Procedures: Make a "Cell" The directions below are for making a "cell" with dialysis tubing. If you are using plastic bags. follow the directions your teacher provides. 1. Take a 20 cm length of dialysis tubing and soak it in warm tap water for a few minutes. You should then be able to pull the ends apart gently, forming it into a tube. Rubbing the ends of the tubing between your fingers under water is sometimes helpful when attempting to open the tube.

2. Seal one end of the tube by folding the end over and tying it closed with a piece of string or dental floss. The goal is to make that end completely leak-proof.

3. Pour glucose solution into the tube until it is about 1/4 full. Next, add enough starch solution to fill the tube about halfway. You can use a funnel to make this easier.

4. Tie off the top of the tube in the same way you tied off the bottom. The tube should not leak from either end. Gently mix the contents of the tube by turning it upside down and back again. Check for leaks.

5. Rinse off the "cell" you've just made by holding it under running water.

6. Place the "cell" in a beaker and add water until the “cell" is just covered.

7. Add Starch Indicator Solution (containing iodine) to the water in the beaker. Add enough to make the water an amber color.

8. Label the "Initial State" part of the diagram found on page 4. Indicate the contents and color of the beaker and cell.

9. Based on your knowledge of diffusion, predict what will happen to the substances inside and outside of the "cell." Record your prediction here: