1 2-7 Diffusion

2 Molecules Molecules are the smallest part of a substance that still have the characteristics of that substance. Molecules are the smallest part of a substance that still have the characteristics of that substance. Molecules are always moving Molecules are always moving

3 Diffusion is.. Movement of material from an area where molecules are crowded to an area where they are less crowded. Movement of material from an area where molecules are crowded to an area where they are less crowded. usion.gif usion.gif usion.gif usion.gif

4 Passive Transport Is diffusion through cell membranes Is diffusion through cell membranes emb/c8.7x11.diffusion.jpg emb/c8.7x11.diffusion.jpg emb/c8.7x11.diffusion.jpg emb/c8.7x11.diffusion.jpg

5 OSMOSIS Osmosis is the movement of water molecules through a membrane Many substances dissolve in water. Water plus the dissolve substance move through the cell membrane hhhh tttt tttt pppp :::: //// //// wwww wwww wwww.... ssss tttt jjjj oooo hhhh nnnn.... aaaa cccc.... tttt hhhh //// DDDD eeee pppp aaaa rrrr tttt mmmm eeee nnnn tttt //// ssss cccc hhhh oooo oooo llll //// bbbb iiii oooo ____ pppp iiii xxxx //// oooo ssss mmmm oooo ssss iiii ssss.... gggg iiii ffff

6 What do you think? What would happen if water constantly entered a cell, and none left it? What would happen if water constantly entered a cell, and none left it?

7 It will burst

8 Active Transport The cell may need more of a substance inside the cell than outside. The cell may need more of a substance inside the cell than outside. This requires molecules to move in the opposite direction they would normally move. This requires molecules to move in the opposite direction they would normally move. Energy is required for molecules to move from less crowded to more crowded areas. Energy is required for molecules to move from less crowded to more crowded areas. _active1_240x180.gif _active1_240x180.gif _active1_240x180.gif _active1_240x180.gif