生化英文习题

八年制复习资料一Question1.WhilestudyingthestructureofasmallgenethatwasrecentlysequencedduringtheHumanGenomeProject,aninvestigatornoticesthatonestrandoftheDNAmoleculecontains20A’s,25G’s,30C’s,and22T’s.Howmanyofeachbaseisfoundinthecompletedouble-strandedmolecule?A.A=40,G=50,C=60,T=44B.A=44,G=60,C=50,T=40C.A=45,G=45,C=52,T=52D.A=50,G=47,C=50,T=47E.A=42,G=55,C=55,T=422.ThebasesequenceofthestrandofDNAusedasthetemplatefortranscriptionhasthebasesequenceGATCTAC.WhatisthebasesequenceoftheRNAproduct?(Allsequencesarewrittenaccordingtostandardconvention.)A.CTAGATGB.GTAGATCC.GAUCUACD.CUAGAUGE.GUAGAUC3.Afour-year-oldchildwhobecomeseasilytiredandhastroublewalkingisdiagnosedwithDuchennemusculardystrophy,anX-linkedrecessivedisorder.Geneticanalysisshowsthatthepatient’sgeneforthemuscleproteindystrophincontainsamutationinitspromoterregion.Whatwouldbethemostlikelyeffectofthismutation?A.Initialtionofdystrophintranscriptionwillbedeficient.B.Terminationofdystrophintranscriptionwillbedeficient.C.CappingofdystrophinmRNAwillbedefective.D.SplicingofdystrophinmRNAwillbedefective.E.TailingofdystrophinmRNAwillbedefective.AnswerE.thetwoDNAstrandsarecomplementarytoeachother,withAbase-pairedwithT,andGbasepairedwithC.So,forexample,the20A’sonthefirststrandwouldbepairedwith20T’sonthesecondstrand,the25G’sonthefirststrandwouldbepairedwith25C’sonthesecondstrand,andsoforth.Whenthesearealladdedtogether,thecorrectnumbersofeachbaseareindicatedinchoiceG.Noticethat,inthecorrectanswer,A=TandG=CE.Allsequencesarewritteninthestandardconvention(5’-3’).TheRNAproducthasasequencethatiscomplementarytothesequenceofthetemplatestrandofDNA.Uracil(U)isfoundinRNAinplaceofthethymine(T)inDNA.Thus,theDNAtemplate5’-GATCTAC-3’wouldproducetheRNAproduct3’-CUAGAUG-5’or,writtencorrectlyinthestandarddirection,5’-GUAGAUC-3’.A.MutationsinthepromoterpreventformationoftheRNApolymeraseIItranscriptioncomplex,andtheinitationofmRNAsynthesiswillbegreatlydecreased.AdeficiencyofdystrophinmRNAwillresultinadeficiencyintheprocductionofthedystrophinprotein,Whichoneofthefollowingcorredtlypairsanaminoacidwithavalidchemicalcharacteristic?A.Glutamine:ContainsahydroxylgroupintissidechainB.Serine:CanformdisulfidebondsC.Cysteine:ContainsthesmallestsidechainD.Isoleucine:isnearlyalwaysfoundburiedinthecenterofproteinsE.Glycine:ContainsanamindegroupinitssidechainWhichoneofthefollowingstatementsconcerningglutamineiscorrect?A.ContainsthreetitratalbegroupsB.IsclassifiedasanacidicaminoacidC.ContainsanamidegroupD.HasEasitsone-lettersymbolE.Migratestothecathode(negativeelectrode)duringelectrophoresisatpH7.0Apeptidebond:A.hasapartialdouble-bondcharacter.B.isionizedatphysiologicpHC.iscleavedbyagentsthatdenatureproteins,suchasorganicsolventsanhighconcentrationsofureaD.isstaletoheatinginstrongacidsE.occursmostcommonlyinthecisconfiguration.Whichoneofthefollowingstatementsiscorrect?A.Theα-helixcanbecomposedofmorethanonepolypeptidechain.B.β-sheetsexistonlyintheantiparallelform.C.β-Bendsoftencontainproline.D.Motifsareatypeofsecondarystructure.E.Theα-helixisstabilizedprimarilybyionicinteractionsbetweenthesidechainsofaminoacids.D.Inproteinsfoundinaqueoussolutions,thesidechainsofthenonpolaraminoacids,suchisoleucine,tendtoclustertogetherintheinterioroftheprotein.Glutaminecontainsanamideinitssidechain.Serineandthreoninecontainahydroxylgroupintheirsidechain.Cysteinecanformdisulfidebonds.Glycinecontainsthesmallestsidechain.C.Glutaminecontainstwotitratablegroups,α-carboxylandα-amino.Glutamineisapolar,neutralaminoacidthatshowslittleelectrophoreticmigrationatpH7.0.Thesymbolforglutamineis“Q”.A.thepeptidebondhasapartialdouble-bondcharacter.Unlikeitscomponents–theα-aminoandα-carboxylgroups–thecomponentsofthepeptidebonddonotacceptorgiveoffprotons.Thepeptidebondisnotcleavedbyorganicsolventsorurea,butislabiletostrongacids.ItisusuallyinthetransconfigurationC.β-bendsoftencontainproline,whichprovidesakink.Theα-helixdiffersfromtheβ-sheetinthatitalwaysinvolvesthecoilingofasinglepolypeptidechain.Theβ-sheetoccursinbothparallelandantiparallelforms.Motifsareelementsoftertiarystructure.Theα-helixisstabilizedprimarilybyhydrogenbondsbetweenthe–C=Oand–NH-groupsofpeptidebonds.Whichoneofthefollowingstatementsaboutproteinstructureiscorrect?A.Proteinsconsistingofonepolypeptidecanhavequaternarystructure.B.Theformationofadisulfidebondinaproteinrequiresthatthetwoparticipatingcysteineresiduesbeadjacenttoeachotherintheprimarysequenceoftheprotein.C.Thestbilityofquaternarystructureinproteinsismainlyaresultofcovalentbondsamongthesubunits.D.thedenaturationofproteinsalwaysleadstoirreversiblelossofsecondaryandtertiarystructure.E.Theinformationrequiredforthecorrectfoldingofaproteiniscontainedinthespecificsequenceofaminoacidsalongthepolypeptidechain.An80-year-oldmanpresentedwithimpairmentofhigherintellecutualfunctionandalterationsinmoodandbehavior.Hisfamilyreprotedprogressivedisorientationandmemorylossoverthelastsixmonths.Thereisnofamilyhistoryofdementia.ThepatientwastentativelydiagnosedwithAlzeheimerdisease.Whichoneofthefollowingbestdescribesthedisease?A.Itisassociate