武汉大学 分子生物学全部课程 3.ppt

《武汉大学 分子生物学全部课程 3.ppt》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、WelcomeEachofYoutoMyMolecularBiologyClassMolecularBiologyoftheGene,5/E---Watsonetal.(2004)PartI:ChemistryandGeneticsPartII:MaintenanceoftheGenomePartIII:ExpressionoftheGenomePartIV:RegulationPartV:Methods3/08/05PartII:MaintenanceoftheGenomeDedicatedtothestructure

2、ofDNAandtheprocessesthatpropagate,maintainandalteritfromonecellgenerationtothenextMaintenanceoftheGenomeCh6:ThestructuresofDNAandRNACh7:Chromosomes,chromatinsandthenucleosomeCh8:ThereplicationofDNACh9:ThemutabilityandrepairofDNACh10:Homologousrecombinationatthemo

3、lecularlevelCh11:Site-specificrecombinationandtranspositionofDNA3/08/05CHAPTER6TheStructuresofDNAandRNAHowdothestructuresofDNAandRNAaccountfortheirfunctions?OUTLINE1.DNAStructure2.DNATopology3.RNAStructureDNASTRUCTUREDNASTRUCTURE(1)DNAiscomposedofpolynucleotidech

4、ainsStructure:twistingaroundeachotherintheformofadoublehelix.SchematicmodelSpace-fillingmodelNucleoside&Nucleotide,thefundamentalbuildingblockofDNAglycosidicbondphosphoesterbondDNApolarity:isdefinedbytheasymmetryofthenucleotidesandthewaytheyarejoined.Phosphodiest

5、erlinkages:repeating,sugar-phosphatebackboneofthepolynucleotidechainBasesinDNApurinespyrimidinesadenineguaninecytosinethymineN9N1DNASTRUCTURE(2)Eachbaseshasitspreferredtautomericform(RelatedtoCh9)Thetwostrandsofthedoublehelixareheldtogetherbybasepairinginanantipa

6、rallelorientation,Whichisastereochemicalconsequenceofthewaythatadenineandthymine,andguanineandcytosine,pairwitheachother.(Relatedtoreplicationandtranscription)DNASTRUCTURE(3)TheTwoChainsoftheDoubleHelixHaveComplementarySequencesExample:Ifsequence5’-ATGTC-3’ononec

7、hain,theoppositechainmusthavethecomplementarysequence3’-TACAG-5’DNASTRUCTURE(4)Watson-CrickBasePairing(Relatedtoreplicationandtranscription)Thestrictnessoftherulesfor“Waston-Crick”pairingderivesfromthecomplementaritybothofshapeandofhydrogenbondingpropertiesbetwee

8、nadenineandthymineandbetweenguanineandcytosine.A:CincompatibilityHydrogenBondingIsImportantfortheSpecificityofBasePairingDNASTRUCTURE(5)Thehydrogenbondsbetween