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Chapter 10
- 2. 2 Cell DivisionCell Division All cells are derived fromAll cells are derived from pre-pre- existingexisting cellscells New cells are produced forNew cells are produced for growthgrowth and to replaceand to replace damaged ordamaged or old cellsold cells Differs inDiffers in prokaryotesprokaryotes (bacteria)(bacteria) andand eukaryoteseukaryotes (protists, fungi,(protists, fungi, plants, & animals)plants, & animals)
- 3. 3 Keeping Cells IdenticalKeeping Cells Identical TheThe instructions forinstructions for making cell partsmaking cell parts are encoded in theare encoded in the DNADNA, so each new, so each new cell must get acell must get a complete set of thecomplete set of the DNA moleculesDNA molecules
- 4. 4 DNA ReplicationDNA Replication DNA must beDNA must be copied orcopied or replicatedreplicated before cellbefore cell divisiondivision Each new cellEach new cell will then have anwill then have an identical copyidentical copy ofof the DNAthe DNA Original DNAOriginal DNA strandstrand Two new,Two new, identical DNAidentical DNA strandsstrands
- 5. 5 Identical Daughter CellsIdentical Daughter Cells Parent CellParent Cell TwoTwo identicalidentical daughterdaughter cellscells
- 7. 7 Prokaryotic ChromosomeProkaryotic Chromosome The DNA ofThe DNA of prokaryotesprokaryotes (bacteria) is(bacteria) is one,one, circularcircular chromosomechromosome attached to theattached to the inside of the cellinside of the cell membranemembrane
- 8. 8 Eukaryotic ChromosomesEukaryotic Chromosomes AllAll eukaryoticeukaryotic cells store geneticcells store genetic information in chromosomesinformation in chromosomes Most eukaryotes have betweenMost eukaryotes have between 10 and10 and 50 chromosomes50 chromosomes in their body cellsin their body cells Human body cellsHuman body cells havehave 4646 chromosomeschromosomes or 23 identical pairsor 23 identical pairs
- 9. 9 Eukaryotic ChromosomesEukaryotic Chromosomes Each chromosome is composed of aEach chromosome is composed of a single,single, tightly coiled DNAtightly coiled DNA moleculemolecule ChromosomesChromosomes cancan’’t be seent be seen whenwhen cellscells arenaren’’t dividingt dividing and are calledand are called chromatinchromatin
- 10. 10 Compacting DNA intoCompacting DNA into ChromosomesChromosomes DNA is tightly coiled around proteins called histones
- 11. 11 Chromosomes in Dividing CellsChromosomes in Dividing Cells Duplicated chromosomes are called chromatids & are held together by the centromere Called Sister ChromatidsCalled Sister Chromatids
- 12. 12 KaryotypeKaryotype AA picturepicture of theof the chromosomes from achromosomes from a human cellhuman cell arrangedarranged in pairs by sizein pairs by size First 22 pairs areFirst 22 pairs are calledcalled autosomesautosomes Last pair are theLast pair are the sex chromosomessex chromosomes XXXX female orfemale or XYXY malemale
- 13. 13 Boy or Girl?Boy or Girl? Y - ChromosomeY - Chromosome X - ChromosomeX - Chromosome The Y Chromosome DecidesThe Y Chromosome Decides
- 15. 15 Types of Cell ReproductionTypes of Cell Reproduction Asexual reproductionAsexual reproduction involves ainvolves a single cellsingle cell dividing to makedividing to make 2 new,2 new, identical daughter cellsidentical daughter cells Mitosis & binary fissionMitosis & binary fission areare examples of asexual reproductionexamples of asexual reproduction Sexual reproductionSexual reproduction involves twoinvolves two cells (egg & sperm) joining to make acells (egg & sperm) joining to make a new cell (zygote)new cell (zygote) that isthat is NOTNOT identical to the original cellsidentical to the original cells MeiosisMeiosis is an exampleis an example
- 16. 16 Cell Division inCell Division in ProkaryotesProkaryotes
