1. Chromsomal Theory: Genetics Cytology
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. 1 pair of sex chromosomes
3 pairs of autosomes
                        
1 pair of sex chromosomes

4. w+ = wild type/red eye allele
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. YyRr x yyrr Unlinked Genes = show independent assortment 25% yyRr
50% parental types
50% recombinants

7. UNLINKED 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. = x 100 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 Linked Traits: usually X-linked traits
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:
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 4. Deletions 5. Translocations Metafemales
Turner syndrome
4. Deletions
Cri du chat syndrome
5. Translocations
chronic myelogenous leukemia (CML)

18. 6. Parental Imprinting 7. Genomic Imprinting 8. Fragile X Syndrome
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