1. The Plasma Membrane 7.2

2. I. Maintaining Homeostasis A. ___________- The flexible boundary between the cell and its environment 1. A.K.A. Cell Membrane 2. Maintains ______ (balance) by letting some things in and keeping others out

3. Sniff and toss balloon activity

4. I. Maintaining Homeostasis B. ______ Permeability- Feature of the cell membrane that allows some molecules in to the cell while keeping others out. 1. Ex: Strainer, screen, filter

5. I. Maintaining Homeostasis 2. Water moves freely 3. _____ such as calcium and sodium have to enter the cell in other ways 4. Selective permeability lab

6. II. Plasma Membrane Structure A.____________ bilayer 1. Bilayer = 2 layers 2. Phospholipid = 1 Phosphate group + 2 fatty acid chains (lipid) 3. 2 layers of phospholipids

7. Note: _______ are important because they do not dissolve in water. What would happen if the membrane was made of water soluble substances??? A. It would break down and the cell would die!!!

8. I. Plasma Membrane Structure 4. The _______ group is polar (likes water) a. Face the outside 5. The fatty acids are non- polar (repel water) b. On the ______ of layer c. Keeps water soluble molecules from moving in too easily

9. I. Plasma Membrane Structure B. Fluid Mosaic Model- 1. The ________ is not rigid 2. The phospholipids and _______ are constantly moving around each other a. Like a tub of water with ping-pong balls floating on the surface

10. I. Plasma Membrane Structure C. ____________ 1. Stabilizes the membrane 2. Keeps fatty acid tails from getting tangled 3. Not all cholesterol is bad!

11. I. Plasma Membrane Structure D. Transport Proteins- 1. ________ in the membrane 2. Allow movement of substances in when needed 3. Allows for the movement of _____ products out of the cell 4. Once again, maintains ____________

12. I. Recap -Why is the plasma membrane important? -What property allows the membrane to let some things in and keep others out? -What 2 main parts make up the phospholipid bilayer?

13. I. Recap -What is the role of cholesterol in the membrane? -How to large water soluble molecules needed by the cell get inside?