682021 Title Biology 11607 Objectives To review learning

6/8/2021 Title: Biology 1/16/07 Objectives: To review learning about meiosis and learn about genetic variation due to meiosis Class Topics • 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 Tuesday, June 8, 2021 3: 37 AM 1

6/8/2021 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 2 A only – p. 157 #16 & # 18 (paragraph) 1/17/07 • Due this class period • Due next class period • Due in the future 2

6/8/2021 Grade Sheet 3

6/8/2021 Meiosis: Totals • Four cells • All Haploid • Gametogenesis – Males - all usually develop completely • Spermatogenesis – forms sperm – Females - usually only 1 develops • Oogenesis – forms ova 4

6/8/2021 From: http: //www. accessexcellence. org/AB/GG/meiosis. html 5

6/8/2021 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 6

6/8/2021 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) 7

6/8/2021 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 8

6/8/2021 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 9

6/8/2021 Genetic variation (cont. ) • 3. Random fertilization – Random fertilization means each gamete was independently assorted • (223 * 223) = 70, 368, 744, 177, 664 combinations 10

6/8/2021 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 11