1. Chapter 5 Cell Membrane DiffusionOsmosis

2. Is an organelle with a job Regulates what enters and leaves Flexible structure Strong barrier

5. Lipid Bi- layer Water, oxygen, and carbon dioxide flow freely through the lipid bi-layer

7. Besides lipids the cell membrane also contains –Protein molecules: form channels and pumps to help move material across the cell membrane –Carbohydrate molecules attached to proteins…. act like ID cards, so cells can identify each other

9. Cell Wall porous enough to allow water, oxygen, carbon dioxide, and certain other substances to pass through easily provide support and protection for the cell. composed mostly of cellulose, a tough carbohydrate fiber (this is why we can make clothes out of plant matter)

11. Concentration Lab The concentration of a solution is the mass of solute in a given volume of solution, or……… mass/volume. What are the units for mass and vol? Concentration gradient: is a comparison of where the greatest concentration is, and where its moving

12. In this lab you need to make a solution that is : 90% water and 10% sugar, …and another that is 80% water and 20% sugar. How will you do that?

13. Diffusion In a solution (liquid), particles move constantly. (Brownian movement) They collide with one another and tend to spread out randomly.

14. Diffusion The particles move from where it is too crowded…. to an area where there is more room… this is called diffusion In other words…from areas of High concentration to areas of Low concentration

16. In this Lab… Fill beaker with tap water Take temperature, and log it Put 2 drops of food coloring and time how long it takes to diffuse to the point of equilibrium Repeat this with Hot Water

17. Diffusion EZ pass analogy: –Tolls are up to $6 to cross the tunnels into NYC –They are going to raise it even higher, during rush hour…(6am-9am) and (4-7pm) –If they don’t really need the money then why would they do that?

18. Equilibrium The particles keep moving and eventually both areas are balanced….this is called equilibrium. Particles will continue to move back and forth but because numbers are equal, no change in concentration

19. Diffusion across membranes Diffusion is the simplest kind of passive transport in cells Passive means no energy required –The Brownian collisions do it all

20. Selectively permeable The cell membrane picks and chooses what can get through….. –Some particles have charges that repel –Some are too big –Some are polar –…..which is why they can’t get through

22. Cell Membrane Model What does the cotton tip represent? The q-tip stick? What substances cross easily? If you are too big you must pass through where? Ex?

24. Diffusion Solute is what dissolves or diffuses… Solvent is what you dissolved something in…. What was the solute? What was the solvent? What is the pattern of diffusion? –Down the concentration gradient Does it require energy? If I stirred it, would it spread faster? Would that still be considered diffusion?

26. Diffusion through a semi perm-membrane What does the baggie represent? Which substance was allowed to move through the bag? What does semi-permeable mean?

27. Selectively Permeable Mini-Lab Water vs. Air….and the rubber balloon…..