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Bellwork Wednesday January 28, 2015

Bellwork Wednesday January 28, 2015. 1) Give an example of how your body uses asexual reproduction. 2) List, in the correct order, the 6 phases of mitosis. 3) Which phases technically happens after the process of mitosis ends?. Meiosis. Cell division through sexual reproduction.

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Bellwork Wednesday January 28, 2015

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  1. BellworkWednesday January 28, 2015 • 1) Give an example of how your body uses asexual reproduction. • 2) List, in the correct order, the 6 phases of mitosis. • 3) Which phases technically happens after the process of mitosis ends?

  2. Meiosis Cell division through sexual reproduction

  3. Meiosis Definition • Cell division by which eggs and sperm are produced. • The production of sex cells, which are not genetically identical, through a series of cell divisions.

  4. Sexual Reproduction • the production of new living organisms by combining genetic information from two individuals of different types (sexes)

  5. Ensures that humans have the same number of chromosomes in each generation.

  6. It is a two-step process that reduces the chromosome number by half—from 46 to 23—to form sperm and egg cells. This is a reduction in genetic material.

  7. When the sperm and egg cells join at fertilization, each contributes 23 chromosomes so the resulting embryo will have the usual 46.

  8. Meiosis also allows genetic variation through a process of DNA shuffling while the cells are dividing.

  9. Meiosis • TWO divisions • ONE DNA replication

  10. Meiosis • Interphase: Before meiosis begins, genetic material is duplicated. • First division of meiosis • Prophase 1: Duplicated chromatin condenses. Each chromosome consists of two, closely associated sister chromatids. Crossing over can occur during the latter part of this stage. • Metaphase 1: Homologous chromosomes align at the equatorial plate. • Anaphase 1: Homologous pairs separate with sister chromatids remaining together. • Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the homologous pair.

  11. Meiosis • Second division of meiosis: Gamete (sex cell) formation • Prophase 2: DNA does not replicate. • Metaphase 2: Chromosomes align at the equatorial plate. • Anaphase 2: Centromeres divide and sister chromatids migrate separately to each pole. • Telophase 2: Cell division is complete. Four haploid daughter cells are obtained. • One parent cell producesfour daughter cells. Daughter cells have half the number of chromosomes found in the original parent cell and with crossing over, are genetically different.

  12. http://www.palaeos.com/

  13. Crossing Over • Where a section of one chromosome switches places with the same section from the other chromosome of the pair.

  14. http://www.accessexcellence.org

  15. http://post.queensu.ca/

  16. Animation http://www.johnkyrk.com/meiosis.html

  17. Animation http://www.csuchico.edu/~jbell/Biol207/animations/meiosis.html

  18. Meiosis Diagram On the back of your guided notes: Draw the diagram from pages 548-549 of your textbook depicting the stages of meiosis.

  19. Homework • Meiosis Reading Worksheet • Read the material and answer the multiple choice quesitons.

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