- 17. 17 Cell Division in ProkaryotesCell Division in Prokaryotes Prokaryotes such asProkaryotes such as bacteriabacteria divide into 2divide into 2 identical cells by theidentical cells by the process ofprocess of binarybinary fissionfission Single chromosomeSingle chromosome makes a copy ofmakes a copy of itselfitself Cell wall formsCell wall forms between thebetween the chromosomes dividingchromosomes dividing the cellthe cell ParentParent cellcell 2 identical daughter cells2 identical daughter cells ChromosomeChromosome doublesdoubles Cell splitsCell splits
- 18. 18 Prokaryotic CellProkaryotic Cell Undergoing Binary FissionUndergoing Binary Fission
- 19. 19 Animation of Binary FissionAnimation of Binary Fission
- 21. 21 Five Phases of the Cell CycleFive Phases of the Cell Cycle GG11 - primary growth phase- primary growth phase S – synthesis; DNA replicatedS – synthesis; DNA replicated GG22 - secondary growth phase- secondary growth phase collectively these 3 stages arecollectively these 3 stages are called interphasecalled interphase M - mitosisM - mitosis C - cytokinesisC - cytokinesis
- 23. 23 Interphase - GInterphase - G11 StageStage 11stst growth stagegrowth stage after cellafter cell divisiondivision CellsCells maturemature by making moreby making more cytoplasm & organellescytoplasm & organelles Cell carries on itsCell carries on its normalnormal metabolic activitiesmetabolic activities
- 24. 24 Interphase – S StageInterphase – S Stage SynthesisSynthesis stagestage DNADNA is copied oris copied or replicatedreplicated TwoTwo identicalidentical copiescopies of DNAof DNA OriginalOriginal DNADNA
- 25. 25 Interphase – GInterphase – G22 StageStage 22ndnd GrowthGrowth StageStage OccursOccurs after DNA has been copiedafter DNA has been copied All cellAll cell structures needed forstructures needed for divisiondivision are made (e.g. centrioles)are made (e.g. centrioles) BothBoth organelles & proteinsorganelles & proteins areare synthesizedsynthesized
- 26. 26 WhatWhat’’s Happening in Interphase?s Happening in Interphase? What the cell looks likeWhat the cell looks like Animal Cell What’s occurring
- 27. 27 Sketch the Cell CycleSketch the Cell Cycle DaughterDaughter CellsCells DNA CopiedDNA Copied CellsCells MatureMature Cells prepare forCells prepare for DivisionDivision Cell Divides intoCell Divides into Identical cellsIdentical cells
- 29. 29 MitosisMitosis Division of theDivision of the nucleusnucleus Also calledAlso called karyokinesiskaryokinesis Only occurs inOnly occurs in eukaryoteseukaryotes HasHas fourfour stagesstages DoesnDoesn’’t occur int occur in some cells suchsome cells such asas brain cellsbrain cells
- 30. 30 Four Mitotic StagesFour Mitotic Stages ProProphasephase MetaMetaphasephase AnaAnaphasephase TeloTelophasephase
- 31. 31 Early ProphaseEarly Prophase ChromatinChromatin in nucleus condenses toin nucleus condenses to formform visible chromosomesvisible chromosomes Mitotic spindleMitotic spindle forms from fibers informs from fibers in cytoskeleton orcytoskeleton or centrioles (animal)centrioles (animal) ChromosomesChromosomes NucleolusNucleolus CytoplasmCytoplasm Nuclear MembraneNuclear Membrane
- 32. 32 Late ProphaseLate Prophase Nuclear membrane & nucleolusNuclear membrane & nucleolus areare broken downbroken down ChromosomesChromosomes continue condensing &continue condensing & areare clearly visibleclearly visible Spindle fibers calledSpindle fibers called kinetochoreskinetochores attach to the centromereattach to the centromere of eachof each chromosomechromosome SpindleSpindle finishes forming between thefinishes forming between the poles of the cellpoles of the cell
- 33. 33 Late ProphaseLate Prophase Nucleus & Nucleolus have disintegratedNucleus & Nucleolus have disintegrated ChromosomesChromosomes
- 34. 34 Spindle Fiber attached toSpindle Fiber attached to ChromosomeChromosome Kinetochore FiberKinetochore Fiber ChromosomeChromosome
