Cellular Transport

1. Cellular Transport Diffusion Osmosis Facilitated Diffusion Active Transport Filtration

2. Passive Transport • NO ENERGY REQUIRED to move substances across membrane -- water, lipids, and other lipid soluble substances. • Types: • Diffusion • Osmosis • Facilitated Diffusion • Filtration

3. Diffusion • Occurs because of Brownian Motion, i.e., the random movement of particles. • Net movement of particles from an area of greater concentration to an area of lesser concentration. • Concentration gradient, i.e., the difference in concentration across space.

4. Diffusion Molecules move down the concentration gradient until there are equal numbers of molecules on both sides ~ dynamic equilibrium.

5. Dynamic Equilibrium Molecules continue to move randomly because of Brownian motion, but there is no net movement.

6. Osmosis • Diffusion of water from an area of greater concentration of water to an area of lesser concentration of water -- across a semipermeable membrane. • Isotonic Solutions • Hypertonic Solutions • Hypotonic Solutions

7. Isotonic Solution • Concentration of solutes in the solution is the same as inside the cell. • Cell is in dynamic equilibrium, i.e., no net gain or loss of water. H20 H20

8. Hypotonic Solution • Concentration of solutes is lower in solution than inside cell. • Net movement of water will be INTO the cell. H20 H20 H20

9. Hypotonic Solution Turgor Pressure -- This is why grocery stores spray vegetables -- crispness! Plant Cell Cytolysis -- Animal cell bursts. Animal Cell

10. Hypotonic Solutions

11. Hypertonic Solution • Concentration of solutes is greater in solution than inside cell. • Net movement of water will be OUT OF the cell. H20 H20 H20

12. Hypertonic Solutions • Meat placed in salt water loses moisture and is dry and tough when cooked. • Plant cells placed in salt water shrink, losing turgor pressure ~ plasmolysis. • Blood cells in hypertonic solutions will lose liquid ~ plasmolysis.

13. Facilitated Diffusion • Movement across the membrane with the help of transport proteins . • Types: • Carrier protein - its shape fits certain molecules. • Channel protein- molecules diffuse through channel.

14. Active Transport • Transport of materials against (low to high) a concentration gradient • REQUIRES ENERGY! • Large Molecules: • Endocytosis/Exocytosis • Molecule engulfed by portion of membrane. • Portion breaks off as vacuole inside cell. • Liquid = Pinocytosis • Solids = Phagocytosis

15. Active Transport • Sodium-Potassium Pump • transports sodium ions out of cell, potassium ions into cell. High Potassium K+ High Sodium Low Potassium Na+ Low Sodium

16. Review • Types of Cellular Transport • Diffusion: Movement of solute (high to low) • Osmosis: Movement of water (high to low) • Hypotonic, Isotonic, and Hypertonic • Facilitated Diffusion: Carrier and channel proteins; Does not require energy • Filtration • Active Transport -- Requires energy • Endocytosis, Pinocytosis, Phagocytosis, Exocytosis, Some Carrier Molecules (Sodium-Potassium Pump)