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Wrestling with Weight Loss

The Dangers of a Weight-Loss Drug


Susan M. DeSimone
Biology Department
Middlebury College
Annie Prud’homme-Genereux
Continuing Studies and Executive Education
Capilano University


In this interrupted case study, a young wrestler considers purchasing 2,4-dinitrophenol (DNP) online as a means to drop weight quickly. However, a finding that it may have killed someone concerns him. Through progressive disclosure of information, students expand their understanding of membrane permeability and the proton motive force in mitochondria to understand how DNP acts in mitochondria and how it may lead to various physiological effects. Follow-up assignments use knowledge gained in the case to understand mitochondrial thermogenesis in brown fat function and human evolution. The case may be used as a stand-alone exercise in a classroom or be paired with a laboratory investigation using isolated plant mitochondria. It is suitable for an introductory cell biology course for biology majors and non-majors.


  • Know the order and linkage of the biochemical processes involved in ATP synthesis in mitochondria (glycolysis, TCA cycle, electron transport chain, proton pumping, ATP synthase activity)
  • Be able to describe how mitochondria may generate heat to maintain body temperature.
  • Apply concepts underlying mitochondrial function to the mechanism of action of a specific diet pill.
  • Be able to extract data from a graph, and use that data to make inferences about the action of DNP.
  • Relate fundamental principles of mitochondrial function to their own health.


DNP; 2,4–dinitrophenol; mitochondria; mitochondrion; permeability; proton motive force; proton gradient; energy transfer; ATP; uncoupler; substance use

Topical Areas


Educational Level

Undergraduate upper division


PDF, PowerPoint

Type / Methods

Dilemma/Decision, Discussion, Interrupted, Laboratory



Subject Headings

Cell Biology  |   Molecular Biology  |   Biology (General)  |  

Date Posted


Teaching Notes

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Supplemental Materials

The case includes a set of three PowerPoint slides with animations of the diagrams given to students. They are intended to be shown in class between Parts II and III and Parts III and IV of the case.


Answer Key

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Terence Morris
Basic Health Sciences
Excellent! I will use this in next week's tutorial. An imaginative way to convey an often dry subject. Thanks!