有丝分裂和减数分裂mitosisandmeosis英文版学习资料PPT课件

.,1,3.3,4.1,2.5,4.2,and10.1,DNA,MitosisandMeiosis,.,2,.,3,3.3DNAStructure,OutlineDNAnucleotidestructureintermsofsugar(deoxyribose),baseandphosphate.ThesubunitofDNAisaNucleotide.Nucleotide=Nitrogenbase+Sugar+Phosphategroup,.,4,Nucleotide,.,5,Sugar=Deoxyribosesugar,.,6,ThePhosphategroupisheldtothesugarbyacovalentbond(strongbond),Phosphategroup,.,7,NitrogenousBases,2.StatethenamesofthefourbasesinDNA.AdenineAGuanineGCytosineCThymineT,.,8,Purinesvs.Pyrimidines,Purines(AandG)-2ringsvs.Pyrimidines(TandC)-1ring,PurAsGoldvs.PyCuT,PurinesAdenineGuanine,PyrimidinesCytosineThymine,.,9,NucleotideBases,3.OutlinehowDNAnucleotidesarelinkedtogetherbycovalentbondsintoasinglestrand.4.ExplainhowaDNAdoublehelixisformedusingcomplementarybasepairingandhydrogenbonds.1950EdwinChargaffworkinginColumbiaUniversityUSAhaddeterminedthatthemassofthebasesformedratiosofA:TandG:C.InthecellofanyorganismthemassofAdenineseemstobethesameasthemassofthymine.ThemassofcytosineseemstobethesameasthemassofGuanine.,.,10,WatsonandCrick,ThreeyearslaterthesignificanceofChargaffsRulewasrealizebyWatsonandCrickattheCavendishLaboratoryinCambridge,England.WatsonanAmericangeneticistandCrickanEnglishphysicistbeganmodelbuildingDNAbasedonacollectionofresultsfromotherresearchers,includingChargaff.,.,11,FranklinandWilkins,WatsonandCrickusedX-raycrystallographyfromRosalindFranklinandMauriceWilkinsThemoleculardistancefromAdeninecombinedwithThymineisthesameasthemoleculardistancebetweenGuaninecombinedwithCytosine.Thisgaveauniformdistancethatcouldfillthecentreofthehelix.,.,12,DNADoubleHelix,1953-JamesWatsonandFrancisCrickdescribedthedoublehelixstructureofDNA.1958-RosalindFranklindiedattheageof37fromcancer.1962-Watson,CrickandWilkinsreceivedtheNobelPrizeinMedicine.,.,13,NucleotideBases,Nucleotidesarelinkedtoformasugarphosphatebackbone.BasePairing:A=TCGAlwaysPurine+PyrimidineThenitrogenousbasesareheldtogetherbyHydrogenbonds.ThenucleotidesareheldtogetherbyCovalent(Phosphodiester)bonds,.,14,DNA,.,15,Thesugarphosphatebackbonewhichprovidesthestablebackboneofoneofthehelices.Covalentbondsthatlinkthenucleotidesalonethebackboneofthemolecule.Thebasesprojectingintothecenter.AToneendthereispentosewith5carbonwhichisfreefrombonding.Attheotherendthereisa3carbonfreefrombondingtoothernucleotides.Thenucleotidesarejoinedatthe3endofthemolecule,.,16,DNA,5.DrawandlabelasimplediagramofthemolecularstructureofDNA.DoubleHelixAntiparallelStrands(3-5and5-3),.,17,4.1,Chromosomes,Genes,AllelesandMutations,.,18,EukaryoticChromosomes,1.StatethateukaryotechromosomesaremadeofDNAandHistoneProteins.,.,19,EukaryoticChromosomes,.,20,Gene,Allele,andGenome,2.DefineGene,Allele,andGenome.Gene-composedofDNA,aheritablefactorthatcontrolsaspecificcharacteristic,itcodesforproteins.Allele-onespecificformofagene,differingfromotherallelesbyoneorafewbasesonlyandoccupyingthesamegenelocusasotherallelesofthatgene.Genome-thewholegeneticinformationoftheorganism.,.,21,GeneMutation,3.DefineGeneMutation.GeneMutation-isachangeinthebasesequenceofanallele.Thechangemayproduceadifferentaminoacidsequenceintheproteintranslated.ThechangemaynotchangetheproteinbecauseofthedegeneratenatureofthegeneticcodeTheexpressionofthemutatedgenemayormaynotbebeneficialtotheorganism.Substancesthatcausemutationsarecalledmutagensandincludechemicalsandradiation.,.,22,