Q. 235.0( 4 Votes )
Study the given p
(a) The given trait is dominant as it is getting expressed in all the generation.
(b) The trait is autosomal because the male and female progeny of 2nd generation is equally getting affected by the disease or trait.
(c) Let Mm (dominant) denote the one affected by trait.
Genotype of parents shown in generation 1: Mm (affected male) and mm (healthy female)
Genotype of 3rd child in generation 2: Mm (affected male child)
Genotype of 1st grandchild in generation 3: Mm (affected female).
(a) Let XX denote female, and XY denote male.
The genotype of 4: XXh (XXh shows that the female is a carrier of haemophilia as Xh is suppressed by another X gene, h show the gene for haemophilia.
The genotype of 5: XhY (XhY shows a haemophilia affected male as Xh is expressed dominantly over gene Y.)
The genotype of 6: XY (XY shows a healthy male; also male cannot act as a carrier of the haemophilic gene.)
(b) Genotype of individual 14 is XhX (female carrier of haemophilia)
and of individual 15 is XY (healthy male).
The probability of their first child being a haemophilic male is: 1/4
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