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Paint ...it was just paint, not treasure. I can't believe the paint has lasted so long down in these tombs. It reminds me of the bacteria from our earlier tour. The walls of the tomb have acted as a barrier; it keeps air and moisture from moving in and out freely to preserve the paint. As we head back to camp for the night, I can't help but think about how the insect netting that surrounds our sleeping bags and the walls of the tomb are like a cell membrane. The cell membrane is a gate keeper, and just like the netting, it controls the movement of insects in and out of the sleeping area. The walls of the tomb control the movement of air and moisture just as the cell membrane controls what materials enter and leave the cell. The Cell: Cellular TransportationEvery living cell has a cell membrane. Even if the cell has a cell wall (like plant cells) on the outside, it still has a cell membrane inside. As you learned earlier, many individual organelles also have similar membranes that surround them. Examine the electron microscope images of a cell membrane below. This one shows two cell membranes next to each other. The intercellular space is the space between the two membranes. Notice that the actual membrane is a double layered structure. Click on the picture of the cell membrane to learn more!
Sometimes transport of materials is easy and requires no energy or effort on the part of the cell. However, at other times, passage of materials across the membrane does take work or energy on the part of the cell. Check out the following vocabulary words. The words and definitions should help explain materials transportation and the cell membrane. Please add these to your Travel Log. You will see them again! Click on each word to see the definition. 
Now you have a basic understanding of the terms related to movement of substances in and out of a cell. Take a few minutes to exit the course and head out to a great resource to investigate active and passive transport.
Northland College Biology Program's: Membrane Transport 
Putting Your Knowledge into Action Grab your lab coat and your travel log. Time to conduct an experiment! You are about to see cell transportation at work. Access the lab instructions from the link below and get busy setting up.
If you have begun the lab activity above click on the Travel Log tab to finish this tour activity!
Electron microscope image of two cell membranes from http://cellbio.utmb.edu/cellbio/membrane.htm, cell membrane diagram from http://en.wikipedia.org/wiki/Cell_membrane, tour guide Niles, globe © clipart.com 2006, notebook © Paul Anderson 2006
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Unless otherwise noted, © 2006 - 2008 FLVS |
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Think of the cell membrane as the gate keeper; it manages substances coming into and out of the cell. Cells must obtain certain nutrients and chemicals to function properly and at the same time get rid of wastes, so it won't die of toxic build up. 