TypesofGeneMutations,.,23,BaseSubstitutionMutations,4.Explaintheconsequencesofabasesubstitutionmutationinrelationtotheprocessesoftranscriptionandtranslation,usingtheexampleofsickle-cellanemia.SickleCellAnemiaisageneticdiseaseItoccursinabout1in655AfricanAmericansThediseaseisinheritednotcontractedbyinfectionsroutes.,.,24,SickleCellAnemia,Normalhemoglobinhas2of4proteinschangedinthemutation.Thenormalbiconcavediscshapeoftheredbloodcellischangedtoasickleshape.Inadditiontonotcarryingoxygencorrectlythecellsalsocauselocalclots(shownhereinthekidneytubule).Thisleadstonecrosis(death)ofthetubules,kidneydamage,failureandpossibledeath.,.,25,SickleCellAnemia,Thegenelocifornormalbetachainofhemoglobinisonchromosome11.ThenormalallelecarriedthecodonGAGatthe6thaminoacidposition,forthebetachain(146A.A.)ThistranscribedandtranslatesintothenegativelychargedGlutamicAcid.,.,26,SickleCellAnemia,Themutationchangesasinglebase(TreplacesA)andthistranscribesandtranslatesintoValine.Valinehasaneutralchargeandtheresultisachangeintheshapeofthebetachainwithlongneedlelikestructuresforming.Thisgeneisnotedformmanymutationsanditisestimatedthatsome5%ofhumanscarryoneorothervariants.,.,27,SickleCellAnemia,.,28,SickleCellAnemia,Thisisamapofthedistributionofendemicfalciparummalaria.ThemajorareasaretheMediterranean,tropicalAfrica,middleeaseandAsia.,.,29,SickleCellAnemia,ThisisamapofthedistributionofthesicklecellalleleHbs.TheregionsnotedashavingahighfrequencyofHbsarethesameastheregionsnotedformalaria.,.,30,SickleCellAnemia,Thereappearstobeacorrelationbetweenthedistributionofmalariaandthefrequencyofthesicklecellallele.Thequestionthereforeis:Isthisjustcorrelationoristhereacausation?,.,31,SickleCellAnemia,Thereisawellestablishedcausationthebetweensicklecellalleleandthedistributionofmalaria.,.,32,SickleCellAnemia,Intheseregionssicklecelltrait(HbAHbS)areresistanttothemalariaparasite.ThisisbecausetheHbSallelemakesitdifficultforthemalariaparasite(Plasmodium)toliveinsidetheredcells.Thereforethesicklecellcarrierssurvivemalariainfections.HbAHbAnormalhemoglobinpeoplearesusceptibletomalariainfectionsanddonothaveahighsurvivalrate.HbSHbshavesicklecellanddonotsurvivalwelleither.,.,33,2.5CellDivision,.,34,CellCycle,1.Outlinethestatesinthecellcycle,includinginterphase(G1,S,G2),Mitosis,andcytokinesis.CellCycle-repeatingsetofeventsthatmakeupthelifeofacell,.,35,CellCycle,Interphase-G1,S,andG2-timebetweencelldivisionsG1Phase-Cellgrowsandmatures,itperformsitsnormaldifferentiatedfunctions:proteinsynthesis,respiration,glycolysis,transcriptionSPhase-DNAreplicationG2Phase-Cellpreparesfordivision,mitochondria/chloroplastreplicationMphase-Mitosis-nucleusdividesCytokinesis-cytoplasmdividestoform2cellsG0Phase-ExitsCellcycle-DoesnotdivideorcopyDNA(notpartofthecellcycle),.,36,Cancer-Tumors,2.Statethattumors(cancers)aretheresultofuncontrolledcelldivisionandthatthesecanoccurinanyorganortissue.Apoptosis-“programmedcelldeath”Cellshaveapre-programmed(genetic)lifespanandareproductionrate,ifthegenesthatcontroltheseprocessesmutatetumorscanform.