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Cell Division: Cells do not increase in size. They increase in number. PowerPoint Presentation
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Cell Division: Cells do not increase in size. They increase in number.

Cell Division: Cells do not increase in size. They increase in number.

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Cell Division: Cells do not increase in size. They increase in number.

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  1. Cell Division:Cells do not increase in size. They increase in number. Chapter 8-2 & 8-3

  2. Cell Cycle • Time from beginning of one cell division to the beginning of the next • Cell doubles its contents so it is ready to divide into two completely independent cells • 3 steps: • Interphase • Mitosis (M phase) • Cytokinesis

  3. G1 – cell grows in size, organelles in cytoplasm are copied S – DNA is copied G2 – cell prepares for division Cells spend most of their lifetime in interphase 1. Interphase (G1, S, & G2 phase)

  4. 2. Mitosis (M phase) • Division of the nucleus • Creates two identical diploid cells • PMAT

  5. Nuclear membrane disappears DNA – shorter and thicker and forms a chromosome Chromosomes double to sister chromatids Centrioles move to opposite ends of a cell Spindle fiber – cell skeleton begins to form Mitosis – Prophase

  6. Doubled chromosomes attach to spindle fibers by the centromeres Chromosomes pushed and pulled by spindle fibers Line up along the middle Shortest stage Mitosis - Metaphase

  7. Sister chromatids separate at the center Centromeres split apart Each sister chromatid is pulled toward an opposite side of the cell Mitosis - Anaphase

  8. Chromatids reach opposite poles Spindles break down Nuclear membrane reappears There are now 2 separate nuclei Mitosis - Telophase

  9. 3. Cytokinesis • Division of cytoplasm • Cell membrane pinches to form two new cells • Animal cells – cytoplasm & cell membrane pinches • Plant cells – cell plate forms and becomes the cell wall

  10. Cell Cycle – Animal Cell

  11. Cell Cycle – Plant Cell

  12. Whitefish

  13. Onion Root Tip

  14. Cells do not increase in size. They increase in number. • Meiosis: reduces the chromosome number by half in new cells (gametes)

  15. Meiosis • Creates four haploid cells (gametes) • Two nuclear divisions occur without DNA being copied in between

  16. Meiosis • Interphase • Meiosis I • Prophase I • Metaphase I • Anaphase I • Telophase I & Cytokinesis (results in 2 diploid cells) • Goes directly into Meiosis II • Prophase II • Metaphase II • Anaphase II • Telophase II & Cytokinesis (results in 4 haploid cells)