1. Cell Membrane Daniel Mawhirter 2 Green

2. History 1855 - C. Naegeli and C. Cramer describe cell membrane as barrier essential to explain osmosis in plant cells

3. History (Continued) 1972 – The fluid mosaic model was created by S. J. Singer and Garth Nicolson, and stated that cell membranes can be considered as a two-dimensional liquid where all lipid and protein molecules diffuse freely

4. Structure

5. Structure (Continued) Primarily lipids and proteins Unsaturated/Saturated changes rigidity Polar, usually rejects ions, hormones, ion channels Proteins stretch through, integral proteins Cellular communication/recognition

6. Location In an animal cell, outermost layer In a plant cell, just inside cell wall Present in both

7. Function The lipid bilayer provides rigidity, maintaining the shape of the cell Materials that can be dissolved in water pass through the membrane via osmosis Other materials rely on ion channels to move through

8. Interactions Works with the cytoskeleton, structure Ribosomes produce proteins that are then inserted into a lipid bilayer of their own by the endoplasmic reticulum and transported to the cell membrane by a vesicle, where both are absorbed into the cell membrane

9. Efficiency and Effectiveness Seperates the cytoplasm from the extracellular environment Allows materials to be transported across it If the cell membrane were not there, it wouldn’t make sense to call it a cell, more of a soup that flows around mixing with its surroundings and spreading out.

10. Sources http://www.usoe.k12.ut.us/CURR/science/sciber00/7th/cells/sciber/membrane.htm June 15, 2000 http://www.cellsalive.com/cells/cell_model.htm, 2006 http://en.wikipedia.org/wiki/Cell_membrane, 14 November 2009 http://www.whatislife.com/education/fact/history_table.html, November 8, 2009