1. Diffusion - Ions and other particles move randomly due to kinetic energy. They move from areas of higher concentration to lower concentration until dynamic equilibrium is reached.

2. Needed materials may enter a cell by diffusion across membrane. By-products of cell metabolism may diffuse out. E.g., - water, lipids, lipid-soluble molecules, and gases may permeate membranes.

3. Movement of water into and out of cells across the membrane is called osmosis.

4. Osmosis is the diffusion of water through a semipermeable membrane.

5. Osmotic balance is dynamic equilibrium that occurs when the amount of water entering and leaving a cell is equal.

6. E.g., Red blood cell in vessels is in balance. If placed in water will swell and burst. Equilibrium is destroyed.

7. E.g., Elodea in salt water will shrink (plasmolysis). Equilibrium is destroyed.

8. Isotonic solution - in equilibrium.

9. Hypotonic solution - higher water concentration outside. Having a lower osmotic pressure than the solution.

10.Hypertonic solution - higher concentration inside. Having a lower osmotic pressure than the solution.

11. Concentration differential: When there is a difference in concentration inside and outside cell - not in equilibrium.

12. Concentration gradient: The difference between high and low concentrations.

13. When particles are small enough to pass through pores or dissolve into lipids in membrane, passage is due to kinetic energy. The cell plays no active role: Passive Transport.

14. When certain ions, sugars, and amino acids are in greater concentration outside the cell, but cannot enter - Facilitated Diffusion. 15. This is use of proteins in membrane to facilitate passage of particles from region of greater concentration to lower.

16. Proteins involved in facilitated diffusion are known as permeases.Form pores or channels in integral proteins.

17. Different ions pass through different ores. Depends on size and charge of ion.

18. Some permeases aid in passage of two particles at once. Glucose and sodium pass together.

19. Sodium ion outside cell is picked up by protein. This changes permease's shape. This allows pick up of glucose. It then closes to outside and opens to inside. Particles enter cell.

21. Active Transport: When cell uses its energy to move particles from lower to higher concentration (against concentration gradient). Requires up to 40% of cell's ATP use.

22. Permeases (integral proteins) are also involved. Act as "carrier" molecules or channels.

23. E.g., glucose in intestine move into blood circulation against concentration gradient through channels.

24. Endocytosis - process in which a cell uses energy to surround and take in large particles.

25. Phagocytosis - pseudopodia of cell surround particle. Sac or vesicle is formed inside (particle doesn't pass through membrane). Digestive organelle (lysosome) attaches. Process requires energy. E.g., amoeba, white blood cells.

26. Pinocytosis is the taking in of liquid droplets or very small particles.

27. Exocytosis is reverse process used to rid some cells of wastes or expel useful substances needed elsewhere. 28. Vesicle moves to membrane. Two membranes fuse and vesicle bursts. Materials are expelled. Process requires energy.