Sci 9A Lesson 2 Mar 16 - Introduction to Genetics (Part 2)

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  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Mendelian Genetics 04/03/11
  • Sci 9A Lesson 2 Mar 16 - Introduction to Genetics (Part 2)

    1. 1. HOMEWORK FROM LAST CLASS: <ul><li>Complete the Genetics Practice Problems worksheet (1 st side) </li></ul><ul><li>Read over class notes and check out the class blog: http://msoonscience.blogspot.com/ </li></ul>
    2. 2. INTRODUCTION TO GENETICS - REVIEW
    3. 3. <ul><li>Remember me? Who am I? </li></ul><ul><li>I’m Gregor Mendel, the “Father of Genetics”! </li></ul><ul><li>I’m an Austrian monk who studied the inheritance of traits (characteristics) in pea plants. </li></ul>Pea 
    4. 4. GREGOR MENDEL RAP <ul><li>http://www.youtube.com/watch?v=EvR_Sdm1orU </li></ul>
    5. 5. Definitions: trait: a characteristic that can be passed from parent to offspring heredity: the passing of traits from parents to offspring genetics: the study of heredity
    6. 6. Allele: a form of a gene Dominant: allele that is expressed (regardless of its counterpart allele); represented by a capital letter (e.g. T) Recessive: allele that is expressed only when its counterpart allele is also recessive ; represented by a small letter (e.g. t) Examples of traits in pea plants
    7. 7. GENOTYPE AND PHENOTYPE Genotype: the combination of alleles for a trait e.g. TT, Tt, tt Phenotype: the physical feature resulting from a genotype e.g. tall, short
    8. 8. GENOTYPES <ul><li>Homozygous genotype (aka pure): </li></ul><ul><li>2 dominant or 2 recessive genes </li></ul><ul><li>(e.g. TT or tt) </li></ul><ul><li>Heterozygous genotype (aka hybrid): </li></ul><ul><li>1 dominant and 1 recessive allele </li></ul><ul><li>(e.g. Tt) </li></ul><ul><li>T > t </li></ul><ul><li>= Dominant allele is expressed over the recessive allele </li></ul>
    9. 9. Practice time! Fill in the chart on the next page with the correct genotype and phenotype for the pea plant traits. TRAIT DOMINANT RECESSIVE P A Y R p a y r
    10. 10. Trait Genotype Phenotype Flour colour White AA Seed colour yy Round
    11. 11. SOLUTION Trait Genotype Phenotype Flour colour pp White Flower position AA Axial Seed colour yy Green Seed shape RR or Rr Round
    12. 12. PUNNETT SQUARE <ul><li>Shows what the offspring of a female and male parent will look like </li></ul>An example of a Punnett square
    13. 13. GENERATION “GAP” Parent generation (P1) 1 st filial generation (F1) 2 nd filial generation (F2)
    14. 14. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). R r r r
    15. 15. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). What percentage of the offspring will be round? 50% R r r r Rr rr Rr rr
    16. 16. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). R r R r
    17. 17. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). What percentage of the offspring will be round? 75% R r R r RR Rr Rr rr
    18. 18. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). R R R r
    19. 19. 4. Set up the Punnett square for each of the crosses below. The trait being studied is round seeds (dominant = R) and wrinkled seeds (recessive = r). What percentage of the offspring will be round? 100% R R R r RR RR Rr Rr
    20. 20. INCOMPLETE DOMINANCE <ul><li>Genes are not always dominant or recessive —in some gene pairs, the genes are neither dominant nor recessive. </li></ul><ul><ul><li>Instead, these genes show incomplete dominance </li></ul></ul><ul><ul><li>Incomplete dominance: </li></ul></ul><ul><ul><li>neither gene in a gene pair masks the other </li></ul></ul><ul><ul><li> The traits carried by the 2 genes are blended </li></ul></ul>
    21. 21. INCOMPLETE DOMINANCE Neither the red gene (R) nor the white gene (W) is dominant. When the 2 genes are present in the same plant, a pink flower results. Both R and W are used (capital letters) because neither the red gene nor the white gene is dominant over the other. White Red
    22. 22. GREGOR MENDEL’S PUNNETT SQUARES <ul><li>http://www.youtube.com/watch?v=d4izVAkhMPQ&feature=player_embedded </li></ul>
    23. 23. ACTIVITY! <ul><li>Paint your paper maché eggs and sperm! </li></ul>
    24. 24. INSTRUCTIONS <ul><li>1) Find your pair’s egg or sperm. </li></ul><ul><li>2) Put newspaper down on your lab bench. </li></ul><ul><li>3) Paint your egg or sperm— get creative! </li></ul><ul><li>4) Place your painted egg or sperm on top of newspaper under the counter to dry. </li></ul><ul><li>I will hang the eggs and sperm in the classroom when they are dry! </li></ul>
    25. 25. HOMEWORK FOR NEXT CLASS: <ul><li>Finish the back side of the Genetics Practice Problems worksheet </li></ul><ul><li>Read over class notes and check out the class blog: http://msoonscience.blogspot.com/ </li></ul>
    26. 26. WORKS CITED <ul><li>Images taken from the following sources: </li></ul><ul><li>http://bioserv.fiu.edu/~walterm/human_online/inheritance/introduction_to_genetics.htm </li></ul><ul><li>http://wps.prenhall.com/esm_freeman_biosci_1/0,6452,498846-,00.html </li></ul><ul><li>http://www.fotosearch.com/illustration/paint-bucket.html </li></ul><ul><li>PowerPoint source: http://www.biologyjunction.com/pwpt_biology.htm </li></ul><ul><li>Copyright C. Messengale </li></ul>

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