Module Instructions: The Cell Membrane

Lecture: The Cell Membrane

Watch the lecture. Read the chapter and complete the study guide in preparation for Exam 2.

Lab: Diffusion and the Cell Membrane

You must provide photographic evidence of your experimental set up with a notecard and your name in the photo. Merge this photo with your lab and submit as a single pdf. Complete the lab and submit in Canvas by the due date in the calendar. Gather your materials and get started.

Experiment 1: Osmosis across a semi-permeable membrane

Items you will not likely have around the house

  • 4 - 15cm strips of dialysis tubing

    • Pre-soaked in water for 10 minutes.

    • I know you can purchase dialysis tubing on Amazon. 

  • Funnel

  • Kitchen Scale (to measure mass)

Items you likely will have around the house

  • 4 cups

  • Sugar

  • Measuring cup

  • Metric ruler (or be able to convert to inches to cm)

  • Small cooking pot

  • 3- clean containers (bowls)

  • Rubber bands

  • Scissors’

Once you have your supplies, the rest of the lab is pretty straightforward. The one thing to remember is that the water will be passing over the dialysis tubing, but not the sugar. To use Beaker B as an example, the “cell” will have a 1% sugar solution, which is 1% sugar to 99% water. The solution it is sitting in will be 50% sugar solution containing 50% water. There is a higher concentration of water inside the cell than out of the cell. Therefore, we would expect more water to flow out of the cell from a higher concentration to a lower concentration. In this case, we would expect the cell to shrink, becoming hypertonic.

 

Be sure to take a photograph of your experimental set up and attach it to your lab. It should look something like this:

 

Experiment 2: Why are cell so small?

In this experiment, you will try to address the question from a geometric perspective. If you are having issues creating the boxes, here is a quick video that will show you the process. It is a little tricky, but once you get it, it is pretty fun. Be sure to make all three boxes. Again, you will need to document your boxes and include the photo in your lab submission.

Quiz: The Cell Membrane

Once you finish your lecture and lab, complete your quiz by the deadline in the class calendar.