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Robin Pals-Rylaarsdam
College of Arts and Sciences
Saint Xavier University
Classic Experiments in Molecular Biology 

All introductory biology textbooks, and many sophomore-level genetics textbooks as well, describe several classic experiments in molecular biology. This interrupted case study takes students through two of these classic experiments, namely, those by Griffith and Avery, McCarty and MacLeod that showed DNA to be the genetic material in Streptococcus pneumoniae, and the experiment by Meselson and Stahl that demonstrated DNA replication to be semiconservative. Engaging students with the experiments in a more exploratory manner can reinforce the nature of scientific discovery and the logic behind these findings. The case, which has been formatted as two separate exercises that can be used independently, was developed for use in introductory biology classes for biology majors. The material is accessible enough to also be useful for non-majors college biology or high school AP biology students.

Closing the Gap: Antiretroviral Therapy for the Developing World

In this problem-based learning/role playing case, students apply their knowledge of the biology of HIV/AIDS and antiretroviral therapy to developing foreign aid policy for the HIV/AIDS crisis in sub-Saharan Africa. The case was created for a non-majors course in human biology taken mostly by juniors or seniors. It has also been used in a microbiology course for pre-nursing students and in an upper-level microbiology course for biology majors.

The Evolution of Creationism: Critically Appraising Intelligent Design

This PBL case on Intelligent Design was written for freshman biology majors at a Christian liberal arts college. Students read about the claims and actions of proponents of Intelligent Design as they work for its inclusion in the high school science curriculum. In the process, students learn about the nature of science and the importance of evolution in the field of biology. More advanced students are given the task of critically evaluating one specific (and much cited) claim made by Intelligent Design supporters that the irreducible complexity of the bacterial flagellum suggests it cannot be the product of evolution.

Tougher Plants: Beating Stress by Protecting Photosynthesis in Genetically Modified Plants

This "clicker case" follows two recent college graduates as they look for scientific answers to explain why the plants on their new tomato farm are not doing well. Working with their agricultural extension agent, they explore the scientific literature and learn how cold, heat, and salt can stress plants. They also learn that plants genetically engineered to produce glycine betaine, a modified amino acid, can withstand the environmental conditions that stress many agricultural plants. In their explorations, the fledgling farmers read graphs from the primary literature and review photosynthetic processes from their introductory biology course. The case consists of a PowerPoint presentation with embedded multiple-choice questions that students answer using clickers.  Developed for a first-year class in biology, it could be used in any lower-level college biology class or potentially an advanced biology class in high school. The case is also accompanied by an optional PowerPoint presentation (see "Supplemental Materials" tab above).