Cellular Transport Diffusion Osmosis Facilitated Diffusion Active Transport

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. H 2 0

Hypotonic Solution • Concentration of solutes is lower in solution than inside cell. • Net movement of water will be INTO the cell. H 2 0

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

Hypotonic Solutions

Hypertonic Solution • Concentration of solutes is greater in solution than inside cell. • Net movement of water will be OUT OF the cell. H 2 0

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. High Potassium K+ Na+ Low Sodium 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)