In hamsters, the brown color of the coat is determined by one dominant gene, and the apricot by another dominant gene. These genes are located in different pairs of chromosomes; their recessive alleles lead to the appearance of a white color. If both non-allelic dominant genes are present in the hamster’s genotype, a new sign appears – black coloration.
From the crossing of an apricot male with a brown female, a calf with white hair was born. Establish genotypes of parental individuals. What offspring can they expect in the future?
We introduce the notation of genes; for individuals with a black color, we indicate the phenotypic radical:
A – brown color;
a – white color;
B – apricot blossom;
b – white color;
A – B– – black color.
– We will establish the genotypes of the parental individuals. Previously, for the brown female, the following phenotypic radical can be written: A – bb, for the apricot male: aaB–.
Their white-haired cub has the aabb genotype, and he inherited from each parent one recessive gene from each allelic pair. Therefore, the female genotype is Aabb, and the male is aaBb.
So, in this parental pair the birth of cubs with black, brown, apricot and white hair is equally probable (25% each).
Answer: The probability of giving birth to cubs with black hair is 25%, with brown – 25%, with apricot – 25%, with white – 25%.
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