02.25.2021
Experiment leads: Yutong
In this visit, students explored the concepts of genetics and probability using a simulated experiment of mouse breeding. The visit started with the example of dog breeding, in which the offspring of two purebred dogs would carry traits from both parents. Then, we explained the phenomenon by introducing the concept of allele genes as well as dominant and recessive genes. When two homozygous parents (i.e., HH and hh) breed, the offspring will be a heterozygous (Hh) that only shows the trait coming from the dominant gene H. However, the offspring of Hh may not only express the dominant trait, depending on the parents.
After the introduction, we guided the students through a simulated mouse breeding experiment on Gizmos, where the student first started with an experiment with one trait, the hair color of mice (Figure 1). The offspring of a black hair (FF) and white hair (ff) parent only has one possibility, heterozygous black hair (Ff). We asked the students what if they expect to see black hair, white hair, grey hair, or patterned offspring. Then we asked the students to put two heterozygous mice on the parent positions and breed until they get 500 offspring. It turned out that ¾ of the offspring will appear to have black hair and ¼ of the offspring will show white hair. We walked through the reasoning using the Punnett square and explained the concept of probability. We explored more examples including FF x Ff, Ff x ff, and ff x ff. From this point, the students know how to predict the probability of a certain trait showing up in the offspring.
Figure 1. Simulated mouse breeding experiment with one trait (black/ white hair).
We then conducted a more advanced simulated breeding experiment which involved two traits, hair color and eye color (Figure 2). Using the Punnett square, students were able to predict combinations and the probability of the offspring.
Figure 2. Simulated mouse breeding experiment with two traits (black/ white hair).