Osmosis, Diffusion, and Facilitated Diffusion Passive Transport Osmosis, Diffusion, and Facilitated Diffusion

Homeostasis The purpose of the cell membrane is to help the cell maintain homeostasis… A constant internal condition It allows the cell to control what enters and what leaves

Passive Transport Some molecules can easily cross the membrane Water, oxygen and carbon dioxide

Three forms of Passive Transport 1. Diffusion— Movement of molecules from high to low concentration The difference in these areas is called the concentration gradient Does not require energy Rate depends on temperature, size and type of molecule Faster at high temps, smaller, and short distance Continues until even on both sides

Three forms of Passive Transport 2. Osmosis— Movement of water High to low concentration (less to more water) Does not require energy Will occur until equal

3 types of osmotic solutions Hypertonic Solution Solute higher outside the cell Water will diffuse out of the cell until equilibrium Cells will shrink and die

3 types of Osmotic Solutions Hypotonic Solute concentration is higher inside (less water) Water moves into the cell until equal Animal cells will swell and burst Plants work best in this environment

3 types of Osmotic Solutions Isotonic Concentration of solute same inside and outside Water moves in and out freely Animal cells work best

3 forms of Passive Transport 3. Facilitated Diffusion Faster than normal diffusion No energy required High to low concentration Uses carrier proteins embedded in the membrane and channel proteins

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