Lesson Sequences to Teach Genetics With HHMI BioInteractive Resources
Genetics and patterns of inheritance are key topics to cover in a biology course. I used to struggle with finding examples to explain these in class, as well as with finding activities for students to practice working with these concepts. Inevitably, I ended up with the old and classic green-and-yellow pea examples or inventing mutations in a hypothetical gene. That is, until I discovered the wide variety of inheritance activities that BioInteractive has available.
I teach different levels of biology in a private bilingual school in Mexico City, so I will suggest different activities for different levels and make some recommendations for online class adaptations. All of my lesson sequences described here can be used in an online classroom; the activities I selected are available in Google Docs versions for easier use.
In my introductory course, I cover Mendelian inheritance in three 50-minute classes.
- During the first class, I do a Mendel storytelling session (20–30 min). I explain how Mendel became a monk, how his sister gave him her dowry so he could finish studying, and how devoted he was to science. I use this story to introduce some key concepts and terms like “trait,” “characteristic,” “filial,” “dominant,” “recessive,” and “codominant.” My students create a glossary of terms that they keep adding to throughout the semester.
- During the second class, we watch the Popped Secret: The Mysterious Origin of Corn BioInteractive short film and start the activity “The Teosinte Hypothesis,” which students work on in small teams. In online classes, you can create breakout rooms in Zoom for this. “The Teosinte Hypothesis” is an activity designed to help students comprehend how genes are inherited and to have them work with Punnett squares, frequencies, proportions, and genotypes.
- During the third class, we continue the “Teosinte Hypothesis” activity. Depending on the amount of time that I have and the content I need to cover, I do the parts of the activity using Punnett squares for monohybrid and dihybrid crosses of teosinte and maize genes, which include an analysis of how this provides evidence of ancestry. Students are amazed by the mix of genes in the illustrations when doing the crossings. Their questions include asking if the corn we eat now is transgenic and if teosinte is a plant that still exists. This case study always makes them connect to the topic because we eat a lot of corn in our daily diet. Since this is an introductory class, we do not complete the portion of the activity looking at three genes, as that’s overwhelming for students. Some students share results as we check the activity as a group; this works well for online classes too.
I’ve also used another great activity called “Mendelian Genetics, Probability, Pedigrees, and Chi-Square Statistics” with my introductory classes. I switch it with the “Teosinte Hypothesis” activity every other semester, or even between groups depending on the level of engagement I see in my students. If they are more engaged, I use the “Mendelian Genetics” activity to help them go deeper into the content; if they are not, I go for the “Teosinte Hypothesis” activity, which is more concise. The “Mendelian Genetics” activity uses an example of natural selection in humans: the inheritance of the sickle cell trait. I love this activity because it walks you through concepts in genetics (e.g., homozygote vs. heterozygote, phenotype vs. genotype) while talking about a real genetic disease and linking it to natural selection. When I use this activity, I follow the same sequence of classes described in the bulleted list above, but instead of watching the Popped Secret film, we watch The Making of the Fittest: Natural Selection in Humans. We do the “Mendelian Genetics” activity up through the section on pedigrees. I don’t do the chi-square section in my introductory course, but you could do it for AP Bio because it uses statistics to analyze the pattern of inheritance.
For introductory courses, I’ve also used “Molecular Genetics of Color Mutations in Rock Pocket Mice” to cover the concept of mutation at a basic level. It is a great hands-on activity to review types of mutations and their potential effects on a protein. It takes me two 50-minute classes to implement.
- During the first class, I ask different students to read the introduction out loud, and I ask clarifying questions about the types of mutations (deletion, insertion, missense, silent, etc.) presented. After that, I split the students into teams of five, assigning Table 1 from the activity to half of the teams to examine, and Table 2 to the other half. Each student must transcribe and translate one sequence, and then share it with the rest of their team members. We then share the results on the board (or virtual board if the class is being conducted online).
- During the second class, students work in pairs for 30 minutes to answer the remaining questions based on previous work and the tables they examined. We then share some answers as a group in the last 15 minutes of the class.
For intermediate-level biology, when I need to address the topic of mutations and pedigrees, I use the activity “Pedigrees and the Inheritance of Lactose Intolerance.” This activity uses a great example students can relate to. Even though almost all my students know someone who is lactose intolerant or are lactose intolerant themselves, they are surprised to see that at least 30% of the class is lactose intolerant and more than 50% have lactose-intolerant parents or siblings. This activity takes two 50-minute sessions to complete as follows:
- During the first class, I give the students a few minutes to read the introduction. We then work together on the first pedigree presented. It’s important during this exercise to ask questions about what each pedigree symbol means so that students are able to distinguish between types of inheritance (autosomal vs. sex-linked), determine if an allele is recessive or dominant, and make predictions about patterns of inheritance. We do a whole group check-in to make sure each student can identify what a good claim about inheritance looks like and to confirm they are not mistaking shaded symbols for “tolerant” and blank symbols for “intolerant.”
- During the second class, I place students in small groups (or breakout rooms for online classes). Each group analyzes pedigrees of the various families found in the activity for 25–30 minutes. When they’re done working, I do a whole-class review by asking one member of each team to share one answer.
After completing this activity, students really comprehend the inheritance of autosomal genes. If you want to continue to cover mutations, you can complete the remainder of the activity, which asks students to identify the mutation in each individual by analyzing DNA sequences.
Finally, for my AP Biology class, I’ve used the activity “Mapping Genes to Traits in Dogs Using SNPs.” I do it in two sessions of 50 minutes each, with some parts assigned as homework.
- Before the first class, I have students watch the lecture “Dog Genomics and Dogs as Model Organisms” as homework. I print and cut the cards that students will use for the second class meeting, with one set per team of 3 or 4 students.
- During the first class, we briefly discuss the lecture that students watched as homework. They individually read the first few pages of the activity and summarize the content in their notebooks. I play some music while they are doing this, which helps them focus on the task. (During each class, a different team gets the chance to select the music.) Then, in pairs, they complete Part 1, which covers an introduction on how gene variants determine dog coat differences and verify their comprehension of the term “SNP.” There is always a group of students who say “awwww” when they see the dog illustrations. I’ve also heard things like “mine is like this one!” or “my grandma’s dog used to look like this!” as they engage with the topic. Later, they complete Part 2, which covers how genome-wide association studies (GWAS) work, as individual homework.
- During the second class, they work in pairs again using the cards I prepared and complete Part 3 of the activity. This part includes graphing and quantitative analysis of the data obtained by analyzing the SNPs. If you want to take your students further, you can use a third session to do Part 4 of the activity, which involves a statistical analysis using chi-square.
Through these activities, students connect and engage with abstract concepts in biology, such as genetics, and make the learning process more meaningful than just using examples of peas and flowers. Whether it is mice, corn, genetic diseases, or dogs, there are always examples that students can relate to in BioInteractive activities.
Cinthya Fernández is a high school science teacher at Tecnológico de Monterrey University, Mexico City Campus. She also facilitates professional development for teachers in multicultural education, STEM, and inclusive teaching. Her lifelong passion for STEM and education has involved her with very different networks, including BioInteractive and FIRST FRC. She also plays flag football and soccer, and loves mystery novels.
Lee Ferguson describes BioInteractive resources that show the intimate and essential connection between Mendelian inheritance and evolution.
Jackie Washington describes how she uses the BioInteractive pedigree analysis activity, in conjunction with the Learning From Patients Holiday Lecture, to teach Mendelian genetics to her college students.