1. Ms. Sweeney 7 th grade Endeavor Science #3 Cell Transport

2. I. Structure of Cell Membrane A. Double layer of lipids (lipid bi-layer) B. Tiny pores that allow small molecules like oxygen and carbon dioxide to diffuse through C. Protein pumps are stuck in the cell membrane that allow larger molecules to pass through, like sugar

3. II. Passive Transport A. a cell’s membrane is selectively permeable. It only allows some things to enter or leave the cell B. passive transport- movement of substances through the cell membrane without the input of energy C. includes the following processes: diffusion, osmosis,

4. III. Diffusion A. molecules in gases liquids and solids are constantly moving at random B. diffusion- movement of molecules from areas of high concentration to areas of low concentration until equilibrium is reached C. equilibrium- when molecules of one substance are spread evenly through another substance (state of being equal)

6. IV. Osmosis A. osmosis- diffusion of water through a semi-permeable membrane B. if cells are placed in salt water, osmosis causes them to shrivel up. If they are placed in pure water, they will swell and possibly pop. A- normal solution B- pure water C- salt water

7. Go to http://www.youtube.com/watch?v=JShwXBWGMyYhttp://www.youtube.com/watch?v=JShwXBWGMyY To watch a short video about passive transport. The link is also in teacherweb

8. V. Active Transport A. active transport- when an input of energy is required to move materials through the cell membrane B. EX: when plants take in minerals from the soil even though the root might contain more of the mineral molecules than the soil

10. Go to http://www.youtube.com/watch?v=Kd3LorZcJewhttp://www.youtube.com/watch?v=Kd3LorZcJew And watch a short video on active transport. The link is also in teacherweb

11. VI. Endocytosis and Exocytosis A. Both a form of active transport (requires energy) B. endocytosis- process of taking substances into a cell by surrounding it with the cell membrane.

12. B. exocytosis- when the contents of a vesicle fuse with the cell membrane and the contents are released.

13. Go to http://www.youtube.com/watch?v=4gLtk8Yc1Zchttp://www.youtube.com/watch?v=4gLtk8Yc1Zc To watch a short video about endocytosis and exocytosis. The link is also on teacherweb

14. The End! – Review Passive transport- doesn’t require energy Diffusion-movement of molecules from high to low concentration Osmosis- diffusion of water across a semi-permeable membrane Active Transport- requires energy Protein pumps move materials across the cell membrane using energy Endocytosis- large materials brought in with a vesicle Excocytosis- large materials exit the cell using a vesicle