- 35. 35 Review of ProphaseReview of Prophase What the cellWhat the cell looks likelooks like WhatWhat’’s happenings happening
- 36. 36 Spindle FibersSpindle Fibers The mitoticThe mitotic spindlespindle form from theform from the microtubulesmicrotubules in plantsin plants andand centriolescentrioles in animal cellsin animal cells Polar fibersPolar fibers extend from one pole ofextend from one pole of the cell to the opposite polethe cell to the opposite pole Kinetochore fibersKinetochore fibers extend from theextend from the pole to the centromere of thepole to the centromere of the chromosome to which they attachchromosome to which they attach AstersAsters are short fibers radiatingare short fibers radiating from centriolesfrom centrioles
- 37. 37 Sketch The SpindleSketch The Spindle
- 38. 38 MetaphaseMetaphase Chromosomes, attached to theChromosomes, attached to the kinetochore fiberskinetochore fibers, move to the center, move to the center of the cellof the cell Chromosomes are now lined up at theChromosomes are now lined up at the equatorequator Pole ofPole of the Cellthe Cell Equator of CellEquator of Cell
- 39. 39 MetaphaseMetaphase ChromosomesChromosomes lined at thelined at the EquatorEquator Asters atAsters at the polesthe poles SpindleSpindle FibersFibers
- 41. 41 Review of MetaphaseReview of Metaphase What the cell looksWhat the cell looks likelike WhatWhat’’ss occurringoccurring
- 42. 42 AnaphaseAnaphase OccursOccurs rapidlyrapidly SisterSister chromatidschromatids areare pulled apart topulled apart to opposite polesopposite poles of the cell byof the cell by kinetochorekinetochore fibersfibers
- 44. 44 Anaphase ReviewAnaphase Review What theWhat the cell lookscell looks likelike WhatWhat’’ss occurringoccurring
- 45. 45 TelophaseTelophase Sister chromatids atSister chromatids at oppositeopposite polespoles SpindleSpindle disassemblesdisassembles Nuclear envelopeNuclear envelope forms aroundforms around each set of sister chromatidseach set of sister chromatids NucleolusNucleolus reappearsreappears CYTOKINESISCYTOKINESIS occursoccurs Chromosomes reappear asChromosomes reappear as chromatinchromatin
- 46. 46 Comparison of Anaphase & TelophaseComparison of Anaphase & Telophase
- 47. 47 CytokinesisCytokinesis Means division of the cytoplasmMeans division of the cytoplasm DivisionDivision of cell into two,of cell into two, identical halves calledidentical halves called daughterdaughter cellscells In plant cells, cell plateIn plant cells, cell plate formsforms at the equator to divide cellat the equator to divide cell In animal cells,In animal cells, cleavage furrowcleavage furrow forms to split cellforms to split cell
- 48. 48 CytokinesisCytokinesis Cleavage furrowCleavage furrow in animal cellin animal cell Cell plate inCell plate in animal cellanimal cell
- 50. 50 Daughter Cells of MitosisDaughter Cells of Mitosis Have theHave the same number ofsame number of chromosomes as each otherchromosomes as each other and asand as the parent cellthe parent cell from which theyfrom which they were formedwere formed IdenticalIdentical to each other, butto each other, but smallersmaller than parent cellthan parent cell MustMust grow in sizegrow in size to become matureto become mature cellscells (G(G11 of Interphase)of Interphase)
- 51. 51 Identical Daughter CellsIdentical Daughter Cells Chromosome number theChromosome number the samesame, but cells, but cells smallersmaller than parent cellthan parent cell What isWhat is the 2nthe 2n oror diploiddiploid number?number? 22
- 53. 53 Draw & Learn these StagesDraw & Learn these Stages
- 54. 54 Draw & Learn these StagesDraw & Learn these Stages
- 55. 55 InterphaseInterphase ProphaseProphase MetaphaseMetaphase AnaphaseAnaphase TelophaseTelophase Name the Mitotic Stages:Name the Mitotic Stages: Name this?Name this? Name this?Name this?
