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

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Presentation on theme: "Genetics I. I. Mendelian 1. History A. Introduction."— Presentation transcript:

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

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

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

4 1. Monohybrid Cross B. Experimental Design 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 Always start these crossing questions by figuring out how many and what type of gametes are produced by the parents. i. Outcomes for a Dihybrid crosses Figure 10.6

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

16 II. II. Variation on Mendel A. Incomplete Dominance

17 Incomplete dominance appears 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 1. Pleitrophy E. Gene Interactions

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. III. Classical Genetics A. History

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

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

33 Developed karyotyping techniques, Figure 9.1

34 Figure 10.17 linkage group studies, Figure 10.16

35 & sex linkage studies Figure 10.15

36 3. A. A. Sturtevanta. mapping

37 V. 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 13.7Figure 13.8

42 Figure 13.9

43 Maximize your gifts.

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