1. Solution - a homogeneous mixture of 2 substances Solute - the dissolved substance Solvent - the dissolving agent

2. Diffusion Random movement of molecules from an area of their higher concentration to an area of their lower concentration. Lighter molecules diffuse faster than heavier molecules

3. Diffusion occurs in both liquids and gases. Examples: sugar in water; perfume in air.

4. Osmosis Diffusion of water molecules through a semi- permeable membrane from an area of higher water concentration to an area of lower water concentration (An area of high water concentration has a low solute concentration, and visa versa)

5. Copyright © 2009 Pearson Education, Inc. Figure 3.7 Generation of osmotic pressure by osmosis.

6. Solute concentrations of outside solutions relative to the inside of a cell: Isotonic: the same solute concentration Hypertonic: higher solute concentration Hypotonic: Lower solute concentration The plasma membrane is a semi-permeable membrane. The cytoplasm is completely enclosed.

7. Osmosis and Cells

8. Osmosis and cells In hypertonic environment, the cell shrinks. In a plant cell, this is called plasmolysis: the cell shrinks inside the cell wall. In hypotonic environment, the cell swells. An animal cell will burst, which is called lysis.

9. Differences between dialysis tubing and the cell membrane (both are selectively permeable): 1.Dialysis tubing has pores. Whether or not a molecule can cross depends only on its size. 2.The cell membrane is made of a lipid bilayer. Whether or not a molecules can cross depends on its chemical properties. 3.Proteins are embedded in the membrane, and regulate the passage of most molecules across the membrane.

10. Copyright © 2009 Pearson Education, Inc. Membrane Lipids: basic structure tailshead

11. Copyright © 2009 Pearson Education, Inc. The plasma membrane. (DON’T NEED TO KNOW THE DETAILS)