Cell Membranes and Bubbles

I was happily reading through the Facebook feed of the AP Biology teacher group and saw a post from a teacher who had just done a bubble lab to teach properties of cell membranes. It looked like fun and I was about to embark on cell membranes. The lab is from Jeremy Conn of Clear Biology.  You can download the lab from his site here. I just used his resource without any editing--which is handy since I'm having a hard time keeping up with everything to do. I made some bubble solution on a Thursday, and we did the lab this past Monday.

I think sometimes I forget that even though I teach Seniors, they are still kids.  (Actually, we should all be kids at heart.) The students loved this lab and had so much fun playing with bubbles.  And in the end I felt like they significantly improved their understanding of cell membranes and the fluid mosaic model.

As they progressed through the activities, they got more excited. My favorite was the loop of thread that opened to a circle and then could move around the bubble frame like a transmembrane protein.

As they were cleaning up, I heard conversations about how they should do this bubble lab with their fourth grade buddies. (One advantage of being in a K-12 school.) Love it!

Membrane Models

Today in my Living Environment class, we started talking about cell membranes and the idea of them being selectively permeable.  Since we can't actually see the structure of the lipid bilayer, we built it.  We talked about the hydrophilic heads and the two hydrophobic tails of each phospholipid. We also talked about the proteins embedded in the bilayer that allow molecules through that couldn't otherwise pass through the bilayer.

Each student had a slightly different vision of their membrane. We had some very spread out phospholipids and some very tightly packed ones. Some were more fluid than others. The idea came from a pin on Pinterest.  It was just a pin of a picture, so I'm not sure who to attribute it to.  I typed up a version of the activity for my students based on the picture.  I just made it on a half page, so it would fit easily in their notebooks.  

This bilayer got squeezed into one layer. Oops!

We capped the class off with our diffusion and osmosis lab, so they could see the actual movement of molecules across a membrane.