《基因簇和基因重复》PPT课件

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1、Part1.GenesandgenomesChapter4Clustersandrepeats基因簇和重复序列Agenefamilyconsistsofasetofgeneswhoseexonsarerelated;thememberswerederivedbyduplicationandvariationfromsomeancestralgene.Atranslocationisarearrangementinwhichpartofachromosomeisdetachedbybreakageoraberrantrecombinationandthenbecomesattach

2、edtosomeotherchromosome.Ageneclusterisagroupofadjacentgenesthatareidenticalorrelated.4.1 IntroductionNonreciprocalrecombination不等交换(unequalcrossing-over)resultsfromanerrorinpairingandcrossing-overinwhichnonequivalentsitesareinvolvedinarecombinationevent.Itproducesonerecombinantwithadeletionof

3、materialandonewithaduplicatio造成一个缺失一个重复.SatelliteDNA(Simple-sequenceDNA)卫星DNAconsistsofmanytandemrepeats(identicalorrelated)ofashortbasicrepeatingunit.MinisatelliteDNAs小卫星DNAconsistof~10copiesofashortrepeatingsequence.thelengthoftherepeatingunitismeasuredin10sofbasepairs.Thenumberofrepeatsvar

4、iesbetweenindividualgenomes.4.1 IntroductionFigure 6.1Unequalcrossing-overresultsfrompairingbetweennon-equivalentrepeatsinregionsofDNAconsistingofrepeatingunits.4.1 Introduction4.2 GeneduplicationisamajorforceinevolutionFigure 6.2Afteragenehasbeenduplicated,differencesmayaccumulatebetweenthec

5、opies.Thegenesmayacquiredifferentfunctionsoroneofthecopiesmaybecomeinactive.Duplicatedgenesmaydivergetogeneratedifferentgenesoronecopymaybecomeinactive.4.3GlobinclustersareformedbyduplicationanddivergenceFigure 6.3Eachoftheα-likeandβ-likeglobingenefamiliesisorganizedintoasingleclusterthatincl

6、udesfunctionalgenesandpseudogenes.Thebestcharacterizedexampleofageneclusterispresentedbytheglobin球蛋白genes,whichconstituteanancientgenefamily,concernedwithafunctionthatiscentraltotheanimalkingdom:thetransportofoxygenthroughthebloodstream.4.3GlobinclustersareformedbyduplicationanddivergenceFigu

7、re 6.4Differenthemoglobingenesareexpressedduringembyonic,fetal,andadultperiodsofhumandevelopment.Figure 6.5Clustersofβ-globingenesandpseudogenesarefoundinvertebrates.Sevenmousegenesinclude2earlyembryonic,1lateembryonic,2adultgenes,and2pseudog