genetics a conceptual approach - pierce, b. a

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1、IntroductiontoGenetics0001IntroductiontoGenetics•RoyalHemophiliaandRomanovDNA•TheImportanceofGeneticsTheRoleofGeneticsinBiologyGeneticVariationistheFoundationofEvolutionDivisionsofGenetics•ABriefHistoryofGeneticsPrehistoryEarlyWrittenRecordsTheRiseofM

2、odernGeneticsTwentieth-CenturyGeneticsTheFutureofGenetics•BasicConceptsinGeneticsAlexis,heirtotheRussianthrone,andhisfatherTsarNicholasRomanoffII.(Hulton/ArchivebyGettyImages.)RoyalHemophiliaallchildrendo.Evenhissmallscrapesbledprofusely,andandRomanov

3、DNAminorbruisesledtosignificantinternalbleeding.ItsoonbecameclearthatAlexishadhemophilia.OnAugust12,1904,TsarNicholasRomanovIIofRussiaHemophiliaresultsfromageneticdeficiencyofbloodwroteinhisdiary:“Agreatnever-to-beforgottendaywhenclotting.Whenabloodvess

4、elissevered,acomplexcascadethemercyofGodhasvisitedussoclearly.”ThatdayAlexis,ofreactionsswingsintoaction,eventuallyproducingapro-Nicholas’sfirstsonandheirtotheRussianthrone,hadbeenteincalledfibrin.Fibrinmoleculessticktogethertoformaborn.clot,whichstemst

5、heflowofblood.Hemophilia,markedbyAtbirth,Alexiswasalargeandvigorousbabywithyel-slowclottingandexcessivebleeding,istheresultifanyonelowcurlsandblueeyes,butat6weeksofagehebeganofthefactorsintheclottingcascadeismissingorfaulty.Inspontaneouslyhemorrhagingf

6、romthenavel.Thebleedingthosewithhemophilia,life-threateningbloodlosscanoccurpersistedforseveraldaysandcausedgreatalarm.Ashewithminorinjuries,andspontaneousbleedingintojointsgrewandbegantowalk,Alexisoftenstumbledandfell,aserodesthebonewithcripplingcons

7、equences.1000ChapterI◗1.1HemophiliawaspasseddownthroughtheroyalfamiliesofEurope.Alexissufferedfromclassichemophilia,whichiscausedwereinevitable,andAlexisexperiencedanumberofseverebyadefectivecopyofageneontheXchromosome.Femalesbleedingepisodes.Theroyal

8、physicianswerehelplessdur-possesstwoXchromosomespercellandmaybeunaffectedingthesecrises—theyhadnotreatmentthatwouldstopthecarriersofthegeneforhemophilia.Acarrierhasonenormalbleeding.GregoryRasputin,amonkandself-proclaimedversionandonedefective