1. Digestion and Membrane Permeability Investigation

2. Membrane Permeability and Dialysis Tubing
Dialysis tubing is a selectively permeable membrane used to separate large molecules from small ones. It is often used in diffusion demonstrations.
How is dialysis tubing a good model for absorption in the small intestine?

3. Your goal: Design an experiment to test the permeability of dialysis tubing

4. Materials Available Tests Available
30cm of dialysis tubing
Beakers
String
Funnels
Graduated cylinders
Water
Milk
Lactase
Coca Cola
Sugar
Corn Starch
Good ol’ observation
Glucose test
Strips or Benedict’s
Starch test
pH Test

5. Tests for glucose Place approx. 1 ml of test solution into a vial
Benedict’s test
Glucose Test strips
Place approx. 1 ml of test solution into a vial
Add 2 ml (10 drops) of Benedicts solution
Heat the vial in a hot water bath for 3 to 5 minutes
Remove vial and let cool. A color change is a positive test for monosaccharides.
Dip the test strip into the solution.
Wait a few minutes then compare the color of the test strip to the bottle.
Only 2 per group!

6. Test for starch Add the solution you would like to test to a beaker
Add a few drops of Iodine to the solution
It will turn dark purple as it complexes with starch.

7. pH test Dip the end of the pH test strip into the solution.
Wait a minute and compare the color of the strip to the container.

8. What your lab report needs to include:
Title
Method and procedure- What exactly are you going to be doing?
Prediction- What do you think will happen?
Hypothesis- What is your explanation for your prediction?
Data- What did you observe?