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Meiosis and Genetic Variation in Biology Class

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This class focuses on reviewing meiosis and learning about genetic variation. Topics include meiosis coloring, gametogenesis, and the importance of genetic variation in evolution.

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Meiosis and Genetic Variation in Biology Class

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  1. Hand in the W.S. 7.1 before the bell rings Review Chapter 6 Quiz 2 Continue Chapter 7 Meiosis coloring Gametogenesis Preview Genetic variation “I would rather fail in a cause that someday will triumph, than to win in a cause that I know will someday fail.” Woodrow Wilson To review learning about meiosis and learn about genetic variation due to meiosis Title: Biology 1/16/07 Class Topics Objectives: Thursday, January 2, 202011:52 AM

  2. Class Assignments What By When • Read 144-149 1/16/07 • W.S. 7.1 (DR/Quiz) 1/16/07 • Meiosis Coloring 1/16/07 • Chapter 7 Quiz 1 1/18/07 • W.S. Science Skills 1/18/07 • 2A only – p. 157 #16 & # 18 (paragraph) 1/17/07 • Due this class period • Due next class period • Due in the future

  3. Grade Sheet

  4. Meiosis: Totals • Four cells • All Haploid • Gametogenesis • Males - all usually develop completely • Spermatogenesis – forms sperm • Females - usually only 1 develops • Oogenesis – forms ova

  5. From: http://www.accessexcellence.org/AB/GG/meiosis.html

  6. Meiosis coloring • Choose four colors, one for each pair of homologous chromosomes • Draw in the chromosomes for all of the stages of meiosis using 8 chromosomes

  7. Chapter 7 Quiz 1 • Matching • Autosome, crossing over (trading genetic material), diploid, homologous, haploid, meiosis, synapsis, tetrad • Short answer • mitosis, meiosis, gametes, autosomes, spermatogenesis, oogenesis • Matching - meiosis • from the handout (6)

  8. Genetic variation • Allows for new genetic combinations • Unlike mitosis • 1. Independent assortment • Random distribution of homologous chromosomes • Each of the 23 pairs segregates independently • 223 combinations (8,388,608) from one cell

  9. Genetic variation (cont.) • 2. Crossing-over • Occurs during Prophase I when homologous chromosomes synapse • Trading of genetic material between homologous chromosomes (switching genes) • Increases genetic diversity

  10. Genetic variation (cont.) • 3. Random fertilization • Random fertilization means each gamete was independently assorted • (223 * 223) = 70,368,744,177,664 combinations

  11. Importance of genetic variation • Very important for evolution • change in characteristics of a population from one generation to the next • The pace of evolution can be sped up by increased genetic variation • Depends on natural selection

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