Three Cases from the Membrane Files

By Eric Ribbens

Abstract

This PowerPoint-driven case study presents three different stories, each of which explores an aspect of membranes. The first (The Exploding Fish) covers diffusion, specifically addressing the question of why animal cells explode in freshwater but fish do not, and differences between saltwater and freshwater fish. The second case (The Pleasurable Poison) is designed to show that alcohol can slip across membranes and also highlights some of the problems of ingesting this toxin. The third case (The Dangerous Diet) explores a weight-loss drug, DNP, and how it operates in mitochondrial membranes. The first of these case studies also includes a number of "clicker" questions. These cases were originally designed for a semester-long, introductory biology course for non-majors, and instructors can choose to use one or all of the cases to suit their course.

Download Case

Date Posted

07/30/2015

Overview

Objectives

Explain the concept of diffusion, both generally and across a semi-permeable membrane.
Describe at a basic conceptual level how the mitochondria generate ATP.
Apply these principles to the case scenarios to indicate why water balance management is important, why drinking alcohol has such devastating effects on our bodies, and how DNP can disrupt mitochondrial activity.

Keywords

Membranes; mitochondria; semi-permeable; kidneys; alcohol; dinotrophenol; DNP; ATP; diffusion; osmosis

Subject Headings

Biology (General)

Cell Biology

EDUCATIONAL LEVEL

High school, Undergraduate upper division

FORMAT

PDF, PowerPoint

TOPICAL AREAS

N/A

LANGUAGE

English

TYPE/METHODS

Clicker, Interrupted

Teaching Notes & Answer Key

Teaching Notes

Case teaching notes are protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, purchase a subscription here.

Teaching notes are intended to help teachers select and adopt a case. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources.

Download Notes

Answer Key

Answer Keys are protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, purchase a subscription here.

Note: There is no separate answer key for this case.

Materials & Media

Supplemental Materials

Optional PowerPoint presentation that can be used as preparatory material.

Optional Pre-class Presentation

Videos

Diffusion Across Membranes
This four-second animation discusses two types of transport across cell membranes: active and passive transport. Running time: 0.04 min. Produced by HHMI BioInteractive.