1. Chromsomal Theory: GeneticsCytology 1860 = Mendel’s theories of heredity 1875 = cytologists work out mitosis 1890 = cytologists work out meiosis 1900 = Correns, DeVries and von Seysenegg rediscover Mendel’s work

2. 1902 = Sutton and Bovari notice parallels between Mendel’s theories and the behavior of chromosomes Thomas Hunt Morgan: starts doing experiments with Drosophila melanogaster

3. 3 pairs of autosomes 1 pair of sex chromosomes

4. Wild Type = normal and most frequently observed phenotype Mutant Type = phenotypes that are alternatives to the wild type w = white eye allele w+ = wild type/red eye allele

5. Eye Color: located on the X- chromosome = sex linked P: w+w+ x w 100% w+w (all red eye) Linked Genes = located on the same chromosome and tend to be inherited together; do not assort independently

6. Unlinked Genes = show independent assortment YyRr x yyrr 25% YyRr 25% yyrr 25% yyRr 25% Yyrr 50% parental types 50% recombinants

7. Parental type = same phenotype as one of the parents Recombinants = a phenotype that differs from either parent 50% recombination or better means genes assort randomly UNLINKED

8. If recombinants are less than 50%, genes are probably linked. Recombination frequency = % of crossing over Recombination Frequency = recombinants total offspring x 100

9. * Probability of crossing over is directly proportional to the distance between the genes. 1 map unit (centimorgan) = 1% recombination frequency

12. Sex Chromosomes: heterogametic sex homogametic sex Sex Linked Traits: usually X-linked traits hemophilia color blindness Duchenne’s muscular dystrophy

13. Pedigree for Color Blindness:

14. X-Inactivation in Females: Lyon Hypothesis Barr Bodies

15. Chromosomal Alterations: Nondisjunction Aneuploidy Polyploidy Alterations of Chromosome Structure Breakage Duplication Translocation Inversion

16. Results of Chromosomal Alteration: 1. General Down’s syndrome = trisomy 21 Patau syndrome = trisomy 13 Edward’s syndrome = trisomy 18 2. In Males Klinefelter syndrome Extra Y

17. 3. In Females Metafemales Turner syndrome 4. Deletions Cri du chat syndrome 5. Translocations chronic myelogenous leukemia (CML)

18. 6. Parental Imprinting Prader-Willi syndrome Angelman syndrome 7. Genomic Imprinting 8. Fragile X Syndrome 9. Uniparental Disomy

19. Exceptions to Chromosomal Theory of Inheritance: Extranuclear genes Plants