(Oncogenes),.,37,Interphase,3.StatethatInterphaseisanactiveperiodinthelifeofacellwhenmanymetabolicreactionsoccur,includingproteinsynthesis,DNAreplicationandanincreaseinthenumberofmitochondriaand/orchloroplasts.,.,38,Mitosis,4.Describetheeventsthatoccurinthefourphasesofmitosis(prophase,metaphase,anaphase,andtelophase).Includesupercoilingofchromosomes,attachmentofspindlemicrotubulestocentromeres,splittingofcentromeres,movementofsisterchromosomestooppositepoles,andbreakageandre-formationofnuclearmembranes.5.Explainhowmitosisproducestwogeneticallyidenticalnuclei.Mitosis-divisionofNucleus“CopyMachine”,.,39,Chromosomes,Haploid-1n-onecopyofeverychromosome1n=23forhumansOnlyspermandeggDiploid-2n-twocopiesofeverychromosome(pairsofhomologouschromosomes)2n=46forhumansAllcellsexceptgametes,.,40,Mitosis,2n=44Chromosomes8sister2cellseachwithchromosomes4chromosomes2n=4,.,41,Mitosis,Prophase-nucleusdisappearsandchromatincondensesintochromosomes(supercoiling)Centrosomes-darkspotsnexttodisappearingnucleusCentrioles-producespindlemicrotubules-onlyinanimalsSpindlemicrotubules-attachtochromosomes,.,42,SuperCoiling,Supercoiling:EukaryoticDNAiscombinedwithhistoneproteinsandnon-histoneproteinstoformthereadilystainablechromatin.Themethodoffoldingofchromatinisspecifictoeachchromosomeleavinggenesinpredictablepositionsandadistinctiveoverallchromosomeshape.ThehumancellhasaDNAlengthofabout1.8mthishastobepackedintoanucleuswhichhasonlya10umdiameter.ThispackagingprocessrequiresuptoaX15,000reduction.Thissupercoilingmakesthestructuresodensethatitcanbeseewithalightmicroscopeduringthephasesofmitosis.,.,43,Prophase,.,44,Mitosis,Metaphase-chromosomeslineupattheequator,.,45,Metaphase,.,46,Mitosis,Anaphase-sisterchromosomesseparateandmovetooppositepoles,.,47,Anaphase,.,48,Mitosis,Telophase-Chromosomesstarttoreturntochromatinandnucleusstartstoreform,.,49,Telophase,.,50,Cytokinesis,Cytokinesis-divisionofthecytoplasm2identicaldaughtercellsareformed,.,51,Cytokinesis,Cleavagefurrow-areaofcellmembranethatpinchesanddividesinto2Cellplate-onlyinplants-membraneboundcellwallthatmustpinchoffinto2also,Animalcell,Plantcell,.,52,.,53,Mitosis,6.Statethatgrowth,embryonicdevelopment,tissuerepairandasexualreproductioninvolvemitosis.Growthandembryonicdevelopment-thisinvolvesincreasingthenumberofdifferentiatedcellsTissuerepair-deadordamagedcellsarereplacedbynewcells(cutonyourskin)Asexualreproduction-Bacteria,clones,.,54,4.2and10.1,Meiosis,.,55,.,56,Meiosis,1.Statethatmeiosisisareductiondivisionofadiploidnucleustoformhaploidnuclei.,.,57,Meiosis,(a)ThecellisinG1oftheinterphaseandhasatotalof2chromosomes,2n=2.(b)TheSphaseoftheinterphaseisDNAreplication.(c)InG2oftheinterphasethecellhastwodaughterchromatidsperchromosome,thecellmassofDNAhasdoubled.(d)Meiosisoccursinaseriesofphasessimilartomitosisbutwithsignificantdifferences.(e)Thediploidcellhasdividedtoformhaploidgametecells(n=1).(f)Thehomologouspairofchromosomeshasbeenseparated(redfromblue).Onediploidcellwhichundergoesmeiosisproducesfourhaploidgameticcells.,.,58,HomologousChromosomes,2.DefineHomologousChromosomes.Apairofchromosomescontainingthesamegenesequences,thatarethesamelengthandshape;eachderivedfromoneparent.Theycontainthesamegenesthoughmaypossessdifferingalleles.,.,59,LawofIndependentAssortment,4.(10)StateMendelslawofindependentassortment.Allelepairsseparateindependentlyduringtheformationofgametes.Thismeansthattraitsaretransmittedtooffspringindependentlyofoneanother.,.,60,.,61,Meiosis,3.Outlinetheprocessofmeiosis,includingpairingofhomologouschromosomesandcrossingover,followedbytwodivisions,whichresultsinfourhaploidcells.1.(10)Describethebehaviorofthechromosomesinthephasesofmeiosis.5.