A compelling reason to learn something can make all the difference in students’ motivation to learn it.  Motivation, in turn, is one of the key attitudes that drives learning.  This story presents students with a compelling puzzle of a fatherless snake.  The puzzle motivates students to learn about meiosis and mitosis, since the only way to explain the origin of the fatherless baby is by mastering details of meiosis.  During the process, students work through the major steps in meiosis, compare and contrast mitosis and meiosis, and apply their understanding to predict how meiosis “went wrong” to produce an unusual offspring that did not originate through union of an egg and a sperm.  This story can be adapted for introductory or advanced students and can be scaled from a brief introduction in a single lecture to a series of active learning exercises that could take two or more lecture periods.

Introductory genetics laboratory published as GSA Learning Resource

A young boy wonders why his twin sister can roll his tongue, but he cannot. Case centers on meiosis.

In Developmental Biology classes, students are challenged with understanding how differential gene expression guides embryonic development. It can be difficult for students to realize that genes need to be turned on or off at the right time and place in order for development to proceed normally. In this lab, students working in groups perform experiments with live embryos and visualize differential gene expression allowing them to become invested in their experiment and curious about the results. This lab also addresses the benefits of Xenopus laevis as a model organism and allows students to observe the changes Xenopus embryos undergo during early embryonic stages. After the students have chosen and fixed two stages of Xenopus embryos, they perform an in situ hybridization on the embryos to visualize gene expression at two different developmental stages. They then compare their results with those from other lab groups who analyzed their embryos for different genes. The students self-reported that they better understood the concept of differential gene expression during vertebrate development and enjoyed doing this series of lab experiments working with live materials.

Some concepts in genetics, such as genetic screens, are complex for students to visualize in a classroom and can be cumbersome to undertake in the laboratory. Typically, very large populations are needed, which can be addressed by using micro-organisms. However, students can struggle with phenotyping microbes. For macroscopic organisms, the number of offspring produced, and the generation time can be challenging. I developed this lesson as a small-scale genetic screen of Fast Plants^®. These plants are amenable to teaching labs as they have simple growth requirements, a short generation time, and produce numerous seeds that can be stored for years. Seeds used for this screen are purchased pre-treated with a DNA damaging agent, removing the need for in-house use of mutagens. Also, students can screen the phenotypes without specialized equipment. The initial lesson begins with an examination of the first generation of plants. Later their offspring are screened for altered phenotypes. Students responded well to having full-grown plants available on the first day of the lab project. This lesson fostered student collaboration, as they worked with class datasets. Differences in growth due to mutagenesis treatment in the first generation were clear to students who had not worked with plants before. Identifying plants with altered phenotypes in the next generation was more of a challenge. This lesson incorporates key concepts such as somatic and germline mutations, the impact of such mutations on phenotype, and the inheritance of mutation alleles, and provides a hands-on way to illustrate these concepts.

Primary Image: Fast Plant^® phenotype differences observed in the M2 generation. This pot contains three full-sibling M2 seedlings from a single M1 parent plant. The seed of their parent plant received 50 Krads of radiation. Plants 1 and 2 are of standard height, while plant 3 is greatly elongated. Image by AL Klocko.

Students require a deep understanding of the central dogma before they can understand complex topics such as evolution and biochemical disorders. However, getting undergraduate biology students to apply higher-order thinking skills to the central dogma is a challenge. Students remember and regurgitate the molecular details of transcription and translation but if asked to apply these details, such as how a DNA mutation might affect phenotype, it becomes clear that most students do not deeply understand the central dogma. This lesson is a five-week series of laboratory activities designed to help students transition from applying lower order thinking skills to the central dogma to applying higher-order thinking skills. Over five weeks, students explore the phenotype of Arabidopsis asymmetric leaves 1 (as1) and as2 mutants. Students isolate DNA from wild-type and mutant plants and determine the sequence of the AS1 and AS2 alleles. Students use the DNA sequence data to determine the mutant protein amino acid sequences. They submit the mutant and wild-type protein sequences to a free online server and obtain three-dimensional (3-D) models of the wild-type and mutant proteins. They use free software to analyze and compare the 3-D models to determine the structural differences between the wild-type and mutant proteins. These computer-generated models can be 3-D printed allowing students to better visualize the protein structure. The overall goal is to use student-centered laboratory activities to demonstrate the relationship between DNA sequence, protein structure/function, and phenotype.

