2)(8 points) Lobed wings (Xi) in Drosophila result from an x-linked allele that
ID: 163187 • Letter: 2
Question
2)(8 points) Lobed wings (Xi) in Drosophila result from an x-linked allele that is recessive to the allele for wild-type wings (x Give the types of the parents the following crosses: in Male parent Female parent Male offspring Female offspring Wild type Wild-type wild-type. 560 wild-type 250 lobed Lobed Wild-type 410 wild-type, 412 wild-type. 417 415 lobed Ice Wild type Lobed 753 lobed 761 wild-t Id. Lobed i Wild-type 610 wild-type 632 wild-type Male Parent 13) (5 points) Hemophilia in humans is due to an X-linked recessive gene. Both Mike and Tessa are healthy. A year after they married, Tessa gave birth to a son with hemophilia. Five years is later, she gave birth to a daughter with the same disease. Mike filed for divorce, claiming he not the father of the child. ls he justified in his claim of nonpaternity? Explain why. 14) (4 points) Sarah is colorblind in only one eye. Her husband has normal vision. Half of her sons are colorblind, but none of her daughters are. What is Sarah's genotype? Why is she colorblind in only one eye? 15) (6 points) only appears in males, even when females carry it. It is a. You observe a trait in a family that this? NOT on the X or Y What type of trait is b. You observe a trait in a family that is dominant in females, but recessive in males. What type of trait is this?Explanation / Answer
Answer:
12. The genotype of the male parent is the same as his phenotype for an X-linked trait. Because the male progeny get their X chromosomes from their mother, the phenotypes of the male progeny give us the genotypes of the female parents.
(a) Male parent is X+Y. Because the male offspring are 1:1 WT:lobed, the female parent must be X+XL. You can use a Punnett square to verify that all the female progeny from such a cross will have WT wings (they get the dominant X+ from dad).
(b) Male parent is XLY; female parent is X+XL.
(c) Male parent is X+Y; female parent is XLXL.
(d) Male parent is XLY. Because the male offspring are all WT, the female parent must be X+X+.
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