英文医学培训课件：DNA 2015 4.pdf

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1、Chapter162015-9-28Contents•Characteristics1•Process&Component2•Reversetranscription3Section1CharacteristicsofDNAreplicationReplicationFactsNewcellsidenticaltoparentcellsNewDNAidenticaltoparentDNADNAiscopiedbeforecelldivision.DNAiscopiedduringSphaseofinterphase4Cellduplication•Sphaseduringinterph

2、aseofthecellcycle•NucleusofeukaryotesSDNAreplication.•G1•interphase•G2•Mitosis•-prophase•-metaphase•-anaphase5•-telophaseCentraldogmareplicationtranscriptiontranslationDNARNAproteinreversetranscription6GeneralConceptsreplicationparentalDNAdaughterDNA•daughterDNAsaresynthesized•parentalDNAsastemp

3、late.•geneticinformationflow7CharacteristicsofreplicationSemi-conservativereplicationHighfidelityOri,BidirectionReplicationforkSemi-discontinuousreplicationPrimer&others8ComponentsrequiredforreplicationTemplate:doublestrandedDNASubstrate:dNTPEnzyme:DNA-dependentDNApolymerase(DDDP),otherenz

4、ymes,proteinfactorsPrimer:shortRNAfragmentwithafree3´-OHend9ProposedModelsInthelate1950s,threehypotheses.10(一)semiconservativereplication"Heavy"DNA(15N)growin14NmediumThefirstgenerationgrowin14NmediumThesecondgeneration11•CsClDensityGradientCentrifugationDNA14N15N12DataInterpreting•After~twogene

5、rations,•onegeneration,DNAisoftwotypes:“light”“half-heavy”and“half-heavy”•Thisisconsistentwithonly13thesemi-conservativemodel14Significancetransfergeneticinformationfidelitynextgeneration15(二)ReplicationinitiationDNAsynthesisbeginsatasitetermedtheoriginofreplicationInitiationofReplication•Theori

6、ginofreplicationinE.coliistermedoriC–originofChromosomalreplication–AT-richregion17–DnaAboxes(三)BidirectionalReplication•SynthesisofDNAproceedsbidirectionallyaroundthebacterialchromosome18DNAreplicationwithtwoforksReplicon19ReplicationforksvisibleinDrosophila20BacterialDNAreplication----oneorigi

7、ntwodirection21Multipleoriginsineukaryotes,twodirections5'3'3'5'bidirectionalreplicationfusionofbubbles5'3'3'5'5'3'3'5'22•Differentregionsreplicatedatdifferenttimes23Replicationofthetwostrands3'5'replicationfork3'5'3'5'repli