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Cell Cycle

Cell Cycle. Life of a Eukaryotic Cell. Cell Cycle. (Interphase in Red) G1 – cell grows & carries out major functions S – DNA is copied G2 – Prep for mitosis; organelles reproduced Mitosis – Nucleus divided into two nuclei, each with same number and kind of chromosomes

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Cell Cycle

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  1. Cell Cycle Life of a Eukaryotic Cell

  2. Cell Cycle

  3. (Interphase in Red) • G1 – cell grows & carries out major functions • S – DNA is copied • G2 – Prep for mitosis; organelles reproduced • Mitosis – Nucleus divided into two nuclei, each with same number and kind of chromosomes • Cytokinesis – cytoplasm divides

  4. Cell Cycle Control • How does cell “know” when to divide? • Cell cycle controlled by many proteins (enzymes) at three main checkpoints: • G1 checkpoint – decision made whether cell will divide (cell healthy and large enough). Some types of cell never pass this point (nerve, muscle) • G2 checkpoint – Did DNA replication go OK? If so, go on to mitosis • Mitosis checkpoint – Is mitosis over? If so, head to G1 phase

  5. Cancer - What happens if control is lost • Cancer = uncontrolled cell growth • Disorder of cell division • Control mechanisms don’t work (gene for proteins that control cell cycle are defective) • Mutations: • Overproduction of growth-promoting hormones – speeds up cell cycle • Inactivation the control proteins that act to slow or stop cell cycle

  6. Mitosis and Cytokinesis • Chromatids are physically moved to opposite sides of dividing cells with help of spindle fibers • Centrosome (in animals) – made up of two centrioles - organizes assembly of spindle fibers • Spindle fibers made from microtubules

  7. Mitosis and Cytokinesis • Chromatids separate by attaching spindle fibers • Spindle fibers attach to centromeres of chromosomes • Paired chromatids separate. One chromatid goes to one pole of the cell, the other chromatid goes to the other as the spindle fibers shorten

  8. Interphase (90% of cell’s time)Mitosis (nuclear division)ProphaseMetaphaseAnaphaseTelophaseCytokinesis (cytoplasmic division) Watch video clip of mitosis

  9. Another View of Mitosis

  10. Mitosis Foldable • 6 sheets of paper • Follow teacher’s instructions to construct booklet • You will make foldable based on pictures and descriptions of interphase, cyokinesis, and mitosis in your book (p. 125 and pp 130 – 132) • Include sketches and textual descriptions in foldable • You can also use www.cellsalive.com and www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/main.html

  11. Headings for foldable • Cover = Phases of Somatic Cell Division • Following sheets – • Interphase • G1 • S • G2 • Mitosis • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis

  12. Homework • Read Ch. 7 – “Meiosis and Sexual Reproduction” • Also read about plant reproduction pp. 534 – 535, and pp. 538 – 539 • Complete Guided Reading packet for Chapter 7 • Complete Foldable

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