The Plasma The Plasma MembraneMembraneThe Plasma The Plasma MembraneMembrane

7.27.2

I. Maintaining Homeostasis

A. ___________- The flexible boundary between the cell and its environment1. A.K.A. Cell Membrane2. Maintains ______ (balance) by letting some things in and keeping others out

Sniff and toss balloon activity

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

I. Maintaining Homeostasis

2. Water moves freely 3. _____ such as calcium and sodium have to enter the cell in other ways4. Selective permeability lab

II. Plasma Membrane Structure

A. ____________ bilayer1. Bilayer = 2 layers2. Phospholipid = 1 Phosphate group

+ 2 fatty acid chains (lipid)3. 2 layers of phospholipids

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!!!

I. Plasma Membrane Structure

4. The _______ group is polar (likes water)

a. Face the outside5. The fatty acids are non-polar (repel water)

b. On the ______ of layer

c. Keeps water soluble molecules from moving in too easily

I. Plasma Membrane Structure

B. Fluid Mosaic Model- 1. The ________ is not rigid2. The phospholipids and _______ are constantly moving around each other

a. Like a tub of water with ping-pong balls floating on the surface

I. Plasma Membrane Structure

C. ____________1. Stabilizes the membrane2. Keeps fatty acid tails from getting tangled3. Not all cholesterol is bad!

I. Plasma Membrane Structure

D. Transport Proteins-1. ________ in the membrane2. Allow movement of substances in when needed3. Allows for the movement of _____ products out of the cell4. Once again, maintains ____________

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?

I. Recap- What is the role of

cholesterol in the membrane?

- How to large water soluble molecules needed by the cell get inside?