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Chapter 10: Cell Growth and Division Mitosis/Cancer

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Why is it necessary for cells to divide? DNA Overload-not enough information for the cell as it grows larger in size To improve material exchange Surface area to volume-not enough cell membrane surface for exchange thats required of larger volume cell as it grows

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Cell Size Surface Area (length x width x 6) Volume (length x width x height) Ratio of Surface Area to Volume Ratio of Surface Area to Volume in Cells Section 10-1

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What is Cell Division (M phase)? process where a cell divides into two new daughter cells Before cell division takes place, the cell must copy or replicate its DNA. Each daughter cells gets a complete copy of the original DNA Cell division has 2 parts Mitosis: division of nucleus and DNA Cytokinesis: division of cytoplasm and organelles

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Mitosis (1 st stage of cell division) 4 parts of mitosis Prophase Metaphase Anaphase Telophase Mitosis is followed by 2 nd part of cell division; cytokinesis

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Interphase Prophase Anaphase Telophase/Cytokinesis

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Cell Growth- protein and organelle production DNA Replication Preparation for division- organelle replication

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M phase G 2 phase S phase G 1 phase Figure 104 The Cell Cycle

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Interphase G1 phase: Cell Growth S phase: DNA replication G2 phase: Preparation for Mitosis Longest phase of cell cycle

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Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Figure 105 Mitosis and Cytokinesis

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Prophase- Phase #1 of Mitosis Longest Phase-50% to 60% of total time to complete mitosis Chromatin condenses into Chromosomes Centromeres connect sister chromatids Centrioles separate to opposite poles Spindle is organized Nucleolus disappears and nuclear envelope breaks down.

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Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Figure 105 Mitosis and Cytokinesis

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Metaphase- Phase #2 of Mitosis Centromeres attach to spindle fibers Chromosomes line up across the equator of the cell-metaphase plate

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Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Figure 105 Mitosis and Cytokinesis

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Anaphase- Phase #3 of Mitosis Sister chromatids separate becoming individual chromosomes and moving to opposite poles of cell

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Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Figure 105 Mitosis and Cytokinesis

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Telophase- Phase #4 of Mitosis Chromosomes disperse into chromatin Nuclear envelope re-forms around each cluster of chromatin Spindle breaks apart Nucleolus visible in each new daughter cell (2 new nuclei form)

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Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Figure 105 Mitosis and Cytokinesis

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Cytokinesis Division of cytoplasm and organelles Animal Cells: Cleavage Furrow-cell membrane pinches inward Plant Cells: Cell Plate-develops into separating membrane (cell wall appears shortly after) 2 new daughter cells each with nucleus and identical chromosomes

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Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Figure 105 Mitosis and Cytokinesis

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Cytokinesis

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Longest Phase-50% to 60% of total time to complete mitosis-Prophase

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Prophase Interphase

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Metaphase Prophase

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Anaphase

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Telophase

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Cyclins: proteins that regulate timing of cell cycle Two types of regulatory proteins Internal regulators: proteins that respond to events inside the cell (ex. No mitosis until all chromosomes are replicated) External regulators: Proteins that respond to events outside cell Speed up, or slow down cell cycle Ex: wound healing and embryonic development

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A sample of cytoplasm is removed from a cell in mitosis. The sample is injected into a second cell in G 2 of interphase. As a result, the second cell enters mitosis. Figure 108 Effect of Cyclins -

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Cancer: Disorder in which some cells lose ability to control growth Density-Dependent Inhibition- ability to respond to signals that regulate the growth of cells Cancer cells do not exhibit this characteristic form tumors Carcinogen- cancer causing agent (ex. Cigarettes, UV radiation from sun)

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Cancer Divide uncontrollably and form tumors Damage surrounding tissues P53 Gene: stops cell cycle until replication is complete defect in this gene present in a large number of cancers

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Tumors Masses of cells that can damage surrounding tissue Benign-non-cancerous growth Localized and not spread Malignant-cancerous growth Invade and damage nearby tissues and organs Metastasis-spread of cancer

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Regulating the Cell Cycle

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Why didnt the cells keep dividing until they spilled over the edge of the petri dish? What would happen if the cells continued to divide?

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Skin Cancer : Melanoma Asymmetrical, Borders, Color, Diameter, Elevation