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Betty Jo Chitester
Assistant Professor
Chemistry Department
Gannon University
Oh, What a Difference a Carbon Can Make! 

Sarah, trapped in the middle of a two-hour lecture on enzyme inhibition, attempts to escape by asking a question. She relates an old story she heard about some teenagers who drank from bottles of antifreeze marked "alcohol." Half of them died, but those who drank a mixture of ethanol and methanol survived. Why? The case uses this example of methanol poisoning to illustrate competitive inhibition of an enzyme (alcohol dehydrogenase) by ethanol.  Data from an enzyme kinetic experiment is presented. First, students identify control, independent, and dependent variables in the experimental design.  Next, students plot the data using the Michaelis-Menten equation; the graphs, both with and without inhibitor present, include the inverse of the reaction velocity on the y-axis and the inverse of the substrate concentration on the x-axis.  Finally, students analyze the graphs and draw conclusions regarding the type of enzyme inhibition, competitive or noncompetitive, and the application of that to the case. Although developed for a second-semester course for Physician's Assistant majors to teach them biochemically relevant structural and functional chemistry, the case could also be used for undergraduate courses in biochemistry and cell biology for science majors.

What’s in Your Water? 

This directed case study uses a fictionalized story about a family that has recently moved to the Washington DC area and is confronted with a situation involving lead contamination of the municipal water supply. Students learn how basic chemical principles apply to human health and safety and, through selected readings, are introduced to sources of lead in drinking water as well as background information on municipal water supply treatment. Students use government sites to find the rules and regulations regarding drinking water and permissible levels of lead. They then research the health effects of lead and other sources of lead exposure in addition to drinking water.  The case includes opportunities for exploring the ethical issues involved in the DC lead contamination incident as well as for getting some practice in applying general chemical principles such as solubility and concentration units. This case would be appropriate for use early on in a fundamental chemistry course after students have been introduced to ionic compounds, atomic structure, ions, and unit conversions.