电脑桌面
添加小米粒文库到电脑桌面
安装后可以在桌面快捷访问

分子生物学(英文版)VIP专享VIP免费

分子生物学(英文版)_第1页
分子生物学(英文版)_第2页
分子生物学(英文版)_第3页
Chapter3NucleicAcid1.PhysicalandchemicalstructureofDNA•Double-strandedhelix•Majorgrooveandminorgroove•Basepairing•Thetwostrandsareantiparallel•G+Ccontent(percentG+C)•SatelliteDNASatelliteDNAconsistsofhighlyrepetitiveDNAandissocalledbecauserepetitionsofashortDNAsequencetendtoproduceadifferentfrequencyofthenucleotidesadenine,cytosine,guanineandthymine,andthushaveadifferentdensityfrombulkDNA-suchthattheyformasecondor'satellite'bandwhengenomicDNAisseparatedonadensitygradient.2.AlternateDNAstructureTwobaseshavebeenextrudedfrombasestackingatthejunction.Thewhitelinegoesfromphosphatetophosphatealongthechain.Oisshownred,Nblue,PyellowandCgrey.3.CircularandsuperhelicalDNADNAcanalsoformadouble-stranded,covalently-closedcircle.Thesecircularmoleculesareoftencoiledintoasuperhelix,theformationofwhichiscatalyzedbyenzymescalledtopoisomerases.4.DenaturationofDNADenaturation:AtransitionfromthenativetothedenaturedstateDNAdenaturation:alsocalledDNAmelting,istheprocessbywhichdouble-strandedDNAunwindsandseparatesintosingle-strandedstrandsthroughthebreakingofhydrogenbondingbetweenthebases.Hyperchromicity/Hyperchromiceffect:thestrikingincreaseinabsorbanceofDNA(A260)causedbythedenaturationofthedouble-strandedDNAmoleculeMeltingtemperature(Tm):thetemperatureatwhichhalfoftheDNAstrandsareinthedouble-helicalstateandhalfaredenatured.Themeltingtemperaturedependsonboththelengthofthemolecule,andthespecificnucleotidesequencecompositionofthatmolecule.FactorsAffectingTm•G-Ccontentofsample•reagentsthatincreasethesolubilityofthebases(anythingthatdisruptsH-bondsorbasestacking)•Saltconcentration•pH•Length5.RenaturationStrandscanbeinducedtorenature(anneal)underproperconditions.Factorstoconsider:•Temperature•Saltconcentration•DNAconcentration•TimeRepetitiveSequences•Unique:SingleCopyGenes•Slightlyrepetitive(2-10copies)•Middlerepetitive(10-hundreds)--Clustered--Dispersed•Highlyrepetitive(hundredstomillions)--ShortsequencesinsatelliteDNA--SequencesofnormallengthincertaingenesthatexistinverylargenumbersC-valueParadoxThereisapparentlyalackofassociationbetweenC-value(theamountofDNApresentinthehaploidgenomeofdifferentorganisms)andthedegreeoforganismalcomplexityofvariousmulti-cellularorganisms.In1971,Thomasnamedthisphenomenon,C-valueParadox.在每一种生物中其单倍体基因组的DNA总量是特异的,被称为C值(CValue)。C值和生物结构或组成的复杂性不一致的现象称为C值悖论(C-valueparadox)。6.HybridizationHybridization:thetechniquewhereinrenaturedDNAisformedfromseparatesingle-strandedsamples.Heteroduplexing:renaturationcombinedwithelectronmicroscopyinaprocedureallowsthelocalizationofcommon,distinct,andmissingsequencesinDNA.DNA-RNAhybridization(Northernhybridization):theuseoffilterhybridizationtodetectsequencecomplementaritybetweenasinglestrandofDNAandanRNAmolecule.7.ThestructureofRNATypes:mRNA,tRNA,rRNADistinctions:-ribosereplacesdeoxyribose;-UreplacesT;-Single-strandedConformation:stem-looporhairpin8.HydrolysisofnucleicacidThephosphodiesterbondsofbothDNAandRNAcanbebrokenbyhydrolysiseitherchemicallyorenzymatically.Ribozymes:theRNAenzymes,areabletocleaveandformspecificphosphodiesterbondsinamanneranalogoustoproteinenzymes.Chapter6ThegeneticmaterialThePathtotheWatsonandCrickModel1928,Griffith,transformationinpneumococci(肺炎球菌)19,Avery,GriffithstransformingprinciplewasDNA1950,Chargaff,apatternintheamountsofthefourbases19...

1、当您付费下载文档后,您只拥有了使用权限,并不意味着购买了版权,文档只能用于自身使用,不得用于其他商业用途(如 [转卖]进行直接盈利或[编辑后售卖]进行间接盈利)。
2、本站所有内容均由合作方或网友上传,本站不对文档的完整性、权威性及其观点立场正确性做任何保证或承诺!文档内容仅供研究参考,付费前请自行鉴别。
3、如文档内容存在违规,或者侵犯商业秘密、侵犯著作权等,请点击“违规举报”。

碎片内容

确认删除?
VIP
微信客服
  • 扫码咨询
会员Q群
  • 会员专属群点击这里加入QQ群
客服邮箱
回到顶部