End of lecture question In Drosophila, miniature wings are a recessivetrait You
ID: 302209 • Letter: E
Question
End of lecture question In Drosophila, miniature wings are a recessivetrait You want to determine ifthe gene is located on an autosome or the X chromosome so you perform a reciprocal cross. Design the crosses and show the F1 progeny results if the trait is inherited as autosomal recessive or X -linked recessive - The following F1 progeny were obtained from the experiment: . Normal female x miniature male ? 50% normal male and 50% normal female . Normal male x miniature female ? 50% miniature male and 50% normal female - Is the gene on the X chromosome?Explanation / Answer
The gene is absolutely on X chromosome; And the disorder is X-linked recessive. To show how,
If the disorder is X-linked recessive
Scenario 1 :
XX (Normal female) x XcY (Miniature male)
F1 results- XXc, XXc, XY, XY
50% normal male and 50% normal female.
Scenario 2 :
XY (Normal male) x XcXc( Miniature femlale)
F1 results- XXc, XcY (Affected) , XXc, XcY (Affected)
50% normal female and 50% miniature male)
[Note- In X-linked recessive disorder both the alleles has to be fauty(XcXc) to be diseased in the case of female. In the case of male if the present one X allele is faulty(XcY) then the person is diseased.]
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