1. Pre-AP Biology Membrane Structure & Function

2. The Edge of Life
The plasma membrane of a cell is the boundary that separates the living cell from its surroundings.
It is only about 8nm thick—it would take over 8,000 of them to equal the thickness of a piece of paper.
It is essential to maintain the internal environment of the cell.

3. Selective Permeability
The plasma membrane exhibits selective permeability—it allows some substances to pass through more easily than others.
What needs to come into a cell? (oxygen, water, nutrients, ions)
What needs to leave a cell?(carbon dioxide, water, wastes, proteins)

4. Cell membranes are fluid mosaics made of lipids and proteins
The most abundant molecules in cell membranes are phospholipids and proteins. Phospholipids are amphipathic. What does this mean?
Phospholipids make a bilayer around the cell with water inside the cell kept separate from water outside the cell.