Genetics

I. Mendelian A. Introduction 1. History a. C. Darwin & A. Wallace proposed blending b. In 1860, G. Mendel & F. Unger proposed mixing

B. Experimental Design 1. Monohybrid Cross a. Definition b. Terms i. Self vs. Cross Fertilization ii. Traits vs. Characteristics

c. Process Figure 10.1 Figure 10.2

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

ii. Homozygous versus Heterozygous d. Terms i. Gene versus Allele ii. Homozygous versus Heterozygous iii. Dominance versus Recessive iv. Genotype versus Phenotype e. Testcross What are the parental genotypes? Figure 10.4

2. Dihybrid Cross a. Definition b. Process Always start these crossing questions by figuring out the parents and then how many and what type of gametes are produced. Figure 10.6

i. Outcomes AaBb X AaBb Dihybrid Heterozygous cross Both Parents are AaBb Gametes = AB, Ab, aB, & ab for both parents Phenotypic ratio= 9:3:3:1 & Genotypic ratio= 1:1:2:2:4:2:2:1:1 Dihybrid Heterozygous cross with a Homozygous Dominant Parents are 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.

II. Variation on Mendel A. Incomplete Dominance Appears to be a blending of the two alleles vs. complete dominant. Figure 10.6

B. Co-Dominance AA aa Aa Expression of alleles yields both traits in heterozygote.

C. Multiple Alleles Figure 10.17 Multiple alleles are needed to give the expression of the trait.

D. Penetrance The timing of expression of traits in the phenotype.

E. Gene Interactions 1. Pleitrophy 2. Polygenic Figure 10.18 Figure 10.21 One gene causing many different effects Continuous Variation of Expression of traits

3. Epistasis Interference of expression between different genes Just to make sure you can tell the difference.

III. Classical Genetics A. History 1. W. Bateson & R. Punnett (1908) Punnett Square

2. T. Morgan (early 1900’s) used fruit flies WHY? Recombination experiments a. Developed karyotyping techniques, Figure 13.7

b. Discovered linkage group studies, Figure 9.4

& c. sex linkage studies. Figure 10.24

3. A. Sturtevant a. Gene mapping Based on frequency of expression between differen genes

IV. Detection of Problems A. Karyotyping How? B. Amniocentesis  Cellular and Chemical Analysis Figure 13.8

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

E. Fetal Tissue Sampling

F. Pedigrees == familial history Figure 10.9 Figure 10.10

Figure 10.25