《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