How to Determine Phenotype Based on Genotype in Mice

What would be the phenotype of a mouse with genotype gg?

A) Gray fur

B) Black fur

C) Gray fur with the black spot

D) Black fur with the gray spot

Answer:

The correct answer is B) Black fur.

When determining the phenotype of a mouse based on its genotype, it is essential to understand the concept of dominance in genetics. In the case of fur color in mice, the gene responsible for fur color has two alleles: G for gray fur (dominant) and g for black fur (recessive).

Since the genotype provided is gg, which means the mouse has two copies of the recessive allele for black fur (g), the phenotype of the mouse would be black fur. This is because the dominant allele (G) for gray fur would mask the presence of the recessive allele (g) in mice with Gg or GG genotypes, resulting in gray fur.

Therefore, in this scenario, a mouse with the genotype gg would exhibit the black fur phenotype. Understanding the relationship between genotype and phenotype is crucial in genetics and can help predict the observable traits of an organism based on its genetic makeup.