The Notch mutation is a deletion on the X chromosome of Drosophila melanogaster

Question

The Notch mutation is a deletion on the X chromosome of Drosophila melanogaster. Female flies heterozygous for Notch have an indentation on the margins of their wings; Notch is lethal in the homozygous and hemizygous conditions. The Notch deletion covers the region of the X chromosome that contains the locus for white eyes, an X-linked recessive trait.

Express your answer as fractions (or 0), separated by dashes, no spaces. Do not include the phenotypes, but your answer should reflect this order:

white-eyed females, white-eyed Notch females, red-eyed Notch females, wild-type females, white-eyed males, white-eyed Notch males, red-eyed Notch males, wild-type males

Part A: If a red-eyed, Notch female is mated with a white-eyed male, what fraction of progeny are expected to be white-eyed females, white-eyed Notch females, red-eyed Notch females, wild-type females, white-eyed males, white-eyed Notch males, red-eyed Notch males, wild-type males?

Part B: If a white-eyed, Notch female is mated with a red-eyed male, what fraction of progeny are expected to be white-eyed females, white-eyed Notch females, red-eyed Notch females, wild-type females, white-eyed males, white-eyed Notch males, red-eyed Notch males, wild-type males?

Part C: If a white-eyed, Notch female is mated with a white-eyed male, what fraction of progeny are expected to be white-eyed females, white-eyed Notch females, red-eyed Notch females, wild-type females, white-eyed males, white-eyed Notch males, red-eyed Notch males, wild-type males?

Explanation / Answer

(A)

XNX+ x XwY

1/3 white eyed females , 1/3 white eyed Notch females , 1/3 wild-type females and 1/3 wild-type males

(B)

XNXw   x    X+Y

1/3 Notch red-eyed females , 1/3 wild type females and 1/3 white eyed females

(C)

XNXw   x   XwY

1/3 Notch white-eyed females , 1/3 white eyed females and 1/3 white eyed males

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