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1、孟德尔遗传定律Mendel’sprinciples第二章1.1Mendel’sExperimentsGregorJohannMendel(1822-84)Mendel,bornin1822,grewupinaruralareaofwhatisnowapartofCzechoslovakia.Becausehisfamilywaspoor,heenteredamonasteryinordertocontinuehiseducation.Mendelhadalifelonginterestinbiology,p
2、articularlyanimalbreeding,butbecausehissuperiorsdidnotthinkitappropriateforaclerictobreedanimals,heconcentratedinsteadonraisinggardenpeasandotherplantsinthemonasterygarden.1.1Mendel’sExperimentsTheresultsofhisworkwerepublishedinGermaninan1866paperentitled“
3、experimentsinPlantHybridization.”Thepaperwasdistributedfairlywidelythroughlibraries,butMendel’scontemporariesdidnotunderstandhisfindings,probablypartlybecauseofthemathematicalexplanationsasteryin1868andpublishednothingfurtheronhereditybytherestofthescienti
4、ficcommunityuntil1900,whenthreebotanists,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
5、采取单因子分析法。定量分析法首创了测交方法WhyMendelchosethepeaplant?Thegardenpeawaseasytocultivateandhadrelativelyshortlifecycle.Theplanthaddiscontinuouscharacteristicssuchasflowercolorandpeatexture.Inpartbecauseofitsanatomy,pollinationoftheplantcouldbecontrolledeasily.Forei
6、gnpollencouldbekeptout,andcross-fertilizationcouldbeaccomplishedartificially.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第一代杂种,由F1自交或互交产生的第二代杂种称F2代。杂种(hybrid):任何不同基因型的亲代杂交所产生的个体。Monohybrids:Offspringofpa
7、rentsthatdifferinonlyonegeneticcharacteristic.Usuallyimpliesheterozygosityatasinglelocusunderstudy.1.1.2Concernedconcept显性基因(dominantgene):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
8、般是由突变所造成的。AaAstemandpodsofthegardenpeaplant(Pisumsativum)TheanatomyandlifecycleofthepeaplantArtificialcrossofawhite-flowered(maleparent)withaviolet-flowered(femaleparent)peaplantThesevenpairsofcharacteristic