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ID:37149211
大小:1.87 MB
页数:39页
时间:2019-05-10
《中南大学 生物化学 考研课件 ch30-33 信息传递 Information Transfer》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、InformationTransfer(inprocaryotes)ForSpecialtyofBiotechnologyorBioengineeringatCSUMr.XIAJinlanContentDNAreplicationTranscriptionandtheregulationofgeneexpressionProteinsynthesisInformationtransferflowDNAreplicationinprokaryotesMainpointsReplicationstartsatasingl
2、eoriginReplicationisbi-directionalandsemi-conservativeEachreplicationbubble(oreye)consistsoftworeplicationforksGrowthatthereplicationforksisdiscontinuousProteinsinvolvedinDNAreplicationPrimasePolymeraseI(PolI),PolII,PolIIILigasehelicaseReplicationisbidirectiona
3、lUnidirectionalreplicationhasbeenobservedonlyinbacteriophagesandsomeplasmidsp988ReplicationissemidiscontinuousOkazakifragments冈崎片段p989Thegeneralreaction:(DNA)nresidues+dNTP(DNA)n+1+PPiRequirementsforDNAsynthesisPolymeraseI(orpolymeraseIII+polymeraseI)AllfourdN
4、TPsMg2+ADNAtemplateAprimer启动子withafree3’-OHDNAreplication:overviewRequirementsforDNAsynthesisBasicprocedureofDNAreplicationPrimerbindstotheDNAtemplatestrandbybasepairingprinciplePolymeraseIrecognizesthenucleotideAontheDNAtemplatestrandPolymeraseIdirectsthenucle
5、otideT(pairingtoA)3’-OHoftheprimernucleophilicattackstothea-phosphategroupoftheincomingnucleotideTheprimerextendsina5’to3’directionChainelongationreactioncatalyzedbyDNApolymeraseDNApolymerases---theenzymesofDNAreplicationinprocaryotesPropertiesPolIPolIIPolIIIPo
6、lymerization5’→3’√~20bases√√>4.6MegaBasesExonuclease3’→5’√√√Exonuclease5’→3’√××DNApolymeraseIandIIfunctionprincipallyinDNArepair;DNApolymeraseIIIisthechiefDNA-replicatingenzymep9913’→5’exonucleaseactivityofDNApolymeraseITocorrectthemismatchedbasesfrom3’endThe5’
7、3’exomucleaseactivityofDNApolymeraseIRemovetheRNAprimerfrom5’endNickfillingGeneralfeaturesofareplicationforkFigure30.15onp997Pleasefindwhatkindsenzymesareincluded.WherearetheOkazakifragmentsandlaggingstrand?Wherearetheleadingstrand?Concept-checkpointsTowhichend
8、ofanewlysynthesizedstrandofDNAdoespolymeraseaddabase?WhyisaprimerrequiredforDNAreplication?Whataretheleadingandlaggingstrands?Whatisthefunctionofprimer?Whatarethedifferences
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