Concept explainers
a.
To determine: The expected proportions of
Introduction: The hair color in humans is regulated by two interacting genes. The pigment melanin is present in both types of hair that is brown hair as well as blond hair; however it is present more in brown haired people. Blond hair (b) is recessive to brown hair (B). The synthesis of melanin is coded by another gene having two alleles. The (M) allele allows the synthesis of melanin whereas the (m) allele prevents it. The genotypes (mm) are albino. The pigment melanin is present in both types of hair that is brown hair as well as blond hair; however it is present more in brown haired people. Blond hair (b) is recessive to brown hair (B).
b.
To determine: The expected proportions of phenotypes in children of BbMm ×BbMm.
Introduction: The mating has taken place between two doubly heterozygous individuals. Both of them have a genotype of BbMm that is both will have brown hair gene as well as gene for melanin synthesis.
c.
To determine: The expected proportions of phenotypes in children of BbMm and bbmm.
Introduction: One of the parents have a genotype of BbMm that is will have brown hair gene as well as gene for melanin synthesis and the other parent is albino.
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