Pedigree Analysis

Pedigree analysis is a method of assessing disease risk and determining genotypes of people within a family line. Therefore, pedigree analysis is an application of basic Mendelian genetics, which you saw a video about for today.

Groups: Number Groups

Purpose:

    • To develop the skills needed to apply basic Mendelian genetics, including the use of punnet squares, reading and creating pedigree charts, and probability assessment

    • Clarify any confusion over Mendelian genetics by making sure all students can apply the concepts

Procedure:

    1. Get into your number groups. These were the groups you had for the very first activity.

    2. Within your group, compare your day of birth (for example, I was born June 7, so my day of birth is "7"). Divide into roles as follows:

        1. The member of the group with the smallest numbered birth day: time-keeper The time-keeper makes sure the group stays focused on the activity and completes the steps on time.

        2. Second-smallest numbered member: presenter The presenter will speak for the group during the whole class discussion.

        3. Member of group with the largest numbered day of birth: leader The leader makes sure every voice is heard, and helps encourage the group to stay on-task

        4. Note there is no recorder for this activity because everyone needs to fill out their own handouts and turn them in

    3. I will give each group a set of handouts. (I will give you a copy of the handouts, but if you want to look at them ahead of time, they are attached below)

    4. Questions 1-3 on the handout: These questions focus on creating Punnet squares, and using them to predict the traits of future offspring. Remember, we calculate the probability of two independent events by multiplying the probability of one of them by the probability of the other. Take ten minutes to go through the questions together. Afterward, we will discuss the answers as a class.

    5. Questions 4: This question simply applies the above concepts to multiple genes at the same time. If you have extra time, you may go through this question, but it is not required. We may come back to it at the end of class if we finish everything else.

    6. Question 6: Once you have mastered creating and interpreting Punnet squares, the concepts can be applied to pedigrees (family trees, essentially), which are used to understand how genetic diseases are transmitted, and to predict the likelihood that they will be found in later generations. Take ten minutes to go through the question together. Afterward, we will discuss the answers as a class.

Take-home Messages

    • You should be able to create and interpret Punnet Squares

    • You should be able to calculate the probability that offspring of two individuals of known genomes will have particular allele combinations

    • You should be able to create and interpret pedigrees

    • These skills and concepts can be applied to real-world case studies and situations