In Drosophila, the X chromosomes may become attached to one another such that they always segregate together. Some flies thus contain a set of attached X chromosomes plus a Y chromosome.
A. What sex would a fly like this be? Why?
B. Given the answer to (A), predict the sex of the offspring that would occur in a cross between this fly and a normal one of the opposite sex
A) In Drosophila, Y chromosome is not involved in sex determination, determining sex is attained by a balance of female contributing factor on the X chromosome and male contributing factor on the autosomes. Usually, drosophila have either one or two X chromosomes and two sets of autosomes. The drosophila fly is male, if there is one X chromosome in a diploid cell. The drosophila fly is female, if there are two X chromosomes in a diploid cell. Thus, XXY Drosophila is female.
B)Cross: XXY(female) X XY(normal male)
X | Y | |
XX | XXX (super female) | XXY (female) |
X | XX (female) | XY (male) |
XY | XXY (female) | XYY (male) |
Y | XY (male) | YY (dies) |
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