In mammals, the Sry gene on the Y chromosome is instrumental in the male sex determination process. However, in Drosophila, the Y chromosome is not associated with male sex determination, but it contains genes required for sperm development in the adult. The copy number of the X chromosome is linked to sex determination. Drosophila with two X chromosomes (e.g., XX) are female, and those with one X chromosome (e.g., XY) are male.
What would be the resultant phenotype of an XO Drosophila genotype?
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a
A fertile female
b
A sterile female
c
A fertile male
d. None of the above
b) A sterile female
b. A sterile female
To determine the resultant phenotype of an XO Drosophila genotype, we first need to understand the sex determination mechanism in Drosophila. In Drosophila, the presence of two X chromosomes (XX) typically results in a female phenotype, while the presence of one X chromosome (XY) typically results in a male phenotype.
In an XO genotype, the absence of a second X chromosome signifies a male genotype. Therefore, the resultant phenotype of an XO Drosophila genotype would be a fertile male. This is because the presence of the Y chromosome contains genes necessary for sperm development, which allows for fertility.
So, the correct answer is:
c. A fertile male