四分子分析课件

Ascomycetes()Ascomycetesarefungithatformtheirmeioticprogenyinaasci(ascus,).Thisallowstheproductsofmeiosis(calledatetrad，四分子)toberecoveredtogether.Someascomyceteshaveorderasci.UnorderedTetradOrderedTetrad粗糙链孢霉酿酒酵母Ouroldfriend,NeurosporaNeurospora

isahaploidorganismthatmakes

asci

with8spores.NeurosporaLifecycle粗糙链孢霉同时的

教材p70一种能产生分生孢子的特殊真菌菌丝植物生长的

ProducinganOrderedTetrad性细胞

NeurosporaMeiosisThisshowstheprocessofmeiosisinN.crassa.Rememberthattheduplicatedchromosomesthatareheldtogetherbythecentromeresegregateduringthefirstmeioticdivision.Thus,alocusthatisclosetothecentromerewouldoftensegregateduringthefirstmeioticdivision.MISegregationPatternAfirst-divisionsegregationpattern,MINocrossoverbetweengeneandcentromereProducingMIISegregationPatterns教材p180的4种交换型Tetradsproducedbyseconddivisionsegregationarerelatedtothedistancefromthecentromerebythisequation:R=(1/2second-divison/total)x100%=cMOrderedTetradsinNeurosporaAllowMappingRelativetotheCentromere½MII/totalx100%=cMOrGeneticAnalyseswithTetradsaba+b+XCrosstwohaploidcellsaba+b+InducediploidtoundergomeiosisProducingMIISegregationPatternsThedistanceincMbetweenaandbcanbeestimated.ParentalDitype(PD)Tetratype(TT)NonparentalDitype(NPD)这没有完全概括教材的P185，请补充完整CalculatingGeneticDistances

withTetradAnalysisOrdered(Linear)ExampleNeurosporaGene-GeneDistanceRF=1/2T+NPDtotalGene-CentromereDistance½MII/totalPage184(教材上册)ababa+b+a+b+ab+ab+a+ba+babab+a+b+a+baba+ba+b+ab+aba+b+a+b+abab+a+ba+bab+ab+a+ba+b+ab711181801TypeForaForbNPDMIMITMIMIITMIIMIPDMIIMIINPDMIIMIIPDMIMITMIIMIIPage184(教材上册)Distancefromatocentromere=½MII=½(1+8+1)=0.05=5mapunitsTotal 100Distancefrombtocentromere=½MII=½(18+8+1)=.135=13.5mapunitsTotal 100Distancefromatob=½T+NPD

=½(18+1+1)+1=