第十一章基因結(jié)構(gòu)和重組

SupplementsMutantstrainNothingOrnithineCitrullineArginino-ArginineGrowthresponseifnutrientisaddedtominimalmedium

succinate

WildtypeArg++++++Arg-E--++++Arg-F--

-+++Arg-G----++Arg-H-----+

Neurosporacrassa粗糙鏈孢霉鳥(niǎo)氨酸瓜氨酸精氨酸琥珀酸精氨酸乙酰鳥(niǎo)氨酸酶乙酰鳥(niǎo)氨酸鳥(niǎo)氨酸瓜氨酸鳥(niǎo)氨酸轉(zhuǎn)氨甲?；妇彼徵晁岷铣擅妇彼徵晁崃呀饷妇彼徵晁峋彼崽於彼岚奔柞Ａ姿酦eurosporacrassa乙酰醋酸尿黑酸氧化酶尿黑酸對(duì)羥甲基苯丙酮酸對(duì)羥甲基苯丙酮酸氧化酶酪氨酸苯丙氨酸轉(zhuǎn)氨酶苯丙氨酸羥化酶苯丙酮酸黑色素3,4二羥苯丙氨酸延胡索酰乙酰乙酸延胡酸乙酰乙酸苯丙氨酸苯丙氨酸羥化酶轉(zhuǎn)氨酶對(duì)羥甲基苯丙酮酸氧化酶acid尿黑酸氧化酶酪氨酸對(duì)羥甲基苯丙酮酸尿黑酸乙酰醋酸苯丙酮酸黑色素呆小癥甲狀腺酪氨酸代謝紊亂尿黑酸癥腦損害白內(nèi)障黃疸肝臟腫大腎損害半乳糖激酶1—磷酸半乳糖尿苷二磷酸葡萄糖葡萄糖—1—磷酸尿苷轉(zhuǎn)移酶尿苷二磷酸半乳糖差向異構(gòu)酶

onegene–onepolypeptidetheory9大家應(yīng)該也有點(diǎn)累了，稍作休息大家有疑問(wèn)的，可以詢問(wèn)和交流GeneStructure

generecombinationandcis-transtestandcistronAspergillusnidulans曲霉菌heterokaryon異核體diploidconidia二倍體分生孢子ad16++ad8ad16++ad8ad16++++ad16ad8ad8++++ad16ad16ad8ad8突變型野生型野生型突變型ad16+ad16+++ad8ad8transciscis-transeffectcistron有缺陷有缺陷有缺陷正常野生型突變型plementationtest

BK()

+-++rIIrII+T4T4突變型rII+在不同菌株上的噬菌斑(大而清晰)(小而模糊)(小而模糊)(E、coli)重組測(cè)驗(yàn):r47+×+r104;B,總數(shù);K(),重組子BenzerrII:rIIAandrIIB(twocistrons)互補(bǔ)m1m2++m1+

+m2

m1m2++m1++m2順式反式順式反式同一順?lè)醋硬煌樂(lè)醋右吧屯蛔冃鸵吧鸵吧蚠_無(wú)互補(bǔ)互補(bǔ)實(shí)驗(yàn)可確定有同一表型效應(yīng)得兩個(gè)突變型就是等位得還就是非等位得。(一)重組機(jī)制

1、交叉理論(chiasmatatypehypothesis)1909年Janssens并提出了交叉型理論2、斷裂愈合模型1937年Darlington提出3、模板選擇學(xué)說(shuō)(copychoice)BellingJ、首先提出得,1933年她又撤回了這一假設(shè)。4、1948年Hershey提出模板選擇學(xué)說(shuō)斷裂重接模型和模板選擇復(fù)制模型得否定斷裂重接模型不能解釋基因轉(zhuǎn)變和極化子現(xiàn)象模板選擇復(fù)制模型存在得問(wèn)題:(1)違背了半保留復(fù)制;(2)DNA復(fù)制應(yīng)在S期,重組應(yīng)在M期,不應(yīng)同時(shí)發(fā)生。(3)不能解釋3線和4線交換?；蜣D(zhuǎn)變GeneconversionP132單倍體菌絲A單倍體菌絲B二倍體合子基因轉(zhuǎn)變(Geneconversion):將真菌中不規(guī)則分離現(xiàn)象解釋為減數(shù)分裂過(guò)程中同源染色體聯(lián)會(huì)時(shí),一個(gè)基因使相對(duì)位置上得基因發(fā)生相應(yīng)得變化所致,因而稱為基因轉(zhuǎn)變。HybridDNAmodelbranchmigrationofHollidaystructure

EMofaHollidayJunctionw/afewmeltedbasepairsaroundjunctionTheMeselson-RaddingModelSincetheHollidaymodelproposestwosimultaneoussinglestrandnickstostarteverythingoff,anothermodelwasproposedbyCharlesRaddingandMatthewMeselson、Inthismodel,onlyonestrandinvasionisrequired、雙鏈斷裂起始重組模型(P129)在酵母系統(tǒng)得重組研究中,發(fā)現(xiàn)載體DNA雙鏈斷裂可大大提高同源重組得效率。TherecBCDPathwayofHomologousRebinationPartI:NickingandExchanging細(xì)菌同源重組機(jī)制RecBCD:AplexenzymeRecBCDhas:Endonucleasesubunits(recBC)thatcut oneDNAstrandclosetoChisequence、DNAhelicaseactivity(recDsubunit)andDNA-dependentATPaseactivityunwindsDNAtogenerateSSregionsActivity2and3linked

recBCDPathwayofHomologousRebination

PartI:NickingandExchangingAnickiscreatedinonestrandbyrecBCDataChi sequence(GCTGGTGG),foundevery5000bp、UnwindingofDNAcontainingChisequenceby recBCDallowsbindingofSSBandrecA、

recApromotesstrandinvasionintohomologous DNA,displacingonestrand、Thedisplacedstrandbase-pairswiththesingle strandleftbehindontheotherchromosome、Thedisplacedandnowpairedstrandisnicked (byrecBCD?)topletestrandexchange、

recBCDPathwayofHomologousRebination

PartII:BranchMigrationandResolutionrecBCDPathwayofHomologousRec、

PartII:BranchMigrationandResolutionNicksaresealed

HollidayJunctionBranchmigration(ruvA+ruvB)ResolutionofHollidayJunction(