1. The Cell Membrane
(Plasma Membrane)

2. The Cell Membrane Surrounds all living cells
Controls how substances can move in and out of the cell
The membranes that surround the nucleus and other organelles are almost identical to the cell membrane
It is semi-permeable meaning it allows only certain substances through it
Protects the cell from the outer environment

3. The Structure of the Cell Membrane
Contain:
Phospholipids
Proteins
Carbohydrates

4. Phospholipids
Cell membrane is made of two layers composed mainly of molecules called phospholipids
Glycerole and Phosphate
-charged 
-hydrophilic + -
Fatty Acids
-uncharged 
-hydrophobic

5. Phospholipids
Arranged in two layers, each has the charged part facing either the watery exterior or interior environment
Uncharged fatty parts are sandwiched between
Cholesterol is spaced throughout each layer to prevent the phospholipids from moving around too much

6. Proteins Transport protein allows substances in and out of the cell
Identifier protein describes the type of cell it is
Marker protein tell if there is an important spot nearby
These proteins are imbedded in the layers

7. Carbohydrate Chains Glycoproteins: proteins with carbohydrates
Glycolipids: phospholipids with carbohydrates
Function as protection

8. Fluid Mosaic Model of a Cell Membrane
The phospholipids, proteins, and cholesterol can move amongst themselves somewhat like particles floating on a thin layer of oil
Fluid refers to the ability of the membrane “peas” to move
Mosaic refers to “little peas” working together

9. Special Properties of the Cell Membrane
Substances can pass into or out of the cell or organelles with help from the protein molecules
Some proteins molecules form a tunnel that helps move substances across the membrane
Proteins regulate the chemical reactions that take place