-Regulates what enters and leaves a cell
-Selectively Permeable- cell membrane controls what enters and exits the cell.
-Composed of lipids, proteins, and carbohydrates
-Phospholipid bilayer- hydrophobic tails and hydrophilic heads
-Integral Proteins- imbedded in bilayer
-Peripheral Proteins- sit on top of the bilayer
-Transport Proteins- allow cell to be selectively permeable
-Carbohydrates on outer surface of membrane act as signals for other cells, chemical messages, or viruses to attach.
-Fluid Mosaic Model- constant change and fluid movement of lipids and proteins in cell membrane
ex. bouncer at a night club, parents because they have a say about who you can date, border control, hockey goalie, etc.