Movement of Materials
The Cell Membrane
Plasma Membrane (aka Cell Membrane) Phosopholipid Bilayer Called the Fluid Mosaic Model 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
Active (requires NRG) Passive (no NRG) Types of Transport
Osmosis Passive Passive Transport Diffusion 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
Passive Transport 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 Animal Cell SolutionBeforeAfter Isotonic Hypotonic Hypertonic
Explain what is happening in this cartoon…
Facilitated Diffusion Diffusion that is helped by proteins in the membrane
Facillitated Diffusion
Diffusion vs. Facillitated Diffusion
Membrane Movements Active Active Transport Pumps Endocytosis Exyocytosis
Active Transport Movement of materials from low concentration to high concentration using a protein carrier that requires energy (costs ATP)
Active Transport High Concentration 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