1. The Chromosome Theory of Inheritance Chpt. 15 Chpt. 15.

2. 1866 Mendel’s paper 1875 process of mitosis revealed 1890 process of meiosis revealed 1902 realization that chromosomes were Mendel’s “factors” Putting the pieces together

3. Sex chromosomes- Autosomes

4. --> vary within species -->-->-->

5. Sex chromosomes -

6. In 1902 Sutton suggested that "the association of paternal and maternal chromosomes in pairs and their subsequent separation during the reduction division...may constitute the physical basis of the Mendelian law of heredity." His "The Chromosomes in Heredity" was published in 1903.

7. Walter Sutton 1902 Genes have specific locations (loci) on chromosomes chromosomes undergo segregation and independent assortment. The Chromosome Theory of Inheritance

8. tracking 2 genes on different chromosomes in their homologous pairs.

9. Thomas Hunt - Morgan 1 st to associate specific genes on specific chromosomes

10. Thomas Hunt Morgan Utilized:Drosophila melanogaster fruit fly 3 pairs autosomes 1 pair sex chromosomes

11. Thomas Hunt Morgan Utilized: Drosophila melanogaster can reproduce a generation in two weeks.

12. Fruit Fly Chromosomes

13. Genetic Symbols Mendel - use of uppercase or lowercase letters. T = tall t = short Morgan: symbol from the mutant phenotype (for fruitflies). + = wild phenotype (predominant)

14. Examples Recessive mutant: w = white eyes w+ = red eyes or + = red eyes

15. Examples “Mutant” = Cy = Curly wings Wild Type = Cy+ = Normal wings

16. Evidence for Sex Linkage female red eyes X male white eyes F1 --> 4:0 RED F1 --> 4:0 RED You would expect this with Mendel… would you not?

17. Evidence for Sex Linkage female red eyes X male red eyes F2 --> 3:1 BUT ONLY males had white eyes?? F2

18. eye color linked to gender

19. Examples Recessive mutant: w = white eyes w+ = red eyes or + = red eyes

20. eye color linked to gender 50% males had red eyes. 50% males had red eyes. 50% males had white eyes. 0% females had white eyes.

21. Evidence for Sex Linkage 50% males had red eyes. 50% males had red eyes. 50% males had white eyes. 50% males had white eyes. 0% females had white eyes. 0% females had white eyes.

22. Fruit Fly Chromosomes

24. Linked Genes (not sex-linked genes) Genes are on the same chromosome, therefore passed along as a “unit”Genes are on the same chromosome, therefore passed along as a “unit” these DEVIATE from Mendel’s “norm” A B uRuRatios mimic monohybrid crosses.. But it is a dihybrid cross.

25. Linked Genes Linked Genes (not x-linked)1:1:1:1 5:5:1:1

26. IF genes are linked, we would NOT expect any offspring to have different characters from that of the parents… THAT was not the case though, the offspring were, in fact different

27. “Well now, THAT’s confusing

28. Linked Genes Linked Genes (not x-linked)

29. Something’s goofy

30. Recombination due to crossing over in linked genes

31. “YES!!! I remember this stuff!!”

33. u Breaks up linkages and creates new ones. u Recombinant offspring formed that doesn't match the parental types. Crossing-Over

34. Alfred Sturtevant

36. Recombination Frequency= # of recombinants total offspring gives a rough estimate of how often recombination occurs. gives a rough estimate of how often recombination occurs. used to map genes in relation to one another. used to map genes in relation to one another. X 100

38. Recombination Frequency= The farther apart two genes, the higher the probability that a X-over will occur. The higher the Recombination Frequency

39. “YES!!! I remember this stuff!!”

40. Map of 3 genes relative to each other (genes: b, r, vg) b - vg = 17 r - vg = 9.5 b - r = 7.5

41. Map of 3 genes relative to each other b - vg = 17 r - vg = 9.5 b - r = 7.5 7.5 bvg 17% (genes: b, r, vg)

42. Map of 3 genes relative to each other b - vg = 17 r - vg = 9.5 b - r = 7.5 7.5 brvg 17% (genes: b, r, vg)

43. Map of 3 genes relative to each other b - vg = 17 r - vg = 9.5 b - r = 7.5 7.5 brvg 9.5 17% (genes: b, r, vg)

44. Map of 3 genes relative to each other

47. Gene Map - Relative position using map units.Relative position using map units. Obtained from Recombination Frequency DataObtained from Recombination Frequency Data

51. Calico Cats.

53. u Result - body cells are a mosaic of X types.