四分子分析課件

Ascomycetes()Ascomycetesarefungithatformtheirmeioticprogenyinaasci(ascus,).Thisallowstheproductsofmeiosis(calledatetrad，四分子)toberecoveredtogether.Someascomyceteshaveorderasci.UnorderedTetradOrderedTetrad粗糙鏈孢霉釀酒酵母Ouroldfriend,NeurosporaNeurospora

isahaploidorganismthatmakes

asci

with8spores.NeurosporaLifecycle粗糙鏈孢霉同時(shí)的

教材p70一種能產(chǎn)生分生孢子的特殊真菌菌絲植物生長(zhǎng)的

ProducinganOrderedTetrad性細(xì)胞

NeurosporaMeiosisThisshowstheprocessofmeiosisinN.crassa.Rememberthattheduplicatedchromosomesthatareheldtogetherbythecentromeresegregateduringthefirstmeioticdivision.Thus,alocusthatisclosetothecentromerewouldoftensegregateduringthefirstmeioticdivision.MISegregationPatternAfirst-divisionsegregationpattern,MINocrossoverbetweengeneandcentromereProducingMIISegregationPatterns教材p180的4種交換型Tetradsproducedbyseconddivisionsegregationarerelatedtothedistancefromthecentromerebythisequation:R=(1/2second-divison/total)x100%=cMOrderedTetradsinNeurosporaAllowMappingRelativetotheCentromere?MII/totalx100%=cMOrGeneticAnalyseswithTetradsaba+b+XCrosstwohaploidcellsaba+b+InducediploidtoundergomeiosisProducingMIISegregationPatternsThedistanceincMbetweenaandbcanbeestimated.ParentalDitype(PD)Tetratype(TT)NonparentalDitype(NPD)這沒(méi)有完全概括教材的P185，請(qǐng)補(bǔ)充完整CalculatingGeneticDistances

withTetradAnalysisOrdered(Linear)ExampleNeurosporaGene-GeneDistanceRF=1/2T+NPDtotalGene-CentromereDistance?MII/totalPage184(教材上冊(cè))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(教材上冊(cè))Distancefromatocentromere=?MII=?(1+8+1)=0.05=5mapunitsTotal 100Distancefrombtocentromere=?MII=?(18+8+1)=.135=13.5mapunitsTotal 100Distancefromatob=?T+NPD

=?(18+1+1)+1=