Mouse Genetics

Key Vocabulary Words:

Trait

Breed

Genotypes

Phenotypes

Dominant

Recessive

Homozygous

Heterozygous

Punnet Square

Part 1 Observation - Go through Observing Patterns of Inheritance portion of the Exploration Guide.

Try to answer these questions based on your observations:

1. Which of the following is true about the genotype of the mouse shown below?

2. Two black-fur mice are bred, and have the litter shown below. What is the most likely explanation for the presence of the white-fur offspring?

3. Two mice with white fur are bred. What will be true of the offspring?

4. Which of the following is a possible litter for two heterozygous black mice?


Part 2 Draw Punnett squares for the following breeding pairs. Write down the percentage of the phenotypes that the Punnett square predicts.

Breed a two homozygous black mice / Breed two homozygous white
Breed two heterozygous black mice / Breed a heterozygous black mouse with a white mouse

Go back to the Explore Learning and breed each pair at least 10 times. Record the results of the breeding pairs.

Breeding Pair / Number of Black mice / Number of White mice
Homozygous Black Mice
Homozygous White Mice
Heterozygous Black Mice
Herozygous black w/ homozygous white

Compare the results of each breeding pair with the predictions from the Punnett squares.

1. Did the Punnett square correctly predict the outcome of each breeding pair? Explain?

2. You take one of the mice. It’s white. Explain in your own words why the mouse is white.