Genotype(punett square)?

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1. Albinism occurs commonly in animals and it is always recessive to the "normal" pigmentation. Six brown and five albino mice born to parents which were like-wise brown and albino. What is the genotype of the brown parent? Explain.

Plz help me. What is the genotype of the brown parent?

Answer 1

the brown parent would have to be heterozygous (Bb) because to get an albino mouse you would have to get homozygous (bb) and one comes from each parent. so if the white parent would be (bb) and the brown parent would be (Bb) so that some of their children would be brown (Bb) and some would be albino (bb)

Answer 2

1. Given that the ratio of the offspring is close to 1 albino:1 brown we can conclude that the genotype of the parents are Aa and aa. Note that recessive phenotypes can only be manifested by the homozygous recessive genotype and that the other parent can never be homozygous dominant since there would be no albino had it been the case leaving us with the Aa genotype of the other parent. The cross would be as follow:

Aa x aa=1/2Aa(brown),1/2aa(albino)

As you can see in the 11 offspring 1/2(6) were brown and almost 1/2(5) were albino.

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