有丝分裂和减数分裂(mitosis-and-meosis)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 ThreeyearslaterthesignificanceofChargaff sRulewasrealizebyWatsonandCrickattheCavendishLaboratoryinCambridge England WatsonanAmericangeneticistandCrickanEnglishphysicistbeganmodelbuildingDNAbasedonacollectionofresultsfromotherresearchers includingChargaff 11 FranklinandWilkins WatsonandCrickusedX raycrystallographyfromRosalindFranklinandMauriceWilkinsThemoleculardistancefromAdeninecombinedwithThymineisthesameasthemoleculardistancebetweenGuaninecombinedwithCytosine Thisgaveauniformdistancethatcouldfillthecentreofthehelix 12 DNADoubleHelix 1953 JamesWatsonandFrancisCrickdescribedthedoublehelixstructureofDNA 1958 RosalindFranklindiedattheageof37fromcancer 1962 Watson CrickandWilkinsreceivedtheNobelPrizeinMedicine 13 NucleotideBases Nucleotidesarelinkedtoformasugarphosphatebackbone BasePairing A TC GAlwaysPurine PyrimidineThenitrogenousbasesareheldtogetherbyHydrogenbonds ThenucleotidesareheldtogetherbyCovalent Phosphodiester bonds 14 DNA 15 Thesugarphosphatebackbonewhichprovidesthestablebackboneofoneofthehelices Covalentbondsthatlinkthenucleotidesalonethebackboneofthemolecule Thebasesprojectingintothecenter AToneendthereispentosewith5 carbonwhichisfreefrombonding Attheotherendthereisa3 carbonfreefrombondingtoothernucleotides Thenucleotidesarejoinedatthe3 endofthemolecule 16 DNA 5 DrawandlabelasimplediagramofthemolecularstructureofDNA DoubleHelixAntiparallelStrands 3 5 and5 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 Thenormalbiconcavediscshapeoftheredbloodcellischangedtoa sickle shape 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 StateMendel slawofindependentassortment Allelepairsseparateindependentlyduringtheformationofgametes Thismeansthattraitsaretransmittedtooffspringindependentlyofoneanother 60 61 Meiosis 3 Outlinetheprocessofmeiosis includingpairingofhomologouschromosomesandcrossingover followedbytwodivisions whichresultsinfourhaploidcells 1 10 Describethebehaviorofthechromosomesinthephasesofmeiosis 5 10 ExplaintherelationshipbetweenMendel slawofindependentassortmentandmeiosis 62 MeiosisI 63 ProphaseI NuclearenvelopebreaksdownHomologouschromosomespairupandformtetrads Crossingovermayormaynotoccur 64 CrossingOver 2 10 Outlinetheformationofchiasmataintheprocessofcrossingover Synapsis homologouschromosomespairupandformatetradTetrad 2chromosomesjoinedtogether 4chromatids Crossingover occursintetrads mixingofchromosomes Increasesgeneticdiversity 65 CrossingOver http trc ucdavis edu 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 productionofsperm1spermatid 4spermcells1 4ratio 77 Oogenesis Oogenesis productionofeggs1oocyte 1egg 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 disjunctioncanl