1. Plasma Membrane Notes

2. CHARACTERISTICS: Maintains homeostasis (balance with environment) Selective permeability – allows some molecules into the cell while keeping others out.

3. Example of selective permeability – screen door keeps something out (bugs, pets, small children) and allows something through (small things)

4. STRUCTURE:

5. Phospholipids: Lipids (fatty acid) with a phosphate group attached. Polar head and non-polar tails Hydrophilic (likes water) head and hydrophobic (afraid of water) tail

6. Tail

8. Hydrophilic and Hydrophobic Hydrophilic: likes water Hydrophobic: fears water - repels water

11. Carrier Proteins Found in plasma membrane (also known as transport proteins) Allows larger substances to move through the plasma membrane.

13. Cholesterol molecule Helps stabilize the phospholipids Prevents the fatty acid chains of the phospholipids from sticking together