesgeneticengineeringaffecttheenvironment?

19.Aregeneticallyengineeredcropsgoodforfarmers?

20.Whatisthedifferencebetweenrestrictiondigestionandrestrictionmapping?

21.CanyoucombinetwodifferentrestrictionenzymesinthesamereactiontubestodigesttheDNAmolecules?

22.Whyshouldweneedtogeneraterestrictionmappingdata?

23.Howmanyrestrictionenzymesavailablenowonthemarket?

24.Whydoyouconsidermutagenesisinvitroasoneofthemostcriticaltechniquesforustounderstandingeneticengineeringclass?

25.HowdowechoosethemethodsforDNAmodification?

26.Howdowechooseageneexpressionsystem?

27.HowcanweexpresseukaryoticgeneinE.coli?

28.Whatshouldweconsiderbeforewestarttherecombinantproteinexpressionexperiment?

29.Whatistheadvantageofyeastexpressionsystem?

30.Whatistheadvantageofinsectexpressionsystem?

31.Whytherearesomanydifferenttypesofvectorsavailableforcloning?

32.Whatisthedifferencebetweencloningvectorandexpressionvector?

33.Whatisageneticfingerprint?

34.基因具体分成多少种类？

35.什么叫印记基因？

36．什么叫遗传漂变？

37．人类基因组图谱和初步分析结果是在哪一年公布的？

38．人类基因组共有多少基因?

39.克隆羊成功的技术关键是什么？

40.有人计划将两个不同物种的动植物体细胞进行融合，然后将融合体的核移植到其中一种生物的未受精卵细胞中，进行体细胞克隆。

此计划可行吗？

为什么？

41.切口移位标记探针的主要步骤有哪些？

42.用EcoRⅠ和HindⅢ分别切割同一来源的染色体DNA，并进行克隆，在前者的克隆中筛选到A基因，但在后者的克隆中未筛选到A基因，是什么原因？

43.在基因工程中，为了在细菌细胞中表达真核细胞的基因产物，为什么通常要用cDNA而不用基因组DNA？

为什么要在cDNA前加上细菌的启动子？

44.当两种限制性内切酶的作用条件不同时，若要进行双酶切，应采取什么措施？

为什么？

45.有些噬菌体和质粒常常编码一些抗限制性酶的蛋白以中和宿主的限制系统。

除此之外噬菌体和质粒还有哪些可能的方式避免宿主的限制系统？

46.为什么大多数内切酶被称为“限制”酶？

47.何谓同裂酶？

48.什么是限制性物理图谱？

49.为什么反转录酶在聚合反应中会出错？

50.RNaseA和.RNaseH在催化活性和应用上有何不同？

51.切口移位标记DNA前，用DNaseⅠ处理DNA时，应注意什么？

52.DNA连接酶对DNA的复制是很重要的，但RNA的合成一般却不需要连接酶，为什么？

53.RNA聚合酶Ⅲ特异性地转录小分子RNA，但为什么不转录5.8SrRNA?

54.用EcoRⅠ切割外源DNA片段时出现了星号活性，可能是什么原因？

二、参考答案：

1Whatarebiotechnologyandgeneticengineering?

Biotechnologyisafieldofbioscience.Inverygeneraltermsitcanbedescribedasthetheoryoftheuseofbiologicalsystemsinresearchandapplications.Biotechnologyapplicationsarearapidlygrowingsectoroftheeconomy.ThenumberofbiotechcompaniesinGermanyhasincreasedconsiderablyoverthepastsevenyears.

Geneticengineeringincludesallbiotechnologicalprocessesaimedateffectingspecificchangesinthegeneticmaterialofcells.Theprincipleis,ingeneral,thefollowing:

sectionsofDNA（=deoxyribonucleicacid）fromoutsidesourcesareintroducedintoacellinordertobringaboutdefinedchanges.Whatisinvolvedinmostcasesisthesynthesisofmolecules,theinformationforwhichiscontainedintheintroducedDNA.Thisprocesshasbeenusedtoproducenewmedicines（seegeneticallyengineeredmedicines）.

2Whatisagene?

Ageneisthesmallestunitofgeneticmaterial.ItdescribesaspecificsectionofDNAwhich,asaresultofitsnucleotide（=DNAcomponent）sequence,determinesspecificfunctions,characteristics,features,orstructuresofacell.Thewaygenesareexpressedineachcaseisdependentontheirinteractionwithothergenesandwiththeenvironment.

Thegenomeistheentiretyofgenescontainedinanorganism.Thetermissynonymouswithgeneticmaterial.

3Whataregeneticallyengineeredmedicines?

Inthegeneticengineeringofmedicinesgenescontainingthecodesoftherapeuticallyvaluablesubstancesaretransferredtoeasilycultivatedcells.Inmostcasesbacteriaareused,morerarelyalsoyeastcellsandthecellsofmammals.Medicinesproducedinthiswayarecalledrecombinantmedicines.

Thehumaninsulinintroduced（fordiabetics）in1982wasthefirstrecombinantmedicine.Sincethemid-1990spersonswithhemophiliaA（themostcommonformofthisblooddisease）havebeentreatedtoanincreasingextentwithrecombinantfactorVIII.PriortothattheonlytreatmentavailablewasfactorVIIIproducedfromhumanplasma.

4Whatdogenomeresearchandhumangeneticsdealwith?