- 56. 56 Eukaryotic Cell DivisionEukaryotic Cell Division Used forUsed for growth andgrowth and repairrepair Produce two new cellsProduce two new cells identical to the originalidentical to the original cellcell Cells areCells are diploid (2n)diploid (2n) Chromosomes duringChromosomes during Metaphase of mitosisMetaphase of mitosis ProphaseProphase MetaphaseMetaphase AnaphaseAnaphase TelophaseTelophase CytokinesisCytokinesis
- 57. 57 Mitosis AnimationMitosis Animation Name each stage as you see it occur?Name each stage as you see it occur?
- 58. 58 Mitosis in Onion Root TipsMitosis in Onion Root Tips Do you see any stages of mitosis?Do you see any stages of mitosis?
- 59. 59 Test YourselfTest Yourself over Mitosisover Mitosis
- 62. 62 Name the Stages of Mitosis:Name the Stages of Mitosis: Interphase Early prophase Mid-Prophase Late Prophase Metaphase Late Anaphase Early Anaphase Early Telophase, Begin cytokinesis Late telophase, Advanced cytokinesis
- 63. 63 Identify the StagesIdentify the Stages Early, Middle, & Late ProphaseEarly, Middle, & Late Prophase Late ProphaseLate Prophase MetaphaseMetaphase AnaphaseAnaphase Late AnaphaseLate Anaphase TelophaseTelophase Telophase &Telophase & CytokinesisCytokinesis ?? ?? ?? ?? ?? ?? ??
- 64. 64 Locate the Four MitoticLocate the Four Mitotic Stages in PlantsStages in Plants MetaphaseMetaphase ProphaseProphase AnaphaseAnaphase TelophaseTelophase
- 65. 65 Uncontrolled Mitosis If mitosis is notIf mitosis is not controlledcontrolled, unlimited, unlimited cell division occurscell division occurs causing cancerouscausing cancerous tumorstumors OncogenesOncogenes are specialare special proteinsproteins that increase the chanceincrease the chance that a normal cellthat a normal cell develops into adevelops into a tumortumor cellcell Cancer cellsCancer cells
- 66. 66 MeiosisMeiosis Formation of GametesFormation of Gametes (Eggs & Sperm)(Eggs & Sperm)
- 67. 67 Facts About MeiosisFacts About Meiosis Preceded by interphase whichPreceded by interphase which includesincludes chromosome replicationchromosome replication TwoTwo meiotic divisions ---meiotic divisions --- MeiosisMeiosis I and Meiosis III and Meiosis II Called Reduction- divisionCalled Reduction- division Original cell is diploid (2n)Original cell is diploid (2n) Four daughter cellsFour daughter cells produced thatproduced that areare monoploid (1n)monoploid (1n)
- 68. 68 Facts About MeiosisFacts About Meiosis Daughter cellsDaughter cells contain half thecontain half the number of chromosomesnumber of chromosomes as theas the original celloriginal cell ProducesProduces gametesgametes (eggs & sperm(eggs & sperm)) Occurs in theOccurs in the testestestes in malesin males ((SpermatogenesisSpermatogenesis)) Occurs in theOccurs in the ovariesovaries in femalesin females ((OogenesisOogenesis))
- 69. 69 Start withStart with 46 double stranded46 double stranded chromosomes (2n)chromosomes (2n) After 1 division -After 1 division - 23 double23 double stranded chromosomes (n)stranded chromosomes (n) After 2nd division -After 2nd division - 23 single23 single stranded chromosomes (n)stranded chromosomes (n) Occurs in ourOccurs in our germ cellsgerm cells thatthat produce gametesproduce gametes More Meiosis FactsMore Meiosis Facts
- 70. 70 Why Do we Need Meiosis?Why Do we Need Meiosis? It is the fundamental basis ofIt is the fundamental basis of sexual reproductionsexual reproduction Two haploid (1n) gametes areTwo haploid (1n) gametes are brought together throughbrought together through fertilizationfertilization to form a diploidto form a diploid (2n) zygote(2n) zygote
- 71. 71 Fertilization –Fertilization – ““Putting itPutting it all togetherall together”” 1n =31n =3 2n = 62n = 6
- 72. 72 Replication of ChromosomesReplication of Chromosomes ReplicationReplication is theis the process ofprocess of duplicating aduplicating a chromosomechromosome OccursOccurs prior toprior to divisiondivision Replicated copiesReplicated copies are calledare called sistersister chromatidschromatids Held together atHeld together at centromerecentromere Occurs inOccurs in InterphaseInterphase
- 73. 73 A Replicated ChromosomeA Replicated Chromosome HomologsHomologs (same genes,(same genes, different alleles)different alleles) SisterSister ChromatidsChromatids (same genes,(same genes, same alleles)same alleles) Gene XGene X Homologs separate in meiosis I andHomologs separate in meiosis I and therefore different alleles separate.therefore different alleles separate.
