Osmotic properties of cells: a computer laboratory

A computer laboratory has been designed to teach the osmotic properties of cells. One program, CELL.BA, is for the teacher to enter values for the volume of cell water and osmotically inactive material, the concentration of impermeant solute in the cell, and the permeability of the plasma membrane to water and a nonelectrolyte. When the program is protected, students use it as a cell with unknown osmotic properties. They run experiments on the computer with different concentrations of impermeant or permeant solutes or combinations of the two. Changes in cell volume or solute concentration are collected as data and analyzed with the program, PERMEABILITY LAB.BA. This program provides a parameter list, and students try to fit the data that are graphed on the screen by choosing values for the unknown cell parameters and generating model curves. Programs are written for the Macintosh computer.