27 A rare dominant autosomal mutation Wresult wooly, curled hair in some Europea

Question

27 A rare dominant autosomal mutation Wresult wooly, curled hair in some European pedigrees. A woman with wooly hair with blood group O mar- ries a man with straight hair (ww) with blood group AB. The genes are in different chromosomes. (a) What are the chances that the mating will produce a wooly-haired, group B child? (b) What are the chances that the mating will produce a straight-haired, group B child? (c) If three straight-haired children with blood group A are born to these parents, what are the chances that the next child born will be wooly- haired and blood group B?

Explanation / Answer

Wooly curled har = Ww
Straight hair = ww

Parental cross: Ww OO X ww AB
Gametes: (WO)(wO) X (wA)(wB)
Progeny: WwAO wwAO WwBO wwBO

a.
The probability for wooly haired group B child, WwBO = 1/4

b.
The probability for straight haired group B child, wwBO = 1/4

c.
Ideally, the probability for each child with different genotype to be born is same irrespective of the number of the birth.
This is because the fusion of gametes for each child is an independent and random event.
= 1/4

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