1. Fluid Mosaic Model of the Cell Membrane

2. 3 Main Functions of the Cell Membrane
1. Flex - but still maintain shape
2. Regulate the exchange of materials between the cell’s contents and the external environment (homeostasis)  selectively permeable
3. Communicate with other cells

4. Basic Structure of the Cell Membrane: “Phospholipid bilayer with embedded proteins”

5. Phospholipid Bilayer (#1)
Two layers:
1. Phosphate head (#1a)
On the outside
Polar
Attracts water
hydrophillic

6. 2. Lipid Tails (#1b) Inner layer Fatty acids Non-polar Repel water
Hydrophobic
Moveable (unsaturated lipids)
Not as fluid: more saturated lipids

7. Embedded Proteins (Three types)

8. A. Transport Protein (#2)
Regulate movement of molecules through membrane
May have channels to move substances through

9. B. Recognition Proteins (#3)
Serve as attachment sites for ID markers

10. C. Receptor Protein ( #4) Binding sites for attachment of molecules
Activate a cell response

11. Carbohydrate Antennae (#5)
ID marker
Tell what type of cell
Tell whose cell

12. Cholesterol Molecules (#6)
Holds two layers together; provides structure
More cholesterol
Stronger
Less fluid