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Meiosis and Genetic Variation in Biology Class

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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