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Agony and Ecstasy: Cell Membrane Structure and Function


Norris Armstrong
Biology Department
University of Georgia


This “clicker case” follows Susan, an intern at a local hospital, who has admitted a patient she discovers has used the drug Ecstasy. The girl becomes delirious, and Susan begins to suspect that she may be suffering from water intoxication. The case is designed for an introductory biology course for either science or non-science majors, though it could be adapted for upper level courses. It uses an example of water intoxication to introduce membrane structure and function, osmosis, and electrolyte balance in the body. The case itself is a PowerPoint presentation (~800KB) shown in class that is punctuated by multiple-choice questions students answer using clickers. It could be adapted for use without these technologies.


  • Understand what diffusion is and the physical mechanism that causes it.
  • Understand which types of molecules can (hydrophobic) and can’t (hydrophilic) cross membranes very easily and the reasons for these differences.
  • Be able to explain how water moves across a membrane (directionality) in response to different solute concentrations inside and outside the cell.
  • Understand the dangers of insufficient and excessive hydration and their effects on living cells and tissues.


Diffusion; membrane transport; osmosis; water intoxication; hydrophilic; hydrophobic; hyponatremia; Ecstasy

Topical Areas


Educational Level

High school, Undergraduate lower division, Undergraduate upper division


PDF, PowerPoint

Type / Methods

Clicker, Interrupted



Subject Headings

Biology (General)  |   Cell Biology  |   Medicine (General)  |  

Date Posted


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Erin Poppert
Apopka High School
Apopka, FL
My students LOVE this case study! I like the original animation for how the MDMA works, but this one is put together pretty well. I find that my students may not get all of the vocabulary, but whenever I reference this case study they can figure out what I am talking about and relate back to cell transport and how it works. FYI, I teach this to my regular biology students, so the relevance this has to them is high and makes talking about the cell much more interesting and real to them.

Roya Nabi
Eastern Regional HS
Voorhees, NJ
I used this activity in my Advanced Placement biology class. It was an excellent way to tie up the Cell Membrane/Homeostasis chapter. My seniors had no problems answering the clicker questions of the post assessment questions. Most were able to complete the entire activity with three or less incorrect. They absolutely loved the Mouse Party website; that is a great opener. I may try and tweak this activity for my honors biology students.