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Genetics

Genetics. I. Mendelian. A. Introduction. 1. History. a. C . Darwin & A . Wallace == blending. b. In 1860, G . Mendel & F . Unger == mixing. B. Experimental Design. 1. Monohybrid Cross. a. Definition. b. Terms. i. Self vs. Cross Fertilization.

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Genetics

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  1. Genetics I. Mendelian A.Introduction 1. History

  2. a. C. Darwin & A. Wallace == blending

  3. b. In 1860, G. Mendel & F. Unger == mixing

  4. B.Experimental Design 1. Monohybrid Cross a. Definition

  5. b. Terms i. Self vs. Cross Fertilization ii. Traits vs. Characteristics

  6. c. Process

  7. Figure 10.1 Figure 10.2

  8. i. Outcomes for a one trait cross or Monohybrid crosses ii. Principle All traits are paired and sorted into gametes Figure 10.3

  9. d. Terms

  10. Gene versus Allele Homozygous versus Heterozygous Dominance versus Recessive Genotype versus Phenotype

  11. e. Testcross

  12. Figure 10.4

  13. 2. Dihybrid Cross a. Definition b. Process

  14. i. Outcomes for a Dihybrid crosses Always start these crossing questions by figuring out how many andwhat type of gametes are produced by the parents. Figure 10.6

  15. i. Outcomes Dihybrid Heterozygous cross = AaBb X AaBb Gametes AaBb = AB, Ab, aB, & ab for both Phenotypic ratio= 9:3:3:1, Genotypic ratio= 1:1:2:2:4:2:2:1:1 Dihybrid Heterozygous cross Homozygous Dominant = AaBb X AABB Gametes AaBb = AB, Ab, aB, & ab; AABB= AB only Phenotypic ratio = all dominant, Genotypic ratio = 1:1:1:1 ii. Principle Each pair of alleles and chromosomes sort independently into gametes.

  16. II. Variation on Mendel A.Incomplete Dominance

  17. Incomplete dominanceappears to be a blending of the two alleles vs. complete dominant. Figure 10.9

  18. B.Co-Dominance

  19. Co-dominance expression of alleles yields both traits in heterozygote. AA aa Aa

  20. C.Multiple Alleles

  21. Multiple alleles are needed to give the expression of the trait. Figure 10.10

  22. D.Penetrance

  23. Timing of expression of traits in the phenotype.

  24. E.Gene Interactions 1. Pleitrophy

  25. Pleitrophyone gene = many different effects Figure 10.13

  26. 2. Polygenic

  27. Polygenic = Continuous Variation of Expression of traits Figure 10.11

  28. 3. Epistasis

  29. Epistasis = Interference of expression between different genes

  30. III. Classical Genetics A.History

  31. 1. W. Bateson& R. Punnett (1908) PunnettSquare

  32. 2. T. Morgan (early 1900’s) used fruit flies WHY? Recombination experiments

  33. Developed karyotyping techniques, Figure 9.1

  34. linkage group studies, Figure 10.17 Figure 10.16

  35. & sex linkage studies Figure 10.15

  36. 3. A. Sturtevant a. mapping

  37. V. Detection of Problems

  38. A. Karyotyping B. Amniocentesis == Cellular and Chemical Analysis

  39. C. Ultrasound gives a visual image of the fetus D. Chorionic Villi Sampling== placenta samples

  40. E. Fetal Tissue

  41. F. Pedigrees == familial history Figure 13.7 Figure 13.8

  42. Figure 13.9

  43. Maximize your gifts.

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