Cellular Transport Diffusion Osmosis Facilitated Diffusion Active Transport Filtration

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

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.

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

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

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

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. H20H20 H20H20

Hypotonic Solution Concentration of solutes is lower in solution than inside cell. Net movement of water will be INTO the cell. H20H20 H20H20 H20H20

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

Hypotonic Solutions

Hypertonic Solution Concentration of solutes is greater in solution than inside cell. Net movement of water will be OUT OF the cell. H20H20 H20H20 H20H20

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.

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.

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

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

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)