Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
AdvancedGenetics YeastMarch,2017 HomeworkProblemSet 1.Forthefollowingtetraddata(PD:NPD:T),stateifthegenesare: A. linkedorunlinked B. Iflinked,themapdistancebetweenthegenes C. Centromerelinkage,ifpossible a. 47:53:0 Unlinked(sincePD=NPD),bothlinkedtocentromere b. 45:4:51 Linked(sincePD>>NDP)37.5mapunits c. 20:20:60 Unlinked(sincePD+NPD)notknownifthereiscentromere linkageorifonsamechromosome d. 10:0:90 Linked(sincePD>>NPD),45mapunits 2.DrawchromosomesinMeiosisItoexplain1dinthequestionabove.What property(ies)ofmeiosisarealteredinthiscross. Thereislikelytobeinterferencesothattherearenodoubleexchangesandonly singleexchanges(chiamainterference).90%ofchromsomeswithsinglecrossover and10%withnocrossover. 3.Youperformtetradanalysisontwonewlyisolatedmutants.Thetun1mutant confersresistancetoTunicamycin.Theani1mutantconfersresistanceto anisomycin.Inthetetradsyouobtain,youfind50parentalditypes.Youget10 tetradsthathaveonlytwoviablewild-typeprogenyand40tetradsthathaveonly threeviableprogeny. a. Whatarethelikelygenotypesofthethreeviableprogenyinthelastsetof 40tetrads?Theviablemeioticprogenyarelikelytobe tun1;ANI1 TUNI;ani1 TUN1;ANI1 b. Howdoyouexplaintheinviablityinthecross?Thedoublemutant,tun1; ani1islikelytobelethal.Thetwogenesarealsolinked.Thegene symbolsneedtobeinitalicsorunderlinedtogettheanswercompletely right. 4.YouisolateawildyeaststrainandcrossitbybothMATaandMATαlabstrains. YoufindthatitmateswiththeMATαparent.Whenyoudissectthetetrads,youget onlyabout5%viableprogeny. a. Whatisthelikelyexplanationofthehighlevelofinviability? Itislikelythatthewildyeaststrainisdiploidandthecrossisthentriploid andgeneratesaneuploidyprogenythatareinviable. b. Howwouldyoutestyourexplanationforparta? 5.YoudecidetobrewsomebeerbecauseyoucannotaffordtobuyUrbanChestnut STLIPA.Yougetayeaststrain(LAB1)fromafriend.Whenyoumixitwithawild- strain,thewildstraindies.Yougetasecondstrainfromadifferentfriend(LAB2) andwhenyoumixeditwiththewildstrain,nodeathoccurredandyoumadesome beer. YoudecidetodeterminewhatisthecauseofthekillingphenotypeofLAB1.Youdo acrossofLAB1byLAB2.Luckilytheyhavetherightmating-typealleles.You dissect25tetrads.Foreachofthe100meioticprogeny,youmixthemwiththewild strain.Youfindthatall100progenykillthewild-typestrain. a. Howdoyouexplainthisresult? Cytoplasmicinheritance. b. Whatexperimentwillyoudototestyouridea? 6. Linear tetrads are useful for centromere mapping in Aspergillus and Neurospora. The order can be used to map centromeres. The spores above the midline arise from one meiosis I daughter and the spores below the midline arise from the other meiosis I daughter. A rare Saccharomyces cerevisaie strain gives linear tetrads rather than tetrahedral tetrads that have no order. The two phenotypes are shaded and unshaded Below are tetrads in the order that they were found and scored. Determine if shaded gene is linked to its centromere and what is the distance from the gene to its centromere if it can be determined. 30 8 27 11 9 7 Yeast do not behave as Aspergillus. Rather the meiosis I daughter spindles are offset So that the second and sixth class are showing reductional division. The rest show equational division. So the gene is unlinked to the centromere as only 15 of the 89 tetrads show reductional division. P.S TA thought the answer should be linked, and the distance is 19. 7. Describe the screen used to find autophagy mutants in yeast. a. How would you use multicopy suppression to find genes involved in autophagy? Norightanswer. Whatphenotypewouldyouuse? Useamulticopylibraryin2micronplasmidoruseahighlyexpressedpromoter. Selectforphenotype. Isolateplasmid,sequenceanddeterminegenesthatcanrescueinhighcopynumber.