Movement of Materials The Cell Membrane Plasma Membrane

Movement of Materials

The Cell Membrane

Plasma Membrane (aka Cell Membrane) • Phosopholipid Bilayer • Called the Fluid Mosaic Model • Selectively Permeable

Selectively Permeable If a membrane is selectively permeable only certain things can pass through

The Cell Membrane is Selective: • Things that passively cross: – Non-Polar Molecules (Alcohols, Steriods) – Small Molecules (Water) • Things that actively cross: – Polar Molecules (Ions) – Large Molecules

Types of Transport Passive (no NRG) Active (requires NRG)

Passive Transport Passive Diffusion Osmosis Facilitated Diffusion

Passive Transport Movement of materials that DOES NOT require energy (ATP)

What is happening here? ? ?

DIFFUSION The passive movement of material from an area of high concentration to an area of low concentration

Concentration The number of a substance in a specific area

High Concentration Low Concentration

Pa ss ive Tr an sp ort High Concentration Low Concentration

Factors Affecting Diffusion • Concentration—diffusion always goes from high concentration to low concetration • Temperature—the higher the temperature, the faster diffusion occurs • Molecular Size—the bigger the molecule, the longer diffusion takes

OSMOSIS The diffusion of water through a selectively permeable membrane

Osmosis—another look…

Osmotic Pressure The force (pressure) produced by water moving into a cell

Isotonic Solution No net movement of water in or out of the cell

Hypotonic Solution Water moves from the solution into the cell causing it to swell or break (lysis)

Hypertonic Solution The water moves out of the cell into the solution, causing the cell to shrink

Types of Solutions

Why doesn’t the plant cell undergo lysis?

WHITEBOARDING In your groups draw what the cells would look like in each case. Effect of Osmosis on Cells Solution Isotonic Hypertonic Before Animal Cell After

Explain what is happening in this cartoon…

Facilitated Diffusion that is helped by proteins in the membrane

Facillitated Diffusion

Diffusion vs. Facillitated Diffusion

Active Transport Active Pumps Membrane Movements Endocytosis Exyocytosis

Active Transport Movement of materials from low concentration to high concentration using a protein carrier that requires energy (costs ATP)

High Concentration t por s ran e. T tiv Ac Low Concentration

What was ATP again? ? ?

Sodium-Potassium Pump

Active Transport

Endocytosis Process of bringing particles into a cell using extensions of the cellular membrane

Exocytosis Process of moving particles out of a cell using extensions of the cellular membrane (how wastes are excreted from cells)

Endocytosis y Exocytosis

Phagocytosis The process of membrane folding that enables cells to bring “food” into the cell

Pinocytosis The process of membrane folding that enables cells to bring “water” into the cell