(10)ExplaintherelationshipbetweenMendelslawofindependentassortmentandmeiosis.,.,62,MeiosisI,.,63,ProphaseI,NuclearenvelopebreaksdownHomologouschromosomespairupandformtetrads.Crossingovermayormaynotoccur.,.,64,CrossingOver,2.(10)Outlinetheformationofchiasmataintheprocessofcrossingover.Synapsis-homologouschromosomespairupandformatetradTetrad-2chromosomesjoinedtogether(4chromatids)Crossingover-occursintetrads,mixingofchromosomes-Increasesgeneticdiversity,.,65,CrossingOver,/biosci10v/bis10v/media/ch07/crossover.html,.,66,Meiosis,3.(10)ExplainhowmeiosisresultsinaneffectivelyinfinitegeneticvarietyingametesthroughcrossingoverinprophaseIandrandomorientationinmetaphaseI.IndependentassortmentleadstotherandomaligningofhomologouschromosomesWithoutcrossingoverthereare223differenttypesofgametesCrossingoverleadstonewcombinationsofallelesWithcrossingoverthereareaninfinitenumberofgametecombinations,.,67,MetaphaseI,Pairsofhomologouschromosomeslineupattheequator,.,68,AnaphaseI,Homologouschromosomesseparateandmovetooppositepoles,.,69,TelophaseI,Homologouschromosomesgatheratoppositepolesandcytoplasmdivides.,.,70,MeiosisII,MeiosisII-endupwith4haploidcells,.,71,ProphaseII,Newspindlesformaroundthechromosomes,.,72,MetaphaseII,Chromosomeslineupattheequator,.,73,AnaphaseII,Chromosomesseparate,nowformingsisterchromosomesthatmovetowardsoppositepoles.,.,74,TelophaseII,Chromosomesclusteratthepolesandthenuclearenvelopebeginstoformaroundeachsetofchromosomes,.,75,Cytokinesis,Cytoplasmdividesandresultsin4haploidcells.,.,76,Spermatogenesis,Spermatogenesis-productionofsperm1spermatid4spermcells1:4ratio,.,77,Oogenesis,Oogenesis-productionofeggs1oocyte1egg+2polarbodies1:1ratiounequalcytokinesis,.,78,.,79,Mitosisvs.Meiosis,.,80,Mitosisvs.Meiosis,ChromosomebehaviorinMeiosisIIissimilartoMitosis.ChromosomebehaviorinMeiosisIisdifferentthanMitosis.Meiosisincreasesgeneticvariation,Mitosismakescopiesofcells.,.,81,Karyotyping,5.Statethat,inkaryotyping,chromosomesarearrangedinpairsaccordingtotheirsizeandstructure.Picturescanbetakenofthehumanchromosomesduringthemetaphase.Theycanthenbearrangedintopairsonthebasisoflength,shape,centromerepositionandstainingpattern.Thechromosomesappearaspairsofsisterchromatids.,.,82,Karyotyping,6.Statethatkaryotypingisperformedusingcellscollectedbychorionicvillussamplingoramniocentesis,forpre-nataldiagnosisofchromosomeabnormalities.Pre-natalmeansbeforebirthDiagnosismeanstodecideorfindoutwhatkindofdiseaseorconditionmayexist.Pre-nataldiagnosisiswhenmethodsareusedtodetermineifanunbornchildissufferingfromadiseaseorabnormalcondition.,.,83,Karyotyping,Amniocentesisandchorionicvillussamplingarethetwomainmethodsofobtainingtissuesamplesforpre-nataldiagnosis.Bothtechniquestakeadvantageofthefactthatembryonicmembranes,chorion,amnionandplacentaarebothderivedformtheembryonotthemother.Thecellsofthesemembraneshaveexactlythesamegenotype/genome(DNA)astheembryo.,.,84,Karyotype,7.Analyzeahumankaryotypetodeterminethegenderandwhethernondisjunctionhasoccurred.,.,85,Karyotyping,.,86,Karyotyping,Thereare23pairs(46chromosomes)thereforethisishumanInthiscasethe23rdpairinthiscaseareonelongpairofchromatids(X-chromosome)andoneveryshort(Ychromosome).Thisisamalehuman.Thereisnovisiblechromosomalabnormality.,.,87,Karyotype,NormalFemale,.,88,Non-Disjunction,4.Explainthatnon-disjunctioncan