Share
Explore BrainMass

Genetics Problems

(1) Two inbred strains of mice, one strain with black fur and one strain with brown fur, were crossed. All of the offspring had black fur. If the offspring are bred together, what percentage of their offspring will have black fur?

(2) Given the B and b alleles from the above question, and the T and t alleles which determine tail length (the allele T for a long tail is dominant over the allele t for a short tail), what are the phenotypes and genotypes that would result from a BbTt x BbTt crossing. Assume that the two genes assort independently.

Solution Preview

(1) Two inbred strains of mice, one strain with black fur and one strain with brown fur, were crossed. All of the offspring had black fur. If the offspring are bred together, what percentage of their offspring will have black fur?

It seems as if each of the two original strains of mice is homozygous for a different allele of a gene that determines fur color. Let's call these alleles B and b. B is the allele causing black fur and b is the allele causing brown fur. The offspring of the strains must have the genotype Bb (each inherited a B from the black parent and a b from the ...

$2.19