1. What does a cell need to survive and how does it get that?

3. Lipid Bilayer- a double-layered group of lipids (fats) that protect the cell, allowing only some things in and out of the cell. Semipermiable- A membrane that can select what materials can move through.

4. All cells have a liquid inside Reminder: liquid = solvent other = solute Concentration- the amount of solute in an area. When solutes move from areas of high to low concentration, across the cell’s membrane, the process is called diffusion.

5. In other words, things move across a membrane from areas of “a lot” to areas of “a little”. It’s all about size and shape chemicals are too big or the wrong shape, they cannot pass through the membrane

6. **This does not cost the cell energy!

7. Most semipermiable membranes allow water to cross. When WATER moves from high to low concentration, the process is called osmosis. Animation: http://www.colorado.edu/eeb/web_resources/osmosis/http://www.colorado.edu/eeb/web_resources/osmosis/

8. Molecules need to get in, but can’t by diffusion. Many proteins in the cell membrane act to let recognize these molecules and allow them into the cell. **This does not require energy!

10. Many cells need certain chemicals in high concentrations. Many small molecules are pumped into a cell by special proteins. *This requires energy! **What makes that energy?

12. Endocytosis- Taking IN molecules by cell membranes folding into pockets. Phagocytosis- When large particles are taken in through endocytosis Pinocytosis- Cell taking in liquid Exocytosis- Vacuoles fuse with cell membranes, forcing molecules OUT.

15. Some Examples… Salt on a cell What happens? If concentration of things in and out of cell are very different and remain that way, what does that tell you about the cell’s functioning?

16. Breaking down glucose to create energy in the form of ATP Aerobic uses oxygen, makes 36 ATP Anaerobic when oxygen is absent, makes 2 ATP

17. What are 2 factors that allow some things to cross a membrane while others cannot?