In a cross between two agouti mice of genotype AaBb, what is the expected phenotypic ratio?

In a cross between two agouti mice of genotype AaBb, what is the expected phenotypic ratio?

• A. 9 agouti: 3 black: 4 albino
• B. 9 agouti: 3 albino: 4 black
• C. 3 agouti: 1 black: 1 albino
• D. 9 agouti: 3 black: 3 albino

Answer: (A)

The correct answer, which indicates a phenotypic ratio of 9 agouti: 3 black: 4 albino, is derived from the principles of Mendelian genetics, particularly when considering the inheritance of two traits governed by two different genes. In mice, the agouti color (A) is typically dominant over the black color (a), while the albino condition (B) is also dominant over the non-albino condition (b). In the cross between two agouti mice of genotype AaBb, we can use a Punnett square or a dihybrid cross analysis to evaluate the outcomes. When you cross AaBb with another AaBb, there are four possible combinations for each gene: A or a for the first gene affecting coat color, and B or b for the second gene affecting pigmentation. The resulting combinations yield the following potential phenotypes: 1. **Agouti (A-B-)**: Represents mice that have at least one A allele and one B allele. 2. **Black (A-bb)**: Represents mice that have at least one A allele but are homozygous for the albino allele, resulting in black fur. 3. **Albino (aaB-)**: Represents mice that are homo

The correct answer, which indicates a phenotypic ratio of 9 agouti: 3 black: 4 albino, is derived from the principles of Mendelian genetics, particularly when considering the inheritance of two traits governed by two different genes.

In mice, the agouti color (A) is typically dominant over the black color (a), while the albino condition (B) is also dominant over the non-albino condition (b). In the cross between two agouti mice of genotype AaBb, we can use a Punnett square or a dihybrid cross analysis to evaluate the outcomes.

When you cross AaBb with another AaBb, there are four possible combinations for each gene: A or a for the first gene affecting coat color, and B or b for the second gene affecting pigmentation. The resulting combinations yield the following potential phenotypes:

1. Agouti (A-B-): Represents mice that have at least one A allele and one B allele.

2. Black (A-bb): Represents mice that have at least one A allele but are homozygous for the albino allele, resulting in black fur.

3. Albino (aaB-): Represents mice that are homo