1. Section 7-3 Cell Boundaries

2. Plasma Membrane or Cell Membrane The boundary between the cell and its environment. Controls what enters and leaves the cell Helps the cell maintain homeostasis Selectively permeable – a process by which the plasma membrane allows some molecules into the cell while keeping others out.

3. Plasma Membrane Lipid Bilayer – two layers of lipids.

4. Plasma Membrane Fluid Mosaic Model – flexible Cholesterol is found in the plasma membrane and helps to stabilize the plasma membrane. Prevents the fatty acid chains from sticking together.

5. Transport Proteins Allow needed substances or waste materials to move through the plasma membrane.  Regulates which molecules enter and which molecules leave a cell.