Question

A male mouse with a grey coat is mated with an albino female. Their six offspring all have grey fur. The albino female is then mated with a second grey male mouse. Four of the seven offspring in this litter are albino.

1.What are the probable genotypes of the three-parent mice?
2. A male from the first litter is mated with a grey female from the second litter. What is the expected ratio of phenotypes among the offspring?

Answer 1

The probable genotypes of the three-parent mice are AaCc, aacc, and AaCc. When a male from the first litter (genotype AaCc) is mated with a grey female from the second litter (genotype AaCc), the expected ratio of phenotypes among the offspring is 9 Agouti, 3 Grey, and 4 Albino.

Step-by-step explanation:

The probable genotypes of the three-parent mice can be determined based on the information provided:

1. The male mouse with grey coat = AaCc (heterozygous for both genes)
2. The albino female = aacc (homozygous recessive for both genes)
3. The second grey male mouse = AaCc (heterozygous for both genes)

Therefore, the probable genotypes of the three-parent mice are AaCc, aacc, and AaCc.

2. When a male from the first litter (genotype AaCc) is mated with a grey female from the second litter (genotype AaCc), the expected ratio of phenotypes among the offspring can be determined using the Punnett square method:

The expected ratio of phenotypes among the offspring is:
9 Agouti (mottled agouti coat color)
3 Grey (solid grey coat color)
4 Albino (no pigment production)