4. Dominant allele with recessive lethality
(black)
Dominant allele with recessive lethality

5. Dominant allele with recessive lethality
1 gene with 2 alleles
we’ve seen 4 cases:
Dominant allele with recessive lethality
1 AA : 2 Aa : 1 aa
complete dom/rec dom dom rec
incomplete dominance dom blend dom-rec rec
codominant dom dom1+ dom dom2
recessive lethal (dom. marker) dead dom rec

6. IC. Genes with multiple alleles
1 Gene with 3 alleles
IA & IB are co-dominant; i is recessive

7. IC. Genes with multiple alleles
Hierarchy of dominance:
C > cch > ch > c

8. IC. Genes with multiple alleles
chinchilla
cch

9. IC. Genes with multiple alleles
chinchilla
cch

10. IC. Genes with multiple alleles
chinchilla
cch
himalayan ch

11. IC. Genes with multiple alleles
Hierarchy of dominance:
C > cch > ch > c

12. IC. Genes with multiple alleles

13. IC. Genes with multiple alleles
A short list of the 1587 known mutant alleles of the
Drosophila melanogaster eye color gene w (white)

14. ID. Two genes, interacting
Back to
2 genes
TIME

18. ID. Two genes, interacting

19. A/A ; B/B a/a ; b/b A/a ; B/b self-cross

22. ww
m+ & m

23. Coat color:
Genes
A, B, C, D, E, S

24. A

25. AY

27. B

28. cc C

29. C

30. C

31. D

32. E e

33. E e

34. ee
B & b

36. cc
B & b

37. Agouti,
not Yellow
(A, not AY)

38. cc
A & a

39. cc
A & a

40. Genotype ratios: 1:2:1:2:4:2:1:2:1
(“A” here =AY) X X X X
Phenotype ratios: 9:3:3:1
Genotype ratios: 1:2:1:2:4:2:1:2:1
AYAY X X X
CC:Cc:cc
6:3:3

41. Hair color genes- -
A, B, C, D, E & … S

42. II. Mention epistasis versus suppression

43. Genotype -> Phenotype
III.
Genotype -> Phenotype
. . . but with interactions of unknown other genes, environment,

48. Lack of
Penetrance
Variable
Expressivity
Lack of
Penetrance

51. .4