1. Diffusion
Particles naturally travel from areas where they are crowded to areas where they are less crowded.
Diffusion is the movement of particles from an area where their concentration is high to an area where their concentration is low.

2. Osmosis All living organisms depend on water
Living cells are surrounded by and filled with fluid that is made up mostly of water
The diffusion of water across a cell membrane is so important to life processes that it has been given a special name – osmosis.

3. *Checkpoint*
What would happen to a grape if you placed in a dish full of pure water?
What would happen to a grape if you placed it in water mixed with a large amount of sugar?
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>

4. Moving Small Particles
Some particles (such as water and oxygen) are small enough to diffuse directly through the cell membrane
Others (such as sugar and amino acids) are too large to squeeze through the membrane and require protein “doorways” in order to enter or leave the cell.

5. Passive Transport
Passive transport is the diffusion of particles through proteins.
These particles move from an area of high concentration to an area of low concentration.
Requires NO ENERGY

6. Active Transport
Active transport is the movement of particles through proteins against the normal direction of diffusion.
Particles are moved from an area of low concentration to an area of high concentration
Requires ATP

7. Moving Large Particles
Endocytosis
Means “within the cell”
Cell membrane surrounds a particle and once the particle is completely surrounded, the vesicle pinches off and enters the cell.

8. Moving Large Particles
Exocytosis
Vesicles inside the cell travel to the cell membrane and fuse with it to release the particles.