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

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Presentation on theme: "Mitosis and Meiosis Basic Cell Biology Topic 3202C, 3025G, 3025H Melinda Klockziem."— Presentation transcript:

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 meiosis.html

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6 Stages of mitosis 2. Prophase – Sister Chromatids shorten and thicken – Chromosomes visible – Nuclear membrane disappears – Chromosomes have “X” shape joined at the centromere

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8 Stages of mitosis 3. Metaphase – Sister chromatids line up along equator of the cell – Attach to spindle fibers which act a guide to separate the sister chromatids l

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10 Stages of mitosis 4. Anaphase – Sister chromatids separate – Sister chromatids move to opposite ends of the cell

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12 Stages of mitosis 5. Telophase – Nuclear membranes reform – Two new cells are separated – Cytokinesis occurs

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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 meiosis.html

21 Stages of Meiosis I Metaphase I – Homologous pairs line up on the axis of the dividing cell opposite from each other. 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

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 to haploid. meiosis.html

24 Stages of Meiosis II Prophase II – Chromosomes still duplicated meiosis.html

25 Stages of Meiosis II Metaphase II – Sister chromatids line up on the axis of the cell. meiosis.html

26 Stages of Meiosis II Anaphase II – The sister chromatids are pulled apart at the centromere by spindle fiber 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.


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