1. 2 types of passive transport
3.4 Diffusion and Osmosis
KEY CONCEPT
Materials move across membranes because of concentration differences. This is called PASSIVE TRANSPORT. Passive transport does not require cellular energy.
2 types of passive transport
Diffusion
osmosis

2. The goal is to reach equilibrium
Diffusion
Molecules move from an area of high concentration to an area of low concentration
The goal is to reach equilibrium

3. Molecules diffuse down a concentration gradient.
Diffusion
Diffusion requires NO ENERGY!
Molecules diffuse down a concentration gradient.
(difference in concentration)

4. Osmosis
Osmosis: the diffusion of water Dialysis: the diffusion of solute Solute + Solvent = Solution (dialysis) (water)

5. There are three types of concentration gradients:
Diffusion and Osmosis
There are three types of concentration gradients:
1) isotonic

6. Diffusion and Osmosis
2) hypertonic

7. Diffusion and Osmosis
3) hypotonic

8. Some molecules can only diffuse through transport proteins.
Some molecules cannot easily diffuse across the cell membrane.
Facilitated diffusion is diffusion through transport proteins.