遺傳學(xué)課件：10第十章 遺傳物質(zhì)的分子基礎(chǔ)

第十章遺傳的分子基礎(chǔ)ProofofDNAasGeneticMaterialTransformation轉(zhuǎn)化inBacteria(FrederickGriffith.1928)CharacteristicsofS.pneumoniae肺炎(鏈)雙球菌StrainsWhenGrownonBloodAgarMedium

ColonyMorphology菌落形態(tài)TypeAppearanceSizeCapsule莢膜Virulence毒性IIRRoughSmallAbsentAvirulentIISSmoothLargePresentVirulent

ColonyMorphologyTypeAppearanceSizeCapsuleVirulenceIIIRRoughSmallAbsentAvirulentIIISSmoothLargePresentVirulent

ReactionwithAntiserumPreparedAgainstTypeTypeIISTypeIIISIIRNoneNoneIISAgglutination凝集None

ReactionwithAntiserumPreparedAgainstTypeTypeIISTypeIIISIIIRNoneNoneIIISNoneAgglutinationDNA:theTransformationMaterial(OswaldAveryandhiscolleagues1944)TheanalyticaltoolsAveryetc.usedwerethefollowing:1.Ultra-centrifugation超速離心2.Electrophoresis電泳3.UltravioletAbsorption紫外吸收4.ElementaryChemicalAnalysis化學(xué)元素分析

TheHershey-ChaseExperimentProofofRNAasGeneticMaterialAvarietyofstrainsoftobaccomosaicvirustobaccomosaicvirus(TMV)exist.ManystrainscausedistinctivesymptomsonindicatorplantsTMVparticlescanbedissociatedinto解離RNAandproteincomponents.TheseparatedRNAandproteincanbemixedtogethertoreforminfectiousviralparticles.ExperimentswithtobaccovirusesrevealedthatRNA,aswellasDNA,couldcarryhereditaryinformation.

vulgaremaskedyellowribgrassnoneMixedparticles,withRNAofonestrainandproteinofanother,canalsobeformed.Mixedparticlesareinfectious.Notethesymptomstheyproduce(C).

CCoatProteinSource

vulgaramaskedyellowribgrass

vulgaramaskedyellowribgrass

RNAsource第二節(jié)核酸的化學(xué)組成及結(jié)構(gòu)分析NucleicAcidChemistryJohannMisecher(1844–1895)“nuclein”.Ribonucleicacids(RNA)Deoxyribonucleicacids(DNA)核糖核苷酸12345脫氧核糖核苷酸核糖2’-脫氧核糖嘧啶環(huán)嘌呤環(huán)胞嘧啶尿嘧啶胸腺嘧啶鳥嘌呤腺嘌呤尿苷脫氧腺苷酸3’-5’磷酸二酯鍵DNAStructureErwinChargaffandChargaff’rulesA=T;C≡GTheDoubleHelixWatsonandCrick(1953)X-raydiffractionphotographoftheBformofpurifiedDNAfibers.DNA雙鏈構(gòu)象改變因素：1、核苷酸順序2、堿基組成3、鹽的種類4、相對濕度Tm(meltingtemperature解鏈溫度)Thetemperatureatwhichapopulationofdouble-strandednucleicmoleculesishalf-dissociatedintosinglestrands.Thisistakentobethemeltingtemperatureforthatspeciesofnucleicacid.Denaturation變性andRenaturation復(fù)性DNA紫外吸收RNA脫氧核糖——核糖；T——U單鏈3.自身互補配對形成雙鏈區(qū)。rRNA(ribosomalRNA)mRNA(messengerRNA)tRNA(transferRNA)snRNA(smallnuclearRNA)antisenseRNAtelomeraseRNAprimer(invivo)DNA的復(fù)制Replication(SemiconservativeReplication)半保留復(fù)制(SemidiscontinuousReplication)半不連續(xù)復(fù)制TheMeselson-StahlexperimentEnzymology酶學(xué)ofDNAReplicationHelicase解旋酶(StrandSeparation)SinglestrandDNA-bindingProteins單鏈DNA結(jié)合蛋白(SSBs)Primerase引物酶(primer)Ligase連接酶Telomerase端粒酶TopoisomerasesII拓?fù)洚悩?gòu)酶(relaxedDNA)dCTP

dTTPdATP

dG