Drosophila Genetics Inheritance of Body Color B. Three Point Testcross

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

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

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!

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

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

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

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

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

Wild Type Versus Mutants Wing Shape Wild Type: Long Vestigial

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

Viewing the Fruit Fly

Nap Time

How to anesthetize a fly