- 74. 74 Meiosis Forms Haploid GametesMeiosis Forms Haploid Gametes Meiosis mustMeiosis must reduce the chromosome numberreduce the chromosome number by halfby half Fertilization then restoresFertilization then restores the 2n numberthe 2n number from mom from dad child meiosis reduces genetic content too much! The right number!
- 75. 75 Meiosis: Two Part CellMeiosis: Two Part Cell DivisionDivision HomologsHomologs separateseparate SisterSister chromatidschromatids separateseparate DiploidDiploid MeiosisMeiosis II MeiosisMeiosis IIII DiploidDiploid HaploidHaploid
- 76. 76 Meiosis I: Reduction DivisionMeiosis I: Reduction Division NucleusNucleus SpindleSpindle fibersfibers NuclearNuclear envelopeenvelopeEarlyEarly Prophase IProphase I (Chromosome(Chromosome numbernumber doubleddoubled)) LateLate ProphaseProphase II MetaphaseMetaphase II AnaphaseAnaphase II Telophase ITelophase I (diploid)(diploid)
- 77. 77 Prophase IProphase I Early prophaseEarly prophase Homologs pair.Homologs pair. Crossing overCrossing over occursoccurs. Late prophaseLate prophase Chromosomes condense.Chromosomes condense. Spindle forms.Spindle forms. Nuclear envelopeNuclear envelope fragments.fragments.
- 78. 78 Tetrads Form in Prophase ITetrads Form in Prophase I Homologous chromosomesHomologous chromosomes (each with sister chromatids)(each with sister chromatids) Join to form aJoin to form a TETRADTETRAD Called SynapsisCalled Synapsis
- 79. 79 Crossing-OverCrossing-Over HomologousHomologous chromosomeschromosomes inin a tetrada tetrad crosscross over each otherover each other Pieces ofPieces of chromosomes orchromosomes or genes aregenes are exchangedexchanged ProducesProduces GeneticGenetic recombinationrecombination inin the offspringthe offspring
- 80. 80 Homologous ChromosomesHomologous Chromosomes During Crossing-OverDuring Crossing-Over
- 81. 81 Crossing-over multiplies the already hugeCrossing-over multiplies the already huge number of different gamete typesnumber of different gamete types produced by independent assortmentproduced by independent assortment Crossing-OverCrossing-Over
- 82. 82 Metaphase IMetaphase I Homologous pairsHomologous pairs of chromosomesof chromosomes align along thealign along the equatorequator of theof the cellcell
- 83. 83 Anaphase IAnaphase I Homologs separateHomologs separate andand move to opposite poles.move to opposite poles. Sister chromatidsSister chromatids remainremain attachedattached at theirat their centromerescentromeres.
- 84. 84 Telophase ITelophase I Nuclear envelopesNuclear envelopes reassemble.reassemble. Spindle disappears.Spindle disappears. CytokinesisCytokinesis divides celldivides cell into two.into two.
