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1、第四章孟德尔遗传定律Mendel’sprinciples第一节分离规律1.1Mendel’sExperimentsGregorJohannMendel(1822-84)Mendel,bornin1822,grewupinaruralareaofwhatisnowapartofCzechoslovakia.Becausehisfamilywaspoor,heenteredamonasteryinordertocontinuehiseducation.Mendelhadalifelonginterestinbiology,parti
2、cularlyanimalbreeding,butbecausehissuperiorsdidnotthinkitappropriateforaclerictobreedanimals,heconcentratedinsteadonraisinggardenpeasandotherplantsinthemonasterygarden.1.1Mendel’sExperimentsTheresultsofhisworkwerepublishedinGermaninan1866paperentitled“experimentsinPl
3、antHybridization.”Thepaperwasdistributedfairlywidelythroughlibraries,butMendel’scontemporariesdidnotunderstandhisfindings,probablypartlybecauseofthemathematicalexplanationsasteryin1868andpublishednothingfurtheronhereditybytherestofthescientificcommunityuntil1900,when
4、threebotanists,CarlCorrensinGermany,HugodeVriesintheNetherlands,andErichvonTschermakinAustria,rediscoveredhisworkaftereachhadapparentlyindependentlyreachedsimilarconclusions.1.1.1孟德尔遗传分析的方法严格选材从豆科植物中选择了自花授粉且是闭花授粉的豌豆作为杂交试验的材料。精心设计采取单因子分析法。定量分析法首创了测交方法WhyMendelchoset
5、hepeaplant?Thegardenpeawaseasytocultivateandhadrelativelyshortlifecycle.Theplanthaddiscontinuouscharacteristicssuchasflowercolorandpeatexture.Inpartbecauseofitsanatomy,pollinationoftheplantcouldbecontrolledeasily.Foreignpollencouldbekeptout,andcross-fertilizationcou
6、ldbeaccomplishedartificially.1.1.2Concernedconcept杂交(cross):在遗传分析中有意识地将两个基因型不同的亲本进行交配称杂交。F1(Filialgeneration):由两个基因型不同的亲本杂交产生的种子及长成的植株。F2:由F1自交或互交产生的种子及长成的植株。杂种(hybrid):任何不同基因型的亲代杂交所产生的个体。.1.1.2ConcernedconceptP:亲本;♀:母本;♂:父本;:自交。1.1.2Concernedconcept显性基因(dominantgen
7、e):在杂合状态下,能够表现其表型效应的基因,一般以大写字母表示。隐性基因(recessivegene):在杂合状态下,不表现其表型效应的基因,一般以小写字母表示。等位基因(Allele):在同源染色体上占据相同座位的两个不同形式的基因,一般是由突变所造成的。AaAstemandpodsofthegardenpeaplant(Pisumsativum)TheanatomyandlifecycleofthepeaplantArtificialcrossofawhite-flowered(maleparent)withaviole
8、t-flowered(femaleparent)peaplantThesevenpairsofcharacteristicsingardenpeasthatMendelstudied1.1.3Mendel’sexperimentsP♀圆×皱♂圆F1若将左边的例子