Exercise 6.4 - Computer Simulation of Membrane Function

LEVEL I

Materials

• CELLM program found in Appendix D
• Computer capable of running BASIC

Procedure

1. Turn on the computer, boot with an appropriate DOS, and load the program CELLM.

   The program asks you to make decisions about the amount of water, sugar, ions and wastes that are within an E. Coli cell. Changes in the cell due to osmosis and diffusion take place automatically. Energy is required for the movement of wastes and for other functions (such as preparation for reproduction). As you utilize the sugar for energy, wastes will build automatically. To dispose of waste requires 4 molecules of sugar.

   From the time you begin the program, the cell will burn sugar for energy. Diffusion and osmotic potentials go into effect. If you successfully manipulate the parameters, the cell will divide. Otherwise, your cell dies.

2. Your initial concentrations of materials are as follows:

   Water	67% or 6700 molecules
   Sugar	30 molecules
   Sodium	0 molecules
   Potassium	53 molecules
   Waste	0

3. Your cell is then placed into a solution containing:

   Water	87% or 8700 molecules
   Sugar	10% or 1000 molecules
   Sodium	trace
   Potassium	trace
   Waste	0

4. You must adjust the five parameters of the cell, while maintaining viability. Your safe concentrations are:

   Water	6000-8000 molecules
   Sugar	10-35 molecules
   Sodium	0-13 molecules
   Potassium	40-53 molecules
   Waste	0-10 molecules

5. While you play the role of a membrane, attempt to understand the relationship of the various components to each other.

6. Submit a single page report on the game, detailing the components, and how they interact to make the cell divide.

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