Ch. 4- Membrane Structure & Function

1. Ch. 4- Membrane Structure & Function Ch. 4.2- Permeability of the Plasma Membrane

2. Target #6- I can describe the passage of molecules through the plasma membrane • The plasma membrane regulates the passage of molecules into and out of the cell • Membrane is differentially(selectively) permeable certain substances can move across the membrane while others cannot • Water and small, uncharged particles, can freely cross the membrane • Able to slip between the phospholipids • Go down the concentration gradient move from areas of high concentration to areas of low concentration • Large molecules and ions are unable to freely pass through the membrane • Cross through channel proteins, carrier proteins, or vessicles

3. Diffusion: the movement of molecules from a higher concentration to a lower concentration until equilibrium • Down the concentration gradient • Occurs with only a few types of molecules • A solution contains a solute, a solid, and a solvent, a liquid • Ex: when we breathe in oxygen, the concentration is higher in the lungs, and then moves to the area of lower concentration, the blood Target #7- I can explain diffusion

4. Target #8- I can list the factors that affect diffusion • Several factors influence the rate of diffusion • Temperature • Pressure • Electrical currents • Molecular size

5. Target #9- I can define osmosisTarget #10- I can describe isotonic solutions • Osmosis: the diffusion of water across a differentially permeable membrane due to concentration differences • Isotonic solutions: the solute concentration and the water concentration both inside and outside the cell are equal • No net loss or gain of water

6. Hypotonic Solution • Solutions that cause cells to swell due to an intake of water • Concentration of solute is less on the outside of the cell then on the inside of the cell • Water enters the cell • Net movement of water is into the cell • Cytolysis: used to refer to ruptured cells • Turgor pressure: the swelling of a plant cell in a hypotonic solution Target #11- I can describe a hypotonic solution

7. Target #12- I can describe hypertonic solutions • Hypertonic Solution • Solutions that cause cells to shrink due to a loss of water • Higher percentage of solution in solution than the cell • Net movement of water is out of the cell • Crenation: refers to the shriveling of a cell in a hypertonic solution • Plasmolysis: shrinking of the cytoplasm in a plant cell due to osmosis