生物化学 核苷酸和核酸

§8.1Nucleotides(核苷酸)§8.2NucleicAcids(核酸)§8.3NucleicAcidChemistry§8.4OtherFunctionsofNucleotides§8Nucleotides&nucleicacids1b-RibonucleotideD-2b-D-deoxyribonucleotide3Basesinnucleotides4§8.2NucleicAcidsBriefHistoryaboutDNADNAStructureRNAStructure51869,Miescherisolatesnuclein1928,GriffithfindsStreptococcustransformation1944,AverydiscoveredthatDNAwasthegeneticmaterialBy1947,ChargaffhaddevelopedaseriesofrulesbasedonasurveyofDNAcompositioninorganismsEarlyin1950s,Wilkins&FranklinusedX-raycrystallographytostudythestructureofDNA1952,HersheyfarthershowedthatDNAwasthegeneticmaterial1953,Watson&Crick

proposethedouble-helicalstructureofDNA......BriefHistoryaboutDNA61928,Griffith’stransformationexperiment(1)71928,Griffith’stransformationexperiment(2)81928,Griffith’stransformationexperiment(3)91928,Griffith’stransformationexperiment(4)Return101944,Avery-MacLeod-McCartyexperimentReturn11Franklin’sX-raypictureforDNAReturn121952,AlfredD.Hershey&MarthaChaseexperimentReturn13Return14DNAStructureDoubleHelix15DNAStructure:doublehelix16A-DNAB-DNAZ-DNAAllcontain21basepairsDNAStructure:threehelixforms(1)17A-DNAB-DNAZ-DNADNAStructure:threehelixforms(2)B-DNA:生理条件下最稳定的构象；A-DNA:片段DNA在晶体状态下的构象，尚未知在细胞中是否存在；Z-DNA:生理条件下局部DNA可存在的构象，它表是该段DNA可能处于活动状态——转录、重组等.18DNAStructure:Palindromes&mirrorrepeats19DNAStructure:Hairpin20DNAStructure:Cruciform21DNAStructure:threeDNAstrandsHoogsteenPairsWaston-CrickPairs22DNAStructure:HDNA23DNAStructure:fourDNAstrands(1)24DNAStructure:fourDNAstrands(2)25UnusualDNAstructures(includingtriplehelixandtetraplex)tendtoappearatsiteswhereimportanteventsinDNAmetabolism(replication,recombination,transcription)areinitiatedorregulated2627282930§8.1Nucleotides(核苷酸)§8.2NucleicAcids(核酸)§8.3NucleicAcidChemistry§8.4OtherFunctionsofNucleotides§8Nucleotides&nucleicacids31UVabsorption32Double-helicalDNA&RNAcanbedenatured(1)33MeltingpointDouble-helicalDNA&RNAcanbedenatured(2)34Nucleicacidhybrid35Nonenzymatictransformations(1)36Nonenzymatictransformations(2)37FormationofpyrimidinedimersinducedbyUVlight38Recovery39SomebasesofDNAaremethylated40DNASequencingDNApolymerase4142Sangermethodisalsocalleddideoxymethod43荧光标记的策略之一44DNApolymerasedATP,dGTP,dTTP,dCTPddATPDNApolymerasedATP,dGTP,dTTP,dCTPddGTPDNApolymerasedATP,dGTP,dTTP,dCTPddTTPDNApolymerasedATP,dGTP,dTTP,dCTPddCTPddATPddATPddATPddGTPddGTPddGTPddTTPddTTPddTTPddCTPddCTPddCTP荧光标记的策略之二45ChemicalsynthesisofDNAHasbeenautomated464748§8.1Nucleotides(核苷酸)§8.2NucleicAcids(核酸)§8.3NucleicAcidChemistry§8.4OtherFunctionsofNucleotides§8Nucleotides&nucleicacids49Nucleotidescarry