1. Coulter

2. Diffusion  The cell membrane is selectively permeable, which means that some substances can pass through the membrane while others cannot.  Diffusion- is the process by which molecules move from an area of higher concentration to an area of lower concentration.  Concentration- is the amount of a substance in a given volume.

3. What causes diffusion?  Molecules are always moving. As they move they bump into each other.  The more molecules in an area the more they will collide.  Collisions cause molecules to move away from each other.  The molecules will continue to spread out until they are eventually evenly spread out throughout the area.

4. Diffusion of oxygen  There is higher concentration of oxygen molecules in water than inside the cell.  The cell membrane is permeable to oxygen molecules.  Oxygen molecules diffuse from the higher concentration to lower concentration

5. Osmosis!!  Osmosis- is the diffusion of water molecules through a selectively permeable membrane  Because cells cannot function properly without adequate water, many cellular processes depend on osmosis.

6. Osmosis and diffusion  In osmosis water molecules move by diffusion from an area where they are highly concentrated through the cell membrane to an area where they are less concentrated.

7. Effects of osmosis  9A, concentration of water is the same as it is inside the cell (normal shape)  9B, the concentration of water molecules outside the cell is lower than the concentration of water molecules inside the cell. (water moves out)  9C, the concentration of water outside the cell is greater than it is inside the cell. (water moves in)

8. Active transport  Passive transport- the movement of dissolved materials through a cell membrane without using cellular energy. (down hill)  Active transport- the movement of materials through a cell membrane using cellular energy. (up hill)  Active transport requires the cell to use its own energy, while passive transport does not.

9. Active Transport proteins  Transport proteins-  in the cell “pick up” molecules outside the cell and carry them in, using energy.  Can also carry molecules out of the cell  Substances that are carried include calcium, potassium, and sodium

10. Active transport by engulfing  The cell membrane surrounds and engulfs, or encloses, a particle  One the particle is engulfed, the cell membrane wraps around the particle and forms a vacuole within the cells.