- 85. 85 Meiosis IIMeiosis II Only one homolog of eachOnly one homolog of each chromosome is present inchromosome is present in the cellthe cell. Meiosis II produces gametes withMeiosis II produces gametes with one copy of each chromosome andone copy of each chromosome and thus one copy of each gene.thus one copy of each gene. Sister chromatids carrySister chromatids carry identical geneticidentical genetic informationinformation.. Gene XGene X
- 86. 86 Meiosis II: ReducingMeiosis II: Reducing Chromosome NumberChromosome Number ProphaseProphase IIII MetaphaseMetaphase IIII AnaphaseAnaphase IIII TelophaseTelophase IIII 4 Identical4 Identical haploid cellshaploid cells
- 87. 87 Prophase IIProphase II Nuclear envelopeNuclear envelope fragments.fragments. Spindle forms.Spindle forms.
- 88. 88 Metaphase IIMetaphase II Chromosomes alignChromosomes align alongalong equatorequator of cellof cell..
- 89. 89 Anaphase IIAnaphase II Sister chromatidsSister chromatids separate andseparate and move tomove to oppositeopposite polespoles. EquatorEquator PolePole
- 90. 90 Telophase IITelophase II Nuclear envelopeNuclear envelope assembles.assembles. ChromosomesChromosomes decondense.decondense. Spindle disappears.Spindle disappears. Cytokinesis dividesCytokinesis divides cell into two.cell into two.
- 91. 91 Results of MeiosisResults of Meiosis Gametes (egg & sperm)Gametes (egg & sperm) formform Four haploid cells withFour haploid cells with one copy of eachone copy of each chromosomechromosome One allele of each geneOne allele of each gene Different combinations ofDifferent combinations of alleles for differentalleles for different genes along thegenes along the chromosomechromosome
- 93. 93 SpermatogenesisSpermatogenesis Occurs in theOccurs in the testestestes Two divisionsTwo divisions produce 4produce 4 spermatidsspermatids SpermatidsSpermatids maturemature into sperminto sperm Men produce aboutMen produce about 250,000,000250,000,000 sperm per daysperm per day
- 94. 94 Spermatogenesis in theSpermatogenesis in the TestesTestes SpermatidSpermatid
- 96. 96 OogenesisOogenesis Occurs in theOccurs in the ovariesovaries Two divisions produceTwo divisions produce 3 polar bodies3 polar bodies that die andthat die and 1 egg1 egg Polar bodies die because ofPolar bodies die because of unequalunequal division of cytoplasmdivision of cytoplasm Immature egg calledImmature egg called oocyteoocyte Starting at puberty, one oocyteStarting at puberty, one oocyte matures into anmatures into an ovum (egg)ovum (egg) every 28every 28 daysdays
- 97. 97 Oogenesis in the OvariesOogenesis in the Ovaries
- 98. 98 OogenesisOogenesis OogoniumOogonium (diploid)(diploid) MitosisMitosis PrimaryPrimary oocyteoocyte (diploid)(diploid) Meiosis IMeiosis I SecondarySecondary oocyteoocyte (haploid)(haploid) Meiosis IIMeiosis II (if fertilization(if fertilization occurs)occurs) First polar bodyFirst polar body may dividemay divide (haploid)(haploid) PolarPolar bodiesbodies diedie Ovum (egg)Ovum (egg) SecondSecond polar bodypolar body (haploid)(haploid) a A X X a X A X a X a X MatureMature eggegg A X A X
- 100. 100 MitosisMitosis MeiosisMeiosis Number ofNumber of divisionsdivisions 11 22 Number ofNumber of daughter cellsdaughter cells 22 44 GeneticallyGenetically identical?identical? YesYes NoNo Chromosome #Chromosome # Same as parentSame as parent Half of parentHalf of parent WhereWhere Somatic cellsSomatic cells Germ cellsGerm cells WhenWhen Throughout lifeThroughout life At sexual maturityAt sexual maturity RoleRole Growth andGrowth and repairrepair Sexual reproductionSexual reproduction Comparison of DivisionsComparison of Divisions
- 101. 101
Notes de l'éditeur
- Replication is the process of duplicating chromosome. The new copy of a chromosome is formed by DNA synthesis during S-phase. The chromosome copies are called sister chromatids. Sister chromatids are held together at the centromere.