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
ChromoSockMitosis InstructorProtocol Overview Inthisactivity,studentswilluseChromoSockstomodelthebehaviorofchromosomesduringmitosis. Studentswillsimulatethemovementofchromosomesduringcelldivision.Usingaphysicalmanipulative likeChromosocksprovidesvisualcluesofstudentconceptsthatcanbeusedtoaddresscommon chromosomemisconceptions LearningObjectives: Definehaploidanddiploid Identifychromosomenumberatseveralpointsduringmitosis Identifymitosisasthedivisionthatproducesidentical‘daughtercells’ Modelmitosis Correctlylabelcentromere,chromosome(bothreplicatedandnon-replicated)andchromatidsinadiagram Materials 2BagsofChromosocksforeachpairofstudents.Eachbagcontains: 1whiteChromoSockwithanorangestripelabeled“F” 1whiteChromoSockwithanorangestripelabeled“f” 1beigeChromoSockwithagreenstripelabeled“B” 1beigeChromoSockwithagreenstripelabeled“b” 1greyChromoSockwithablackstripelabeled“N” 1greyChromoSockwithablackstripelabeled“n” Rubberbands ChromoSockWorksheet Timeframe Thisactivityisdesignedtobecompletedinasingleclassperiod. © 2016 HudsonAlpha Institute for Biotechnology IntroducingMitosis 1.DistributeabagcontainingonesetofChromoSockstoeachpair(group)ofstudents. RemindstudentsthatDNAisfoundinthenucleusofeachcell.Somatic(allbodycells,except reproductivecells)cellsundergomitosis. 2.DirectstudentstoremovetheChromoSocksandarrangeinpairs.Chromosomes,likesocks,occurin pairs.Thesepairsarecalledhomologs.Studentswilldrawthecellandlabelthechromosomeploidyand number.Studentsaretousean“I”shapetorepresentasinglechromosome;laterintheactivityan“)(” shapewillbeusedtorepresentareplicatedchromosome. Remindstudentsthateachindividualhasonecompletesetofchromosomes,halfofwhichcamefrom motherandtheotherhalffromfather.Pointoutthatalthoughthesocksmayappearslightlydifferent, onecaneasilydeterminewhichtwoshouldbepaired.Askstudentsiftheycanidentifywhichofeachpair ofchromosomescamefromthefatherandwhichcamefromthemother.Answer:No. Askstudentshowmanytotalchromosomesarepresent?Answer:6(six). Askhowmanypairsofchromosomesarepresent.Answer:3(three).Thesecellsarediploidandthe diploidchromosomenumberis6forthishypotheticalorganism. Usingthechartoforganismsbelow,exploreconceptsofdiploidandhaploidchromosomenumberwith students. Chromosomenumberacrossvariousorganisms Organism CommonName DiploidChromosome# Giraffacamelopardalis Giraffe 62 Pantheraleo Lion 38 Zeamays Maize/Corn 20 Ananascomosus Pineapple 50 Lumbricusterrestris Earthworm 36 3.TheChromosockswillnowbeusedtomodelthephasesofmitosis. Askstudentswhatmustoccurbeforeacellcanenteranytypeofcelldivision.Answer:DNAmustbe copiedorreplicatedsothateachcellreceivesacopyofthemasterinstructions. © 2016 HudsonAlpha Institute for Biotechnology 4.DistributeabagcontainingasecondsetofChromoSockstoeachpair(group)ofstudents.Thebag containsthematerialsneededtoreplicatetheChromosocks. 5.Discussreplicatedchromosomes.Studentswillchooseareplicatedchromosomeintheirsketchand labelthefollowing:centromere,chromosomeandchromatid. Introducethevocabularyterms“replicatedchromosome”and“sisterchromatid”.Pointoutthat althoughthereplicatedchromosomecontainstwosisterchromatids,itstillbehavesasasingle chromosomeduringmostofmitosis. 6.Directstudentstomatchthematerialsfromthesecondsetwiththesockchromosomepairsontheir deskfromthefirstbag.Attachpairsofsockswithrubberbandssimulatingtheconnectionbetweensister chromatidsatthecentromere.StudentswillsketchthecellfollowingDNAreplication.Studentswilllabel thechromosomeploidyandnumber.Theywillusean“)(“shapetoindicateeachreplicatedchromosome inthesketches.Studentswillchooseareplicatedchromosomeintheirsketchandlabelthefollowing: centromere,chromosomeandchromatid. Askstudentshowmanychromosomesarepresent.Answer:Six,eachofthereplicatedchromosomesis stillcountedasasinglechromosome.Encouragestudentstocountthenumberofcentromeresrather thanthenumberofsisterchromatidstogetanaccuratechromosomecount. Mitosis 7.ThefollowingstepsillustratehowtousetheChromoSockstomodelmitosis. 8.Atthebeginningofmitosis,thereisonepileofChromoSocksrepresentingthechromosomesinthe nucleusofasinglecell.Directstudentstolineupthepairsalongthemiddleofthedeskortableto representhowchromosomeslineupalongtheequatorofthecell(Metaphase).Studentswillsketchthe chromosomesinthecell. ExplainthatduringMetaphasethespindlefibersareattachedtothecentromereofeachchromosome. Thecentromeresofthesisterchromatidsbehaveindependentlyatthisstep,withaspindlefiberfrom onepoleattachingtothecentromereofonesisterchromatidandthecentromereoftheothersister chromatidattachingtoaspindlefiberfromtheoppositepole. © 2016 HudsonAlpha Institute for Biotechnology 9.Directstudentstoremovetherubberbands,simulatingthephysicalchangeinthecentromerethat allowschromatidstoseparate.Atthispoint,thereplicatedchromosomenolongerbehavesasasingle unit.SeparatethesisterchromatidsbymovingoneofeachoftheChromoSockstotheoppositesideof each‘cell’(Anaphase).Studentswillsketchthechromosomesattheendoftheprocess. Remindstudentsthatoncesisterchromatidsseparate,thechromosomesshouldbesketchedas“I” shapesratherthan“)(”shapes. 10.HavestudentscollecttheChromoSocksintoatightbundlesimulatingthereformingofthenuclear membrane(Telophase). Explainthatcytokinesisoccurs,dividingeachcellintotwonewcells.Askstudentshowmanycellsare formedbythecompletedprocess?Answer:two. 11.Havestudentscarefullycountthenumberofchromosomesineachnewcell.Theywillthensketchthe chromosomesineachcellandlabelthechromosomeploidyandnumberbesideeachsketch. Theyshouldthenanswerthefollowing:Howdoesthechromosomenumbercomparetotheoriginalcell? Howdothetypesofchromosomespresentcomparetotheoriginalcall? Askstudentshowmanychromosomesarefoundineachnewcell?Answer:SixAskhowthesecells comparetotheoriginalcell?Answer:exactlythesameinchromosomenumberandtype. 12.StudentsshouldreplacetheChromoSocksinthebags.Eachbagshouldcontain2long,2mediumand2 shortChromoSocks. CarefullymonitorstudentsastheyreplaceChromoSocksinthebags. © 2016 HudsonAlpha Institute for Biotechnology