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Lecture #5Lecture #5 Date ______ Date ______

a Chapter 12~Chapter 12~The Cell Cycle The Cell Cycle

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Cell Division: Key RolesCell Division: Key Rolesa Genome: cells genetic informationGenome: cells genetic informationa Somatic (body cells) cellsSomatic (body cells) cellsa Gametes (reproductive cells): sperm andGametes (reproductive cells): sperm and

egg cellsegg cellsa Chromosomes: DNA moleculesChromosomes: DNA moleculesa Diploid (2n): 2 sets of chromosomesDiploid (2n): 2 sets of chromosomesa Haploid (1n): 1 set of chromosomesHaploid (1n): 1 set of chromosomesa Chromatin: DNA-protein complex Chromatin: DNA-protein complex a Chromatids: replicated strands of aChromatids: replicated strands of a

chromosomechromosomea Centromere: narrowing waist of sisterCentromere: narrowing waist of sister

chromatidschromatidsa Mitosis: nuclear divisionMitosis: nuclear divisiona Cytokinesis: cytoplasm divisionCytokinesis: cytoplasm divisiona Meiosis: gamete cell divisionMeiosis: gamete cell division

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The Cell CycleThe Cell Cycle

a InterphaseInterphase (90% of cycle)(90% of cycle) G1 phase~ growth G1 phase~ growth S phase~ synthesis of DNA S phase~ synthesis of DNA G2 phase~ preparation for G2 phase~ preparation for

cell divisioncell divisiona Mitotic phaseMitotic phase

Mitosis~ nuclear division Mitosis~ nuclear division Cytokinesis~ cytoplasm Cytokinesis~ cytoplasm

divisiondivision

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MitosisMitosis

a ProphaseProphasea PrometaphasePrometaphasea MetaphaseMetaphasea Anaphase Anaphasea TelophaseTelophase

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MitosisMitosis

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ProphaseProphase

a Chromosomes visibleChromosomes visiblea Nucleoli disappearNucleoli disappeara Sister chromatidsSister chromatidsa Mitotic spindle formsMitotic spindle formsa Centrosomes moveCentrosomes move

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PrometaphasePrometaphase

a Nuclear membraneNuclear membranefragmentsfragments

a Spindle interactionSpindle interaction with chromosomes with chromosomes

a Kinetochore developsKinetochore developsQuickTime and a

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MetaphaseMetaphase

a Centrosomes atCentrosomes atopposite polesopposite poles

a Centromeres areCentromeres arealignedaligned

a Kinetochores of sisterKinetochores of sisterchromatids attachedchromatids attachedto microtubulesto microtubules(spindle)(spindle)

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Anaphase Anaphase

a Paired centromeresPaired centromeresseparate; sisterseparate; sister

chromatids liberatedchromatids liberateda Chromosomes moveChromosomes move

to opposite polesto opposite polesa Each pole now has aEach pole now has a

complete set ofcomplete set ofchromosomeschromosomes

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TelophaseTelophase

a Daughter nuclei formDaughter nuclei forma Nuclear envelopesNuclear envelopes

arisearisea Chromatin becomesChromatin becomes

less coiledless coileda

Two new nucleiTwo new nucleicomplete mitosiscomplete mitosis

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CytokinesisCytokinesis

a Cytoplasmic divisionCytoplasmic divisiona Animals: Animals:

cleavage furrowcleavage furrowa

Plants:Plants:cell platecell plate

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Cell Cycle regulationCell Cycle regulation

a

Growth factorsGrowth factorsa Density-dependentDensity-dependent

inhibitioninhibitiona Anchorage Anchorage

dependencedependence

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CancerCancer

a TransformationTransformationa Tumor: benign or malignantTumor: benign or malignanta MetastasisMetastasis