Diffusion: Molecules on the Move
Dialysis tubing is an excellent way to simulate the cell membrane’s selective permeability. In this experiment, sealed dialysis tubing containing a test solution of albumin, glucose, sodium chloride, and starch is placed in a cup of distilled water. After 30 to 45 minutes, the tubing is removed from the cup and its contents, and the cup of water is tested to determine whether the components have diffused across the membrane.
Conclusion
In this experiment, students should see that glucose is the only molecule able to move across the cell membrane. This is primarily due to the size of the molecules, as both albumin and starch are larger than glucose. After performing this experiment, your students should have a good start to understanding of the movement of molecules as it relates to cell membranes’ selective permeability.
SHOP THE KIT