The process of cell specialization is critical to the formation and function of tissues in animals and plants. Although gene expression, including the regulation of transcription, is taught in most introductory cell biology courses, the relationship between differential gene expression and the formation of specialized cell types is challenging to understand for even upper-level life science students. In order to decrease this learning gap, I have developed a suite of in-class problem-solving activities and a lab experiment on Axolotl embryos that support student learning and integration of content related to differential gene expression and cell specialization. Although axolotls are best known as a model system for tissue regeneration, recent advances in genomic and molecular tools has increased their application as a model for studying gene expression during embryonic development as well. I tested the activities in an upper-level undergraduate course and found an increase in student understanding of the importance of differential gene expression during cell specialization processes, and the techniques used to study these processes, particularly Real Time quantitative PCR (RTqPCR). Teachers can examine student understanding of techniques and concepts using in-class assignments, exam questions, homework assignments and laboratory notebook assignments. Importantly, by analyzing a specific gene associated with a specialized cell type during different axolotl embryonic stages, students connect and integrate molecular, cellular and organismal level concepts of differential gene expression and cell specialization. This engagement deepens their understanding of the gene expression processes involved in cell specialization and of the role of model systems in biological research.

Although genetics is an invaluable part of the undergraduate biology curriculum, it can be intimidating to students as well as instructors: Students must reduce their reliance on memorization and dive deep into quantitative analysis, and instructors must make a long, rich history of genetics experiments clear, coherent, and relevant for students. Our Lesson addresses these challenges by having students map an unknown mutation to its gene using a modern suite of genetic tools. Students receive a Drosophila melanogaster strain with a mutation that causes the normally flat wing to bend at distinct sites along its length. Although we recently mapped this mutation to its gene, here we have renamed it "crumpled wing" (cw), an example of a pseudonym that you could use in the classroom. Like many standard "fly labs" that are taught at undergraduate institutions, this Lesson reinforces classic genetics concepts: students selectively mate fly strains to determine mode of inheritance, test Mendel's Laws, and three-point map an unknown mutation relative to known markers. But here, we expand on this tradition to simulate a more modern primary research experience: we greatly increase mapping resolution with molecularly-defined transgene insertions, deletions, and duplications; then cross-examine our data with key bioinformatic resources to identify a short-list of candidate cw genes. After extensive data interpretation and integration, students have been able to map cw to a single gene. This Lesson has a flexible design to accommodate a wide range of course structures, staffing, budgets, facilities, and student experience levels.

This lesson provides three activities to engage non-science major students in a discussion about sex, gender, gender identity, and sex determination. Students prepare for the lesson by reading a short article titled Sex and gender: What is the difference? and responding with research topics that would be most appropriate for one term over the other (sex vs. gender). This forms the basis of the first activity in which students brainstorm what it means to be female or male, and then identify whether each idea is related to a sex or gender characteristic, followed by a whole class discussion. The second activity is a clicker question with four published journal article titles, and students identify which is the least appropriate use of the term gender. The final activity involves a case study of María José Martínez-Patiño who failed a sex test in 1985 and was denied the right to compete as a female in the World University Games. In the case study, students grapple with the physiology of androgen insensitivity and what ultimately determines a persons' sex and gender identity. Non-science major students find these activities accessible and engaging, and each activity serves as a formative assessment for both the teacher and student. Summative assessments evaluate the students' level of confidence related to each of the three learning outcomes, and their understanding of terminology, context, and examples of sex and gender.

Mutations in genes can lead to a variety of phenotypes, including various human diseases. Students often understand that a particular mutation in a single gene causes a disease phenotype, but it is more challenging to illustrate complex genetic concepts such as that similar mutations in the same gene cause very different phenotypes or that mutations in different genes cause similar phenotypes. We originally designed this lesson to build off of the CourseSource lesson “A clicker-based case study that untangles student thinking about the processes in the central dogma,” but it can also stand alone. In our lesson, students read or listen to a real-life case study featuring a patient who doggedly pursues the underlying genetic cause of her own disease—muscular dystrophy—and stumbles upon a similar mutation in the same gene that gives an athlete the seemingly opposite phenotype: pronounced muscles. The lesson also leads the students to overlay their understanding of the central dogma and mutation on protein function and disease, compares muscular dystrophy to the disease progeria, and concludes with an ethical challenge. We tested the lesson as both an independent homework assignment, as well as a small group in-class worksheet and both formats were successful.

Primary Image: Line drawing of a space filling diagram of the LMNA protein illustrating mutations that lead to progeria.

Historically, undergraduate genetics courses have disproportionately focused on the impact of genes on phenotypes, rather than multifactorial concepts which consider how a combination of genes, the environment, and gene-by-environment interactions impacts traits. Updating the curriculum to include multifactorial concepts is important to align course materials to current understanding of genetics, and potentially reduce deterministic thinking, which is the belief that traits are solely controlled by genes. Currently there are few resources to help undergraduate biology instructors incorporate multifactorial concepts into their genetics courses, so we designed this lesson that centers on familiar, real-world examples. During this lesson, students learn how to distinguish between genetic and environmental sources of variation, and examine and interpret examples of how phenotypic variation can result from a combination of gene and environmental variation and interactions. This lesson, which is designed for both in-person and online classrooms, engages students in small group and large group discussion, figure interpretation, and provides questions that can be used for both formative and summative assessments. Results from assessment questions suggest that students found working through models depicting the interactions between genotypes and environments beneficial for their understanding of these complex topics.

Primary Image: Mendel’s laws of alternative inheritance of peas. A photo taken by W.F.R. Weldon of variation in color and texture of peas. Reprinted with permission from Biometrika (Weldon WFR. 1902. Mendel’s laws of alternative inheritance in peas).

Constructing a robust understanding of homologous chromosomes, sex chromosomes, and the particulate nature of genes is a notoriously difficult task for undergraduate biology students. In this lesson, students expand their knowledge of human chromosome pairs by closely examining autosomes, sex chromosomes, and the non-homologous elements of the human X and Y sex chromosomes. In this four- part guided activity, students will learn about the structure and function of human autosomal and sex chromosomes, view and interpret gene maps, and gain familiarity with basic bioinformatics resources and data through use of the National Center for Biotechnology Information (NCBI) website. (Student access to computers with Internet connectivity is required for the completion of all Investigations within this lesson.) By viewing chromosomes and gene maps, students will be able to contrast expectations for homologous autosomal chromosome pairs and sex chromosome pairs, as well as gain a deeper understanding of the genetic basis for human chromosomal sex determination. In the last part of this lesson, students can also begin to understand how genetic mutations can lead to sex-reversal. The lesson, as presented, is intended for an introductory biology course for majors, but could be modified for other audiences. In addition, each exercise (“Investigation”) within the lesson can be used independently of the others if an instructor wishes to focus on only a subset of the learning objectives and provide the necessary context.  Options to extend the lesson related to interpreting phylogenies, and contrasting definitions of sex and gender are also provided.

The biology classroom is not separate from the greater context of society; social issues can and should be presented in connection with the content. Here we present an example of antiracist teaching using the molecular/cellular biology of cancer in an introductory biology course as a topic through which to address historic racial disparities. Through this lesson, students analyzed biological science through the lens of social justice, specifically looking at disparities of cancer incidence with ties to health outcomes and environmental racism. The synchronous activity begins with personal tie-ins to the broader subject of cancer and then dives into the molecular regulation involved in creating cancerous phenotypes. Cancer biology is explored using an active-learning style based in process-oriented guided inquiry learning (POGIL) tactics. Multiple levels of assessments pushed students to grapple with data about racial health disparities and make explicit connections between these data and molecular mechanisms of cancer formation. This paper provides activity worksheets, an activity timeline, an example of assessment items, and teacher preparation for other instructors who want to emulate this lesson either directly or as an example of adjusting other science topics towards this lens. For those teaching in different topics, we offer advice and examples to help instructors to include social justice lenses into their science teaching.

