资源描述：
《沃森和克利描述结构的脱氧核糖核酸137030032》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、WatsonandCrickdescribestructureofDNA(1953)Photo:ModelofDNAmoleculeInthelatenineteenthcentury,aGermanbiochemistfoundthenucleicacids,long-chainpolymersofnucleotides,weremadeupofsugar,phosphoricacid,andseveralnitrogen-containingbases.Lateritwasfoundthatthesu
2、garinnucleicacidcanberiboseordeoxyribose,givingtwoforms:RNAandDNA.In1943,AmericanOswaldAveryprovedthatDNAcarriesgeneticinformation.HeevensuggestedDNAmightactuallybethegene.Mostpeopleatthetimethoughtthegenewouldbeprotein,notnucleicacid,butbythelate1940s,DN
3、Awaslargelyacceptedasthegeneticmolecule.Scientistsstillneededtofigureoutthismolecule'sstructuretobesure,andtounderstandhowitworked.In1948,LinusPaulingdiscoveredthatmanyproteinstaketheshapeofanalphahelix,spiraledlikeaspringcoil.In1950,biochemistErwinCharga
4、fffoundthatthearrangementofnitrogenbasesinDNAvariedwidely,buttheamountofcertainbasesalwaysoccurredinaone-to-oneratio.ThesediscoverieswereanimportantfoundationforthelaterdescriptionofDNA.Intheearly1950s,theracetodiscoverDNAwason.AtCambridgeUniversity,gradu
5、atestudentFrancisCrickandresearchfellowJamesWatson(b.1928)hadbecomeinterested,impressedespeciallybyPauling'swork.MeanwhileatKing'sCollegeinLondon,MauriceWilkins(b.1916)andRosalindFranklinwerealsostudyingDNA.TheCambridgeteam'sapproachwastomakephysicalmodel
6、stonarrowdownthepossibilitiesandeventuallycreateanaccuratepictureofthemolecule.TheKing'steamtookanexperimentalapproach,lookingparticularlyatx-raydiffractionimagesofDNA.In1951,WatsonattendedalecturebyFranklinonherworktodate.ShehadfoundthatDNAcanexistintwof
7、orms,dependingontherelativehumidityinthesurroundingair.Thishadhelpedherdeducethatthephosphatepartofthemoleculewasontheoutside.WatsonreturnedtoCambridgewitharathermuddyrecollectionofthefactsFranklinhadpresented,thoughclearlycriticalofherlecturestyleandpers
8、onalappearance.Basedonthisinformation,WatsonandCrickmadeafailedmodel.ItcausedtheheadoftheirunittotellthemtostopDNAresearch.Butthesubjectjustkeptcomingup.Franklin,workingmostlyalone,foundthatherx-raydiffractionsshowe
