遗传学chapter13chromosomal rearrangements and changes in单击此处编辑母版标题

Chapter13ChromosomalRearrangementsandChangesinChromosomeNumberCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-1OutlineofChapter13RearrangementsofDNAsequenceswithinand?betweenchromosomesDeletions?Duplications?Inversions?Translocations?Movementsoftransposableelements?Changesinchromosomenumber?Monoploidy?Polyploidy?Aneuploidy?Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-2TwotypesofeventsthatreshapegenomesChromosomalrearrangements?RearrangementsofDNAsequenceswithinoneormore?chromosomes.Changesinchromosomenumber?Lossesorgainsofchromosomesorsetsofchromosomes.?Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-3ChromosomalrearrangementsTable13.1Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-4DeletionsremovematerialfromthegenomeFig.13.2aCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-5DeletionsmayhavephenotypicconsequencesHomozygosityfora?deletionisoften,butnotalways,lethal.Heterozygosityfora?deletionisoftendetrimental.Evensmalldeletionscanbeharmful.Changeingenedosage?createsgeneticimbalance.Fig.13.3Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-6Deletionsinheterozygotescan“uncover”genesPseudodominance–Adeletionuncoversthe?phenotypeofarecessivemutation.Drosophilast/Delmutant(st:scarleteyecolor,recessive)Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-7Fig.13.5PolytenechromosomesinDrosophilasalivaryglandscanbeusedtomapdeletionsInterphasechromosomes?replicate10times.Eachchromosomeconsists?of210(1024)doublehelices.Reproduciblebands?providedetailedphysicalguidetogenemapping.Totalofabout5000bands?rangingfrom3kbto150kb.Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-8?DrosophiladeletionheterozygotesformvisibledeletionloopsinthepairedpolytenechromosomesCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-9DeletionscanbeusedtolocategenesDeletionstoassign?genestobandsonDrosophilapolytenechromosomes.Complementation?testscrossingdeletionmutantswithmutantgenesofinterests.Deletion?heterozygoterevealschromosomallocationofmutantgene.Drosophilawhite(w+),roughest(rst+),andfacet(fa+)genesontheXchromosomeCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-10Fig.13.8DuplicationsaddmaterialtothegenomeFig.13.11Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-11DuplicationscanaffectphenotypeNovelphenotypes?Moregenecopies.?Genesnextto?duplicationdisplacedtonewenvironmentalteringexpression.DrosophilaTriplolethal(Tpl+)locusFig.13.12Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-12UnequalcrossingoverbetweenduplicationsincreasesordecreasesgenecopynumberCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-13Fig.13.13InversionsreorganizetheDNAsequenceofachromosomeProducedbyhalf?rotationofchromosomalregionsafterdouble-strandedbreak.Alsobyrarecrossover?betweenrelatedgenesinoppositeorientationortransposition.Fig.13.14abCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-14AninversioncanaffectphenotypeifitdisruptsageneDrosophilayellow(y+)geneFig.13.14cCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-15Inversionheterozygotesproducefew,ifany,recombinantprogenyPericentricinversionheterozygoteFig.13.16Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-16ParacentricinversionheterozygoteFig.13.16Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-17BalancerchromosomesareusefultoolsforgeneticanalysisBalancerchromosomes?Carrymultiple?overlappinginversionsthatpreventrecombinationwithnormalchromosome.Carryadominantmarker?thatproducesavisiblephenotype.Fig.13.17Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-18TranslocationsattachpartofonechromosometoanotherchromosomeTranslocation–partofonechromosomebecomesattachedto?nonhomologouschromosome.Reciprocaltranslocation–twodifferentpartsofchromosomes?switchplaces.Fig.13.18aCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-19AreciprocaltranslocationhelpscausechronicmyelogenousleukemiaCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-20Fig.13.20RobertsoniantranslocationscanreshapegenomesandcontributetoevolutionReciprocalexchangebetweentwoacrocentricchromosomes?generatealargemetacentricchromosomeandasmallchromosome.Willreducechromosomenumberifthesmallchromosomeislost.?Fig.13.19Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-21Thehumanchromosome2maybegeneratedthroughaRobertsoniantranslocationFig.12.11Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-22Robertsoniantranslocationsinhousemiceontheislandof?Madeirageneratedifferentpopulationsofmicewith2n=22,2n=24chromosomes.(2n=40forcommonhousemice)Populationsareclosetobecomingtwospeciesaftercolonizing?theislandonly600yearsago.IIFig13.30Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-23Transposition:ThemovementoftransposableelementsfromoneplacetoanotherinthegenomeTransposableelement:AnysegmentofDNAthatisabletomovefromoneplacetoanotherinthegenome.Foundinallorganisms.SelfishDNAcarryingonlyinformation?toself-perpetuate.1930sMarcusRhoadesand1950sBarbaraMcClintock–transposable?elementsincorn.Mostly50–10,000bplong.?LINEs,longinterspersedelementinmammals,upto6.4kbeachand~?20,000copiesinhumangenome.SINEs,shortinterspersedelements,0.28kbeachand~300,000copies?inhumangenome.Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-24TransposableelementsInsertionsequence(IS)?Transposon(Tn):Transposableelementsthatmove?fromoneplacetoanotherinthegenomewithoutanRNAintermediate.Retroposon:Onetypeoftransposableelementsthat?transposeviareversetranscriptionofanRNAintermediate.Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-25InsertionsequenceInvertedrepeatTransposaseInvertedrepeatCompositetransposonComplextransposonCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-26TransposonsencodetransposaseenzymesthatcatalyzeeventsoftranspositionFig.13.27aCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-27Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-28RetroposonsgenerateanRNAthatencodesareversetranscriptase-likeenzymeTwotypes?Poly-Atailat3’?endofRNA-likeDNAstrandLongterminal?repeat(LTRs)orientedinsamedirectiononeitherendofelementFig.13.26aCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-29Fig.13.26bCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-30Howdoretroposonsmove?Fig.13.26cCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-31GenomesoftencontaindefectivecopiesoftransposableelementsAutonomoustransposableelements–Abletomoveby?themselves.Nonautonomoustransposableelements–Somedeletions?generatedefectiveTEsthatcannotmoveontheirown,butrequiretheactivityofnon-deletedcopiesofsametypeofTEformovement.Adeletionremovesoneoftheinvertedrepeatsatoneendofa?transposon,e.g.mostSINEsandLINEs.Adeletionremovesthepromoterneededforthetranscription?ofaretroposon.Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-32TEscangeneratemutationsinadjacentgenesManyspontaneousmutationsinthewhitegeneofDrosophilaarisefrominsertionsofTEssuchasP,copia,roo,orDoc.Fig.13.28Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-33TEscangeneratechromosomalrearrangementsandrelocategenesFig.13.29Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-34ChangesinchromosomenumberCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-35Euploid:Anindividualthatcarriescompletesetsofchromosomes.Monoploid–carryonlyasinglesetofunpairedchromosomes.?Haploid–carryasinglecompletesetofchromosomesasthose?presentinthegametes.Diploid–carrytwocompletesetsofchromosomes.?Polyploid–carrythreeormorecompletesetsofchromosomes.?Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-36Aneuploid:Anindividualwhosechromosomenumberisnotanexactmultipleofthehaploidnumber(n)forthespecies.Monosomic:Individuallackingonechromosomefromthediploid?number(2n-1)forthespecies.Trisomic:Individualhavingoneextrachromosomeinadditionto?thenormaldiploidset(2n+1)ofthespecies.Tetrasomic:Individualhavingtwoextrachromosomesin?additiontothenormaldiploidset(2n+2)ofthespecies.Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-37AneuploidyisharmfultohumansMonosomies?usuallylethalTrisomies–highly?deleteriousCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-38HumanscantolerateXchromosomeaneuploidybecauseXinactivationcompensatesfordosageBarrbodyCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-39SeveralgenesnearthecentromereandtelomerecanescapeXchromosomeinactivationFig.13.31Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-40AneuploidyresultsfrommeioticnondisjunctionFig.13.32aCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-41Fig.13.32bCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-42MistakesduringmitosiscanproduceclonesofaneuploidcellsMitotic?nondisjunctionFailureoftwosister?chromatidstoseparateduringmitoticanaphaseGeneratesreciprocal?trisomicandmonosomicdaughtercellsChromosomeloss?Producesone?monosomicandonediploiddaughtercellFig.13.33a-bCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-43Aneuploidmosaics–aneuploidandnormaltissues?lieside-by-side.Aneuploidsgiverisetoaneuploidclones.?GynandromorphAraregeneticmosaicwithboth?maleandfemaletissueonthesamebody,usuallyinequalamounts.ResultsfromlosingoneX?chromosomeduringfirstmitoticdivisionofaDrosophilafemalezygote.Fig.13.33cCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-44Someeuploidorganismsarenotdiploids“x”indicatesbasicchromosomenumber-thenumberof?differentchromosomesthatmakeupasinglecompleteset.“n”indicatesthenumberofchromosomesinthegametes.?Diploidspecies:n=xPolyploidspecies:n?xBreadwheat,x=7.Theplant(hexaploid)has2n=6x=42chromosomes.Itsgametes(triploid)hasn=3x=21chromosomes.Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-45MonoploidandpolyploidanimalsarerareMonoploidsMalesinsomespeciesofants,bees,andwasps.?Developedfromunfertilizedeggs.?Malesproducegametesthroughamodifiedmeiosis,whichensuresthatall?thechromosomesaredistributedintoonecell,thegamete.Certainspeciesoffishandlizards.?PolyploidsGoldfishes(tetraploid),earthworms(hermaphrodite).??TriploidandtetraploidfemaleDrosophila.Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-46MonoploidplantscarryasinglecopyofeachchromosomeandareusuallyinfertileFig.13.34aCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-47Monoploidplantshavemanyuses:?Visualizerecessivetraitsdirectly?Introductionofmutationsintoindividualcells?Selectfordesirablephenotypes(herbicideresistance)?Fig.13.34bCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-48TreatmentwithcolchicineconvertsmonoploidcellsthatexpressdesiredphenotypestohomozygousdiploidFig.13.34cCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-49Polyploidyhasaccompaniedtheevolutionofmanycultivatedplants1/3ofknownfloweringplantsarepolyploid.?Polyploidyoftenincreasesplantsizeandvigor.?Oftenselectedforagriculturalcultivation?Triploid–banana?Tetraploids–peanut,alfalfa,coffee,MacIntoshapple,?BarlettpearOctaploid-strawberry?OctaploidDiploidFig.13.37Copyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-50Tetraploids:Arisefromfailureofchromosomestoseparateintotwodaughter?cellsduringmitosisindiploidgermcells.Inplants,tetraploidcanbegenetratedbycolchicinetreatment.?Tetraploidsareoftensourceofnewspecies.?13.36aCopyright?TheMcGraw-HillCompanies,Inc.Permissionrequiredtoreproduceordisplay14-51Triploids:Resultfromunionof?monoploidanddiplo