Genomeresearchpursuestheobjectiveofidentifyingthestructuresandfunctionsoftheindividualgenesinthegenome.Theobjectofgenomeresearchisthestudyofthegeneticmaterialofallorganisms,meaningthatthegenomesofcertainplants,animals,andmicroorganismsarejustasmuchasubjectofstudyasthehumangenome.

Itisanimportanttaskofhumangenomeresearchtoidentifywhatgenesareinvolvedandinwhatwaystheyareinvolvedincausingdiseases.Thisresearchisexpectedtobringnewapproachesinthetreatmentofcardiovasculardiseases,cancer,infectiousdiseases,anddiseasesofthecentralnervoussystemsuchasParkinson'sdisease,multiplesclerosis,orAlzheimer'sdisease.

ScientistspresentedthelargelydecodedhumangenomeonJune26,2000.Bothscientistsandgovernmentleadersthroughouttheworldnotedthisasanepoch-makingeventandanimportantmilestoneinthehistoryofmankind.Atthesametimethishascreatednewchallengesforscience,government,andethics.Thefieldofethicsiscalledupontoshowwhetherandhowthisknowledgecanbeusedresponsiblyinsuchwidelydiversefieldsasmedicineandagriculture.

Humangeneticsisamedicaldisciplinethatdealswithhumanheredity,thecausesanddiagnosisofhereditarydiseases,andthesearchforpossibletherapies.Diagnosticprocedurestodayincludestate-of-the-artgeneticdiagnosesinadditiontotraditionalanalysesofhereditarymechanisms.

5Whatpotentialsareheldoutbygeneticdiagnosis?

Moderngeneticdiagnosismethodsmakeitpossibletoanalyzeindividualstructuresofthegenomeand,indoingso,toidentifygenedefectsassociatedwithhereditarydiseasessuchascysticfibrosis.Thiswouldbebeneficialtopersonswhocarrythegeneandwouldruntheriskofpassingitontotheirchildren.Itisconceivablethatawarenessofaninheritedpredispositionforadiseasethatemergeslaterinlifewouldcausethepersonsinquestiontotakespecialprecautionssuchasgoinginforpreventivecheckupsorpursuingalifestyleaimedatpreventinganoutbreakofthedisease.

Genetestscanbeusedtoconfirmthediagnosisofsuspecteddiseases.Morethanthat,modernmethods（suchasgenechips）canbeusedtohelpawiderangeofpeople,includingthosewhoarenotsick,toidentifygeneticcharacteristicssuchaspredispositionsforcertaindiseases.Here,entirelynewethicalandlegalquestionsarearisingforsociety.Inthecaseofpredictivegenetests,i.e.testsusedtomakeforecastsastorisksofhereditaryillness,itwillbeaseparatetasktodeterminewhetherthesetestswillbeofvaluetoindividualsandtosocietyasawhole.

Weneedtodistinguishbetweenpreimplantationgeneticdiagnosis（PGD）,prenatalgeneticdiagnosisinthecontextofprenatalcare,andpostnatalgeneticdiagnosis.

Preimplantationgeneticdiagnosis（PGD）isacontroversialareaofgeneticdiagnosis.AfterinvitrofertilizationPGDcanbeusedtocarryoutagenetestonanembryobeforeitisimplantedinthemother'suterus.Bythismeansembryosshowingaspecificgeneticdefectcanbesortedout.

6Whatoptionsaregivenbygenetherapy?

Theobjectiveofgenetherapyistotreatorpreventdiseases,makinguseofgeneticengineeringprinciples.DNAcan,forinstance,beintroducedintobloodorlivercellsbymeansofvectorsinordertoeliminategeneticdefectspresentthere.Orcellsthathavebeengeneticallymodifiedoutsideofthebodymaybeimplantedinthepatient.Afurtherapproachistheinjectionofso-callednakedDNAasakindofvaccine.NakedDNAmakesitpossibletosynthesizeproteinsagainstwhichthevaccinatedpersonbuildsupanimmunereactionasinthecaseofaconventionalvaccination,exceptthathereamuchmorespecificallytargetedeffectontheimmunesystemisexpected.

Somaticgenetherapymustbedistinguishedfromgermlinegenetherapy.Aftergermlinegenetherapytheeffectedchangeingeneticinformationwouldbepassedontotheoffspringoftheindividualinquestion.Theprerequisiteforthiswouldbemanipulationofthegeneticmaterialcontainedinaneggcelloraspermcellorofthegeneticmaterialcontainedinanembryointheearlystagesofdevelopment.TheGermanEmbryoProtectionActimposesacomprehensivebanoncarryingoutgermlinegenetherapyinhumans.

Inthecaseofsomaticgenetherapy（=therapyoforinvolvingbodycells）onlybodycells（=somaticcells）aretheobjectofchange.Sincethistypeoftreatmentisdirectedexclusivelyatsomaticcells,itwillnothaveaneffectonthegeneticmaterialpassedontothepatient'soffspring.Thepredispositionforagivendiseasewillbepassedontothepatient'schildrenevenifgenetherapyissuccessful.Itshouldbenotedthatatthepresenttimegenetherapyisusedmostlytotreatmalignantcancers,andinGermanyexclusivelyinsuchcases.Thecauseofthediseaseisusuallynotassociatedwithonesinglegenebutratherwithacombinationofexternalfactorsinvolvingseveralgenes.Forpartofthediseasestreatedthereisnoevidenceofageneticpredispositionandintheunderlyingtherapeu