Genetics of Fur Color in Mice
a. What is the genotype of the gametes produced by the brown-furred parent?
A) The genetics of the brown-furred parent's offspring is (b). Because brown fur is a recessive trait, the brown-furred parent must be homozygous recessive, which means it can only produce gametes bearing the recessive allele.
b. What is the genotype of the brown-furred parent?
B) The brown-furred parent's gene is (bb), homozygous recessive.
c. What is the genotype of the black-furred parent?
C) Because the black-furred father is homozygous for the dominant allele, its genotype is (BB).
d. What is the genotype of the black-furred offspring?
D) The black-furred offspring's DNA is (Bb). Because the brown-furred parent can only create recessive alleles and the black-furred parent can only produce dominant alleles, all offspring must be heterozygous dominant.
For the genetics of fur color in mice, the dominance of black fur (B) over brown fur (b) plays a crucial role in determining the offspring's appearance. When breeding a brown-furred parent with a homozygous black-furred parent, all offspring will have black fur due to the dominant nature of the black allele.
In the scenario described, the brown-furred parent is homozygous recessive (bb), meaning it can only produce gametes carrying the recessive brown allele (b). On the other hand, the black-furred parent is homozygous dominant (BB), producing gametes with the dominant black allele (B).
When the two parents breed, all the offspring will inherit one black allele (B) from the black parent and one brown allele (b) from the brown parent, resulting in a genotype of Bb. This genetic makeup determines the black fur color of the offspring.
Understanding the principles of genetic inheritance, specifically the dominance and recessiveness of alleles, helps predict the outcomes of breeding experiments and describes the genetic makeup of different generations of organisms.