1. Drosophila Genetics
Inheritance of Body Color
B. Three Point Testcross

3. Inheritance of Body Color: Phenotypes of Parents
Letter
Gender
Body Color A
Female
Beige body B C
Male D
Yellow body E

4. Inheritance of Body Color: Crosses
A x C B x C D x C
A x E B x E D x E
Score each fly for gender and body color
Beige
Yellow

5. Distinguishing Male and Female Fruit Flies
Male body size is smaller than female
Male abdomen is tapered and darker than female abdomen
Males have sex combs at first joint on front legs
You MUST be able to see sex combs on any fly you identify as male!

6. Three Point Testcross X bl+ vg+ bw+ bl vg bw PARENTALS: bl+ vg+ bw+
F1:

7. Three Point Testcross bl vg bw X Black, vestigial, Brown Males
F1 Females
bl+ vg+ bw+
bl vg bw
F2 Generation

8. Three Point Testcross: Possible Phenotypes
Body Color
Wing Length
Eye Color
Beige
Long
Red
Black
Vestigial
Brown

9. Three Point Testcross: F2 Offspring
Score each fly for body color, wing shape and eye color.

10. Wild Type Versus Mutants
Body Color
Wild type: Beige
Mutant: Black

11. Wild Type Versus Mutants
Wing Shape
Wild Type: Long
Vestigial

12. Wild Type versus Mutants
Eye Color
Wild Type: brick red
Mutant: Brown “red-brown” (use high intensity light to distinguish)
Carolina Biological

13. Viewing the Fruit Fly

14. Nap Time

15. How to anesthetize a fly