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DO NOW ! Page 15

DO NOW ! Page 15. Meiosis. Agenda. Notebook Check (bin in the back). Mitosis Review…for some Candy…. What are the steps of mitosis? What is the purpose of mitosis? Is it asexual or sexual? Why?. Gamete : Sex Cell (sperm or egg) Diploid : Have pairs of chromosomes

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DO NOW ! Page 15

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  1. DO NOW! Page 15 Meiosis

  2. Agenda • Notebook Check (bin in the back)

  3. Mitosis Review…for some Candy… • What are the steps of mitosis? • What is the purpose of mitosis? • Is it asexual or sexual? Why?

  4. Gamete: Sex Cell (sperm or egg) • Diploid: Have pairs of chromosomes • Haploid: Have half the number of chromosomes • Zygote: Combination of Sex Cells after fertilization

  5. Diploid vs. Haploid http://www.youtube.com/watch?v=MU83VWAvUf4

  6. MEIOSIS is… • Meiosis is a form of cell division that produces SEX CELLS (gametes), such as sperm and egg. • Gametes are haploid; they have only half the number of chromosomes as a normal body cell. • Fertilization restores the chromosomes in body cells to the diploid number.

  7. Purpose of Meiosis • Produce haploid eggs and sperm (23 chromosomes in humans) • Meiosis consists of two cell divisions. • Meiosis I separates pairs of homologous chromosomes (46 chromosomes in each cell) • Meiosis II separates sister chromatids (23 chromosomes in each egg or sperm)

  8. Simplified… • MEIOSIS creates the variety we see among individuals (animals, plants, etc.) because it leads to the mixing of genetic information

  9. Phases of Mitosis • Two phases! • Remember PMAT? • Prophase, Metaphase, Anaphase, Telophase? • In Meiosis there is PMAT TWICE

  10. So is Meiosis Sexual or Asexual? For candy, tell me which one and why….

  11. Some things to look at: • http://www.cellsalive.com/meiosis.htm • http://www.youtube.com/watch?v=D1_-mQS_FZ0 • http://www.youtube.com/watch?v=iCL6d0OwKt8

  12. Mitosis vs. Meiosis • During prophase I: The chromosomes become visible and the centrioles begin forming spindle fibers • At this stage each chromosome is split into two sister chromatids. • The paired chromosomes now have four chromatids (2 sets of 'sisters') pressed together. • Crossing over takes place between two of the non-sister chromatids; the other two remain uncrossed. The crossover results in the exchange chromosomes.

  13. SO TO REMEMBER… • Mitosis— • Growth, Repair, and reproduction of simple cells • One cell to two identical offspring cell • Asexual • PMAT • Meiosis— • Reproduction process to create sperm and eggs • One cell to four different offspring cells with half the number of chromosomes • Sexual Reproduction process • PMATPMAT

  14. How do cells divide in meiosis?

  15. Exit Ticket Meiosis Mitosis

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