A mutation in mice called abnormal head (abh) causes defects in head development

Question

A mutation in mice called abnormal head (abh) causes defects in head development. For the following possibilities (a-c), state whether the heads of F1 will be mutant or normal when true-breeding diploid parents if the following genotypes are crossed. Indicate if the male or female F1 progeny will differ. Wild-type female and x mutant male                                                                Mutant female and x wild-type male A. if abh is an autosomal recessive mutation                                       B. if abh is an autosomal dominant mutation C. if abh is a sex-linked recessive mutation A mutation in mice called abnormal head (abh) causes defects in head development. For the following possibilities (a-c), state whether the heads of F1 will be mutant or normal when true-breeding diploid parents if the following genotypes are crossed. Indicate if the male or female F1 progeny will differ. Wild-type female and x mutant male                                                                Mutant female and x wild-type male A. if abh is an autosomal recessive mutation                                       B. if abh is an autosomal dominant mutation C. if abh is a sex-linked recessive mutation

Explanation / Answer

Case1: abh is auto. recessive a) wild femal X mutant male: since the mutaion is an autosomal , sex has nothing to do with it. So, the effect will be the same on both male and femal. also , the recessive allele will be masked by the normal, dominant allel, there will be no effect on the offspring. b) The same as above if the cross is between Mutant femaleXwild type male Case2: abh is auto dominant a) Wild Female x mutant male: since the offsprings (regardless of sex) will have one allel from the mutant father that is dominant. As a result all the offspring (male and female ) will be mutant because they are hetrozygote . b) the same as above Case3: abh is x resessive a) Wild female X mutant male: males has only one x chromosome and they give it to their daughters. The sons will get the x chromosome from their mother which is wildtype. So the males will be normal. The females get one mutant x from father and one normal/wildtype from mother . Since the the gene is recessive gene, the females also will be normal but they are carriers. b) Mutant female X wildtype male: all the sons get x-chromosome from mother which is mutant; as a result, all the males will have deffected head development. The female gets one normal x- chromosome from father and one mutant from mother and will be carrier but will have normal head development.

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