- Slides: 16
Diffusion & Osmosis (Passive Transport)
Passive Transport u When materials are moved without using the cell’s energy u Osmosis and diffusion are 2 types of passive transport.
Define Diffusion The movement of molecules from a area in which they are highly concentrated to a area in which they are less concentrated.
example of diffusion
See an animation of diffusion here: http: //highered. mcgrawhill. com/sites/0072495855/student_vie w 0/chapter 2/animation__how_diffusion _works. html
Define osmosis u The diffusion of WATER across a selectively permeable membrane. Selective Permeability u A membrane that allows only certain materials to cross it u Materials pass through pores in the membrane
Osmosis u In this picture a red blood cell is put in a glass of distilled water (all water with no salt or sugar in it). Because there is a higher concentration of water outside the cell, water enters the cell by OSMOSIS. In this case too much water enters and the cell swells to the point of bursting open. In the end pieces of cell membrane are left in the water.
See an animation of osmosis here: http: //highered. mcgrawhill. com/sites/0072495855/student_vie w 0/chapter 2/animation__how_osmosis_ works. html
Why are osmosis & diffusion important?
Why are osmosis & diffusion important? All living things have certain requirements they must satisfy in order to remain alive – maintain homeostasis (stable environment) u These include exchanging gases (usually CO 2 and O 2), taking in water, minerals, and food, and eliminating wastes. u These tasks happen at the cellular level. u Molecules move through the cell membrane by diffusion u
Endocytosis and Exocytosis are ACTIVE TRANSPORT Active transport means that the cell needs energy to move the material through the cell. u Materials that are too large to move through the membrane are moved by endocytosis or exocytosis u Active transport is necessary because sometimes cells need to move materials from lesser concentrations to greater concentrations. (Kidneys use this process to remove excess salt) u
Endocytosis u Endocytosis moves materials into the cell. Exocytosis u Exocytosis move materials out of the cell. Endocytosis and Exocytosis are forms of Active Transport.
Exocytosis and Exocytosis u http: //bcs. whfreeman. com/thelifewir e 8 e/content/cat_040/0504003. html u http: //www. youtube. com/watch? v=l g. HJUk. GPBqs u http: //www. youtube. com/watch? v= Du. Dmvlbpj. HQ