Osmosis vs. Diffusion Diffusion: The movement of molecules from high to low concentration Osmosis: The movement of water through a selectively permeable membrane from high water concentration to low water concentration

Red Blood Cells Homeostasis- a cell’s ability to maintain equilibrium (balance) or stability If water continues to move in, CYTOLYSIS will result (cell bursts) If water continues to move out of the cell Plasmolysis results (cell shrivels)

Passive Transport NO energy needed ALWAYS - high to low concentration Example: Oxygen moving from lungs into a red blood cell.

ACTIVE TRANSPORT REQUIRES ENERGY! Movement from Low Concentration to High Concentration. (an uphill battle!)

Endocytosis Exocytosis Movement in Vesicles 2 Types: For macromolecules (large molecules) and nutrients which are too big for the other methods 2 Types: Endocytosis endo – within- enter Cyto- cell Exocytosis exo – without-exit Cyto-cell

Endocytosis Exocytosis Used to engulf large particles Called “cell eating” Moving large molecules OUT of the cell (EXIT) Reverse of endocytosis Removes waste from cell Exocytosis

Endocytosis Outside the cell cytoplasm Used to engulf large particles such as food, bacteria, etc. into vesicles Called “Cell Eating”

Moving the “Big Stuff” Exocytosis- moving things out. Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. This is how many products and waste are secreted

Exocytosis The opposite of endocytosis is exocytosis Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. Inside Cell Cell environment

Endocytosis and Exocytosis in Action http://www.stolaf.edu/people/giannini/flashanimat/cellstructures/ph agocitosis.swf