Question

A cross in Drosophila involved the recessive, X-linked genesyellow(y), white(w), and cut(ct). A yellow-bodied, white-eyedfemale with normal wings was crossed to a male whose eyes and bodywere normal but whose wings were cut. The F1 females were wild typefor all three traits, while the F1 males expressed the yellow-bodyand white-eye traits. The cross was carried to F2, and only maleoffspring were tailed

Phenotype - Male offspring
y + ct - 9
+ w + - 6
y w ct - 90
+ + + - 95
+ + ct - 424
y w + - 376
y + + - 0
+ w ct - 0


a) what is the genotype of F1 parents?
b) construct a map assuming the white is at locus 1.5 on theX-chromosome

Which gene is in the middle? answer white

	yellow (y)
	cut (ct)
	white (w)

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Part C

The white gene is located at map position 1.5 on the Xchromosome, between yellow and cut. Use the datato determine the map positions of yellow andcut.

What is the map position of cut (ct)? Enteryour answer to one decimal place (example: 33.4 or 10.0).

20.0

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Part D

What is the map position of yellow (y)? Enteryour answer to one decimal place (example: 33.4 or 10.0).

0.0

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Part E

Were any double-crossover offspring expected? answer is yes

Were any double-crossover offspring expected?

	yes
	no

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Part F

How many double crossover offspring were expected? how do i findthis number

Enter answer as a whole number (round up if necessary).