In fruit flies genes pr and vg code alleles are as follows f

In fruit flies, genes pr and vg code alleles are as follows for the \"prickly\" and \"vestigial wings\" traits. The alleles are as follows: pr = prickly back pr^*= smooth back (no prickly hairs) vg = normal wing vg^* = vestigial (smooth wing) You perform a test cross between a fly with genotype pr pr^* vg vg^* and a fly with genotype pr pr vg vg yields. Draw a dihybrid Punnett square predicting the progeny of this cross. State all predicted phenotypic outcomes and the expected proportion of each. Below are the actual phenotypic outcomes from the testcross. Generate a null hypothesis that you can test to see if the pr and vg alleles are linked (located the same chromosome). Write your null hypothesis below. Fill in the \"expected\" column above with the number of each phenotype you would obtain your null hypothesis were correct.

Solution

Answer:

1). pr+ pr vg+ vg   X pr pr vg vg—Test cross

pr vg

pr+ vg+

pr+ pr vg+ vg (25%, Smooth back, vestigial wing)

pr+ vg

pr+ pr vg vg   (25%, Smooth back, normal wing)

pr vg+

pr pr vg+ vg   (25%, Prickly back, vestigial)

pr vg

pr pr vg vg   (25%, Prickly, normal wing)

2).

Phenotype

Expected

Observed

Prickly, normal wing

497.5

874

Smooth back, vestigial wing

497.5

906

Prickly back, vestigial wing

497.5

112

Smooth back, normal wing

497.5

98

	pr vg
pr+ vg+	pr+ pr vg+ vg (25%, Smooth back, vestigial wing)
pr+ vg	pr+ pr vg vg   (25%, Smooth back, normal wing)
pr vg+	pr pr vg+ vg   (25%, Prickly back, vestigial)
pr vg	pr pr vg vg   (25%, Prickly, normal wing)