Abstract
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.