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Mitosis and Meiosis

Mitosis and Meiosis. Basic Cell Biology Topic 3202C, 3025G, 3025H Melinda Klockziem. Mitosis. How do cells reproduce?. Mitosis -- the cells divide to produce two identical cells. Genetic material in both is identical End up with two diploid cells

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Mitosis and Meiosis

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  1. Mitosis and Meiosis Basic Cell Biology Topic 3202C, 3025G, 3025H Melinda Klockziem

  2. Mitosis

  3. How do cells reproduce? • Mitosis -- the cells divide to produce two identical cells. • Genetic material in both is identical • End up with two diploid cells • Mitosis is necessary for growth and maintenance.

  4. Stages of mitosis • 1. Interphase • The cell doubles its DNA • Nucleoli and nuclear membrane present http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  5. http://www.bioweb.uncc.edu/biol1110/Stages.htm

  6. Stages of mitosis • 2. Prophase • Sister Chromatids shorten and thicken • Chromosomes visible • Nuclear membrane disappears • Chromosomes have “X” shape joined at the centromere http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  7. http://www.bioweb.uncc.edu/biol1110/Stages.htm

  8. Stages of mitosis • 3. Metaphase • Sister chromatidsline up along equator of the cell • Attach to spindle fibers which act a guide to separate the sister chromatids http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  9. http://www.bioweb.uncc.edu/biol1110/Stages.htm

  10. Stages of mitosis • 4. Anaphase • Sister chromatids separate • Sister chromatids move to opposite ends of the cell http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  11. http://www.bioweb.uncc.edu/biol1110/Stages.htm

  12. Stages of mitosis • 5. Telophase • Nuclear membranes reform • Two new cells are separated • Cytokinesis occurs http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  13. http://www.bioweb.uncc.edu/biol1110/Stages.htm

  14. Animation of Mitosis Cell Alive Website

  15. Cancer and Mitosis • Mitosis is necessary, but… • Uncontrolled mitosis is cancer. • Cancer cells divide without control. • Cancer cells create a mass in tissues or organs. • Two types of Cancer • Benign • Malignant

  16. Mitosis Yarn Lab

  17. Meiosis

  18. Background Information • Chromosome Numbers • Haploid or N • Humans 23 Haploid number (N) • Chromosomes are in pairs • Humans have a total of 46 chromosomes or 2N (diploid) • Meiosis reduces 2N to N • Thus when sperm and ova meet and combine at fertilization the resulting embryo will have 2N

  19. How else do cells reproduce? • Meiosis is the reproduction of animal sex cells • Ova and sperm • Happens in two stages • Two divisions of the cell compared to only one division in mitosis • End up with four haploid cells

  20. Stages of Meiosis I • Prophase I • Chromosomes thicken and becomes visible • Chromosomes are present in homologous pairs http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  21. Stages of Meiosis I • Metaphase I • Homologous pairs line up on the axis of the dividing cell opposite from each other. http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  22. Stages of Meiosis I • Anaphase I • Homologous pairs of chromosomes leave each other and are pulled towards opposite poles by spindle fibers http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  23. Stages of Meiosis I • Telophase I • The cells physically divide • Each daughter cell now contains one chromosome from each pair • Reduction Division • Number of chromosomes is reduced from diploid tohaploid. http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  24. Stages of Meiosis II • Prophase II • Chromosomes still duplicated http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  25. Stages of Meiosis II • Metaphase II • Sister chromatids line up on the axis of the cell. http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  26. Stages of Meiosis II • Anaphase II • The sister chromatids are pulled apart at the centromere by spindle fiber http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

  27. Stages of Meiosis II • Telophase II • Nuclear membrane reforms • Each of the four final haploid cells or gametes contain one strand from the original homologous pair of chromosomes. http://www.erin.utoronto.ca/~w3bio380/Lectsked/Supple2/meiosis.html

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