Primary image: Malignant History. Artwork by Heidi-Marie Wiggins and Jeannette Takashima.

A strong understanding of distinct gene components and the ability to retrieve relevant information from gene databases are necessary to answer a diverse set of biological questions. However, often there is a considerable gap between students’ theoretical understanding of gene structure and applying that knowledge to design laboratory experiments. In order to bridge that gap, our lesson focuses on how to take advantage of readily available gene databases, after providing students with a strong foundation in the central dogma and gene structure. Our instructor-led group activity aids students in navigating the gene databases on their own, which enables them to design experiments and predict their outcomes. While our class focuses on cardiomyocyte differentiation, classes with a different focus can easily adapt our lesson, which can be conducted within a single class period. Our lesson elicits high engagement and learning outcomes from students, who gain a deeper understanding of the central dogma and apply that knowledge to studying gene functions.

Primary Image: Gene structure at various levels of expression and retrieval of corresponding biological information from gene databases. This image contains a screenshot from the NCBI Database, which is an open source: National Center for Biotechnology Information. 2021. SOX2 SRY-box transcription factor 2.

To facilitate understanding of the fundamental genetic concept of the genotype-phenotype relationship in our introductory biology students, we designed an engaging multi-week series of related lessons about canine genetics in which students explore and answer the question, "How does the information encoded in DNA lead to physical traits in an organism?" Dogs are an excellent model organism for students since the genetic basis for complex morphological traits of various breeds is an active area of scientific research and dog DNA is easily accessible. Additionally, examination of students' pets offers a relatable, real-world, connection for students. Of the more than 19,000 genes that control canine genetics, simple genetic mutations in three genes are largely responsible for the coat variations of dogs –specifically, the genes that control hair length, curl, and the presence/absence of furnishings. In our lessons, students collect DNA samples from dogs, isolate and amplify targeted sections of DNA through polymerase chain reactions (PCR), and then sequence and analyze DNA for insertions and single nucleotide polymorphism (SNP) mutations. Utilizing gel electrophoresis and bioinformatics tools, students connect how the physical manifestation of traits is rooted in genetic sequences. Students also participate in discussions of scientific literature, group collaboration to construct a final poster, and presentation of their findings during a mock scientific poster conference. Through this module students engage in progressive exploration of genetic and molecular techniques that reveal how simple variations in a few DNA sequences in combination lead to a broad diversity of coat quality in domestic dog breeds.

Primary image. Genetic Analysis of Canine Coat Morphologies. Three dogs with differing coat morphologies analyzed by students (A, B, C), an agarose gel post-electrophoresis (D), and a chromatogram of a DNA sequence highlighting a relevant mutation (E). This collage contains original images taken by authors and course participants.

Modern molecular biology is a data- and computationally-intensive field with few instructional resources for introducing undergraduate students to the requisite skills and techniques for analyzing large data sets. This Lesson helps students: (i) build an understanding of the role of signal transduction in the control of gene expression; (ii) improve written scientific communication skills through engagement in literature searches, data analysis, and writing reports; and (iii) develop an awareness of the procedures and protocols for analyzing and making inferences from high-content quantitative molecular biology data. The Lesson is most suited to upper level biology courses because it requires foundational knowledge on cellular organization, protein structure and function, and the tenets of information flow from DNA to proteins. The first step lays the foundation for understanding cell signaling, which can be accomplished through assigned readings and presentations. In subsequent active learning sessions, data analysis is integrated with exercises that provide insight into the structure of scientific papers. The Lesson emphasizes the role of quantitative methods in research and helps students gain experience with functional genomics databases and data analysis, which are important skills for molecular biologists. Assessment is conducted through mini-reports designed to gauge students' perceptions of the purpose of each step, their awareness of the possible limitations of the methods utilized, and the ability to identify opportunities for further investigation. Summative assessment is conducted through a final report. The modules are suitable for complementing wet-laboratory experiments and can be adapted for different courses that use molecular biology data.

In this module, students will be investigating a louse gene with an unknown function to determine if it might be important in the evolution of the louse ecomorphs.