1. How Cells Exchange Materials

2. Diffusion The random movement of atoms, molecules and small particles from an area of high concentration to an area of low concentration. No energy (ATP) required.

3. Osmosis Diffusion of water across a membrane Does not require ATP

4. Permeable: able to pass through Impermeable: not able to pass through

5. Semipermeable or Differentially Permeable Membrane Some substances can pass through and others can’t Either due to their size or electrical charge Ex. Plasma Membrane, Nuclear Membrane

6. Facilitated Diffusion Sometimes, large molecules cannot cross the plasma membrane, and are "helped" across by carrier proteins - this process is called facilitated diffusion. It uses ATP

8. Active Transport Uses ATP Cell moves substances against the concentration gradient (from low concentration to high concentration)

9. Sodium Potassium Pump

11. Endocytosis Cell engulfs some of the material around it. A portion of the plasma membrane is invaginated and pinched off forming a membrane-bound container

12. Exocytosis A membrane bound part of the cell is moved to the cell membrane and its contents are ejected from the cell. Comes from Golgi Complex

13. Phagocytosis The cell engulfs those things that it “wants” Occurs sporadically and in only a few types of cells Forms vacuoles “cell eating”

14. Pinocytosis The engulfed material is relatively small Occurs in nearly every cell “cell drinking”

15. Isotonic If the concentration of solute (salt) is equal on both sides, the water will move back in forth but it won't have any result on the overall amount of water on either side. Iso- means “the same”

16. Hypertonic Hyper means more There are more solute (salt) molecules outside the cell, which causes the water to move in that direction. Cells shrink as they lose water. Egg in salt water is hypertonic and will lose water.

17. Hypotonic Hypo means less There are fewer solute (salt) molecules outside the cell so water will move into the cell. The cell will gain water and grow larger. In animal cells, organelles called CONTRACTILE VACUOLES will pump water out of the cell to prevent this. The egg in fresh water is hypotonic and water will enter the egg.