1. Plasma Membrane

2. Function of the Plasma Membrane Plasma Membrane is responsible for homeostasis. Homeostasis is the process of maintaining balance in an organism's internal environment. It's a thin, flexible boundary between a cell and its environment that allows nutrients into the cell and allows waste and other products to exit the cell. It is selective permeable which means that some substances can pass through while keeping others out.

3. Structure of the Plasma Membrane Plasma membrane is made up of phospholipid bilayer which has a polar hydrophilic head and 2 nonpolar hydrophobic tails. Hydrophilic means water loving Hydrophobic means water fearing Phospholipid bilayer looks like a sandwich with the hydrophilic head facing outside and the hydrophobic tails facing the inside.

5. Transport proteins- part of the plasma membrane. They span the entire membrane and create tunnels through which substances enter and leave the cell. They move the needed substances or waste materials through the plasma membrane. Fluid mosaic model- refers to a plasma membrane with substances that can move around within the membrane.