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? asked in Science & MathematicsBiology · 1 decade ago

Please answer this genetics Q and can you show me the punnet square?

In humans, the condition for normal blood clotting dominates hemophilia. Both alleles are sex-linked to the X chromosome. Two parents produce daughters who are all carriers and sons who are all normal. What are the probable genotypes and phenotypes of the parents? Thank you.

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  • Anonymous
    1 decade ago
    Favorite Answer

    H = normal dominant allele

    h = recessive allele for hemophilia

    Based on the information given, you can conclude that in order for two parents to produce daughters who are all carriers (XH Xh) and sons who are all normal (XH Y), the mother must be homozygous dominant (XH XH), and the father carries one recessive allele for hemophilia (Xh Y), a conditon referred to as hemizygous. Thus, the mother is phenotypically normal, and the father has hemophilia. The offspring are the result of the following crossing:

    (XH XH) x (Xh Y)

    Sorry, I have not perfected typing my punnet square, but this crossing will result in 100% of the females being carriers (XH Xh) and 100% of the males being normal (XH Y).

    Conclusively,

    PARENTAL GENOTYPES:

    XH XH (homozygous dominant female)

    Xh Y (hemizygous male)

    PARENTAL PHENOTYPES:

    Mother - normal

    father - hemophiliac

    I hope this helps!

    Source(s): biology major
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