1. Cell Membrane: Structure and Function

2. The Plasma Membrane • Cell membrane and nuclear membrane are plasma membranes • Semi-permeable • Phospholipid bilayer with proteins • Fluid-mosaic model • http://www.susanahalpine.com/anim/Life/memb.htm

3. Cell Membrane • Phospholipid bilayer Lipid Phospho Layer 1 Layer 2 Two layers = bilayer

4. Why bother with two layers? Water loving (hydrophilic) outside Water fearing (hydrophobic) inside Fears water Loves water Layer 1 Layer 2

5. Membrane Proteins • Channel protein • Carrier protein • Cell recognition protein • Enzymatic protein • Receptor Protein http://en.wikipedia.org/wiki/File:Fluid_Mosaic.svg

6. Transport Proteins1) Channel or 2) Carrier Channel Protein Side View Top down When open allows sugars, salts, and amino acids to pass http://phet.colorado.edu/en/simulation/membrane-channels DOI:10.2210/pdb2jqy/pdb

7. Receives a special molecule Opens the closed gate Extracellular End Intracellular End • Carrier Protein 10.2210/pdb2bg9/pdb

8. Channel vs. Carrier Proteins

9. 3) Cell Recognition Protein What blood type are you? A, B, AB or O? Extracellular DOI:10.2210/pdb2edo/pdb

10. 4) Enzymatic Proteins Angiotensin II Makes a molecule that increases blood pressure

11. 5) Membrane Proteins- Receptor Protein Acetylcholine Receptor Extracellular Intracellular Do you like to move your muscles? 10.2210/pdb2bg9/pdb

12. Summary • Proteins play a large role in the function of cells (therefore our lives) • Different types of protein structures have different functions • Small examples given there are many thousands of proteins in nature • Tutorial/self-check: http://www.bio.davidson.edu/people/macampbell/111/memb-swf/membranes.swf (link on homework page)