Sanjay kumar
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The cell cycle is a process of growth and division in cells, leading to asexual (mitosis, binary fission) and sexual (meiosis) reproduction. It includes phases such as interphase (growth and DNA replication), mitosis (nuclear division), and cytokinesis (cytoplasm division). Mitosis results in two genetically identical daughter cells, while meiosis produces four haploid gametes, crucial for sexual reproduction.
Sanjay kumar
- 2. The Cell Cycle Submitted To Submitted By
- 3. What is Cell cycle The cell cycle is a process in which a cell grows and divides to create a copy of itself. o All cells are derived from pre-existing cells. o New cells are produced for growth and to replace damaged or old cells o Differs in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals)
- 5. Types of Cell Reproduction o Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells o Mitosis & binary fission are examples of asexual reproduction o Sexual reproduction involves two cells (egg & sperm) joining to make a new cell (zygote) that is NOT identical to the original cells o Meiosis is an example
- 6. Cell Division in Prokaryotes
- 7. Cell Division in Prokaryotes o Prokaryotes such as bacteria divide into 2 identical cells by the process of binary fission o Single chromosome makes a copy of itself o Cell wall forms between the chromosomes dividing the cell ParentParent cellcell 2 identical daughter cells2 identical daughter cells ChromosomeChromosome doublesdoubles Cell splitsCell splits
- 8. Prokaryotic Cell UndergoingProkaryotic Cell Undergoing Binary FissionBinary Fission
- 10. Five Phases of the CellFive Phases of the Cell CycleCycle GG11 - primary growth phase- primary growth phase S – synthesis; DNA replicatedS – synthesis; DNA replicated GG22 - secondary growth phase- secondary growth phase collectively these 3 stagescollectively these 3 stages are called interphaseare called interphase M - mitosisM - mitosis C - cytokinesisC - cytokinesis
- 12. 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
- 13. Interphase – S StageInterphase – S Stage SynthesisSynthesis stagestage DNADNA is copied oris copied or replicatedreplicated TwoTwo identicalidentical copiescopies of DNAof DNA OriginalOriginal DNADNA
- 14. 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
- 15. What’s Happening in Interphase?What’s Happening in Interphase? What the cell looks likeWhat the cell looks like Animal Cell What’s occurring
- 16. 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
- 17. MitosisMitosis
- 18. Mitosis: the process by which cells reproduce themselves, resulting in daughter cells that contain the same amount of genetic material as the parent cell. Division of theDivision of the nucleusnucleus Also calledAlso called karyokinesiskaryokinesis Only occurs inOnly occurs in eukaryoteseukaryotes HasHas fourfour stagesstages Doesn’t occur in some cells suchDoesn’t occur in some cells such asas brain cellsbrain cells
- 19. Four Mitotic StagesFour Mitotic Stages ProProphasephase MetaMetaphasephase AnaAnaphasephase TeloTelophasephase
- 20. ProphaseProphase 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 betweenfinishes forming between thethe poles of the cellpoles of the cell
- 21. 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 poleextend from one pole of the cell to the opposite poleof the 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
- 22. Sketch The SpindleSketch The Spindle
- 23. MetaphaseMetaphase Chromosomes, attached to theChromosomes, attached to the kinetochore fiberskinetochore fibers, move to the, move to the center of the cellcenter of the cell Chromosomes are now lined up atChromosomes are now lined up at the equatorthe equator Pole ofPole of the Cellthe Cell Equator of CellEquator of Cell
- 24. AnaphaseAnaphase OccursOccurs rapidlyrapidly SisterSister chromatidschromatids areare pulled apart topulled apart to opposite polesopposite poles of the cell byof the cell by kinetochorekinetochore fibersfibers
- 25. Anaphase ReviewAnaphase Review What theWhat the cell lookscell looks likelike What’sWhat’s occurringoccurring
- 26. 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
- 27. Comparison of Anaphase & TelophaseComparison of Anaphase & Telophase
- 28. 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
- 29. 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)
- 30. 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
- 31. Eukaryotic Cell DivisionEukaryotic Cell Division Used forUsed for growth and repairgrowth and repair Produce two new cellsProduce two new cells identical to the original cellidentical to the original cell Cells areCells are diploid (2n)diploid (2n) Chromosomes duringChromosomes during Metaphase of mitosisMetaphase of mitosis ProphaseProphase MetaphaseMetaphase AnaphaseAnaphase TelophaseTelophase CytokinesisCytokinesis
- 32. 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 increaseincrease the chance that athe chance that a normal cell developsnormal cell develops into ainto a tumor celltumor cell Cancer cellsCancer cells
- 33. MeiosisMeiosis Formation of GametesFormation of Gametes (Eggs & Sperm)(Eggs & Sperm)
- 34. 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)
- 35. 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))
- 36. 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
- 37. 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
- 38. Fertilization – “Putting it allFertilization – “Putting it all together”together” 1n =31n =3 2n = 62n = 6
- 39. Replication ofReplication of ChromosomesChromosomes 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
- 40. Meiosis: Two Part Cell DivisionMeiosis: Two Part Cell Division HomologsHomologs separateseparate SisterSister chromatidschromatids separateseparate DiploidDiploid MeiosisMeiosis II MeiosisMeiosis IIII DiploidDiploid HaploidHaploid
- 41. 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)
- 42. 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.
- 43. Tetrads Form in ProphaseTetrads Form in Prophase IIHomologous chromosomesHomologous chromosomes (each with sister chromatids)(each with sister chromatids) Join to form aJoin to form a TETRADTETRAD Called SynapsisCalled Synapsis
- 44. 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
- 45. Metaphase IMetaphase I Homologous pairsHomologous pairs of chromosomesof chromosomes align along thealign along the equatorequator of theof the cellcell
- 46. Anaphase IAnaphase I Homologs separateHomologs separate andand move to opposite poles.move to opposite poles. Sister chromatidsSister chromatids remainremain attachedattached at theirat their centromerescentromeres.
- 47. Telophase ITelophase I Nuclear envelopesNuclear envelopes reassemble.reassemble. Spindle disappears.Spindle disappears. CytokinesisCytokinesis divides celldivides cell into two.into two.
- 48. 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
- 49. Meiosis II: ReducingMeiosis II: Reducing Chromosome NumberChromosome Number ProphaseProphase IIII MetaphaseMetaphase IIII AnaphaseAnaphase IIII TelophaseTelophase IIII 4 Identical4 Identical haploid cellshaploid cells
- 50. Prophase IIProphase II Nuclear envelopeNuclear envelope fragments.fragments. Spindle forms.Spindle forms.
- 51. Metaphase IIMetaphase II Chromosomes alignChromosomes align alongalong equatorequator of cellof cell..
- 52. Anaphase IIAnaphase II Sister chromatidsSister chromatids separate andseparate and move tomove to oppositeopposite polespoles. EquatorEquator PolePole
- 53. Telophase IITelophase II Nuclear envelopeNuclear envelope assembles.assembles. ChromosomesChromosomes decondense.decondense. Spindle disappears.Spindle disappears. Cytokinesis dividesCytokinesis divides cell into two.cell into two.
- 54. 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
- 56. MitosisMitosis MeiosisMeiosis Number of divisionsNumber of divisions 11 22 Number of daughterNumber of daughter cellscells 22 44 Genetically identical?Genetically 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 and repairGrowth and repair Sexual reproductionSexual reproduction Comparison of DivisionsComparison of Divisions
Editor's Notes
- #40: 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.