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Cell Division and Mitosis Chapter 10
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10.1 The Cycle of Cell Growth and Division: An Overview The products of mitosis are genetic duplicates of the dividing cell Chromosomes are the genetic units divided by mitosis
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Mitotic Cell Division DNA replication Equal separation (segregation) of replicated DNA molecules Delivery to daughter cells Two new cells, same information as parent cell
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Mitosis Mitosis is the basis for Growth and maintenance of body mass in multicelled eukaryotes Reproduction of many single-celled eukaryotes
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Chromosomes DNA of eukaryotic cells is divided among individual, linear chromosomes Located in cell nucleus Ploidy of a cell or species Diploid (2n) Haploid (n)
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Eukaryotic Chromosomes Fig. 10-2, p. 203
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Sister Chromatids DNA replication and duplication of chromosomal proteins produces two exact copies (sister chromatids) Chromosome segregation occurs during cell division
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10.2 The Mitotic Cell Cycle Interphase extends from the end of one mitosis to the beginning of the next mitosis After interphase, mitosis proceeds in five stages Cytokinesis completes cell division by dividing the cytoplasm between daughter cells
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10.2 (cont.) The mitotic cell cycle is significant for both development and reproduction Mitosis varies in detail, but always produces duplicate nuclei
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Mitotic Cell Cycle Includes mitosis and interphase Mitosis occurs in five stages Prophase Prometaphase Metaphase Anaphase Telophase
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The Cell Cycle Fig. 10-3, p. 203
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Interphase Fig. 10-4a (1), p. 204
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Fig. 10-4b, p. 205
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Stage 1: Prophase Chromosomes condense into short rods Spindle forms in the cytoplasm
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Prophase Fig. 10-4a (2), p. 204
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Stage 2: Prometaphase Nuclear envelope breaks down Spindle enters former nuclear area Sister chromatids of each chromosome connect to opposite spindle poles Kinetochore of each chromatid attaches to the spindle microtubules
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Prometaphase Fig. 10-4a, p. 204
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Spindle Connections at Prometaphase Fig. 10-6, p. 206
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Stage 3: Metaphase Spindle is fully formed Chromosomes align at metaphase plate Moved by spindle microtubules
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Metaphase Fig. 10-4b, p. 204
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Stage 4: Anaphase Spindle separates sister chromatids and moves them to opposite spindle poles Chromosome segregation is complete
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Anaphase Fig. 10-4b, p. 204
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Stage 5: Telophase Chromosomes decondense Return to extended state typical of interphase New nuclear envelope forms around chromosomes
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Telophase Fig. 10-4b, p. 204
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Animation: Mitosis step-by-step
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Mitosis Fig. 10-5, p. 206
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Cytokinesis Division of cytoplasm completes cell division Produces two daughter cells Each daughter nucleus produced by mitosis
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Cytokinesis in Animal Cells Proceeds by furrowing Band of microfilaments just under the plasma membrane contracts Gradually separates cytoplasm into two parts
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Cytokinesis by Furrowing Fig. 10-8, p. 208
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Plant Cytokinesis Cell wall material is deposited along the plane of the former spindle midpoint Deposition continues until a continuous new wall (cell plate) separates daughter cells
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Cytokinesis by Cell Plate Formation Fig. 10-9, p. 208
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10.3 Formation and Action of the Mitotic Spindle Animals and plants form spindles in different ways Mitotic spindles move chromosomes by a combination of two mechanisms
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Spindle Formation In animal cells Centrosome divides, the two parts move apart Microtubules of the spindle form between them In plant cells with no centrosome Spindle microtubules assemble around the nucleus
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Centrosome and Spindle Formation Fig. 10-10, p. 210
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In the Spindle Kinetochore microtubules Run from poles to kinetochores of chromosomes Nonkinetochore microtubules Run from poles to a zone of overlap at the spindle midpoint without connecting to chromosomes
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A Fully Developed Spindle Fig. 10-11, p. 210
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During Anaphase Kinetochores move along kinetochore microtubules Pulling chromosomes to the poles Nonkinetochore microtubules slide over each other Pushing the poles farther apart
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Anaphase Spindle Movements Fig. 10-12, p. 211
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Kinetochore Movement Fig. 10-13, p. 211
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10.4 Cell Cycle Regulation Cyclins and cyclin-dependent kinases Internal controls that directly regulate cell division Internal checkpoints Stop cell cycle if stages are incomplete External controls Coordinate mitotic cell cycle of individual cells within overall activities of the organism
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Cell Cycle Control (1) Complexes of cyclin and a cyclin-dependent protein kinase (CDK) Directly control cell cycle CDK Is activated when combined with a cyclin Adds phosphate groups to target proteins, activating them
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Cell Cycle Control (2) Activated proteins trigger the cell to progress to the next cell cycle stage Each major stage of the cell cycle Begins with activation of one or more cyclin/CDK complexes Ends with deactivation of complexes by breakdown of cyclins
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Cyclin/CDK Control Fig. 10-15, p. 214
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Internal Controls Important internal controls create checkpoints Ensure that the reactions of one stage are complete before cycle proceeds to next stage
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External Controls Based on surface receptors that recognize and bind signals Peptide hormones and growth factors Surface groups on other cells Molecules of the extracellular matrix Binding triggers internal reactions that speed, slow, or stop cell division
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Cancer Control of cell division is lost Cells divide continuously and uncontrollably Form rapidly growing mass of cells that interferes with body functions Cancer cells break loose from their original tumor (metastasize) Form additional tumors in other parts of the body
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Tumor Cells Fig. 10-16, p. 215
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Animation: Mitosis overview PLAY ANIMATION
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