2. Regents Biology Cell Membranes & Movement Across Them 2006-2007

3. Regents Biology DO NOW  Do you smell the popcorn?  Do you see the pink stuff slowly moving in the cell?  What do these two occurrences have in common?  Make a list with a partner of other everyday occurrences that happen for the same reason.

4. Regents Biology Cellular Transport 1. Processes involved: a. Absorption – To take in, substances must pass through the cell membrane b. Circulation – movement of materials inside a cell or around an organism

5. Regents Biology 2. Cell Membrane Structure a. Phospholipid bilayer – proteins, lipids, carbohydrates. b. Fluid Mosaic Model – lipid layers are in a constant flexible, fluid state.

6. Regents Biology Lipids of cell membrane  Membrane is made of special kind of lipid  phospholipids  “split personality”  Membrane is a double layer  phospholipid bilayer inside cell outside cell lipid “repelled by water” “attracted to water” phosphate

7. Regents Biology 2. Cell Membrane Structure c. Selectively Permeable i. Some substances CAN pass through ii. Some can only pass through AT CERTAIN TIMES iii. Some CANNOT pass through aa H2OH2O sugar lipidssalt waste So what needs to get across the membrane? O2O2

8. Regents Biology Regents Question

9. Regents Biology Transport Vocabulary Solution – mixture of solvent + solute (Saltwater Solution) Solute – dissolved particles (Salt) Solvent – liquid that dissolves solute (Water)

10. Regents Biology Passive Transport (Diffusion) 1. Diffusion – movement across a membrane a. Concentration gradient – high to low b. Moves across gradient until equilibrium is reached Concenration Gradient: NO ENERGY !!!

11. Regents Biology Simple Diffusion  Move from HIGH to LOW inside cell outside cell Which way will fat move? fat LOW HIGH

12. Regents Biology Passive Transport (Diffusion) 2. Osmosis – Diffusion of Water across a membrane Water Salt 100% W 5% S 95% W

13. Regents Biology Regents Question

14. Regents Biology Regents Question

15. Regents Biology Regents Question

16. Regents Biology Turgor Plasmolysis

19. Let’s Apply this to a Real Situation  What causes human blood cells to swell or shrink?

20. Regents Biology Hypertonic Solution  When the solution inside the blood cell has a high solute concentration than its environment, the cell is said to be hypertonic to its environment.  Water will diffuse in. The cell cannot get rid of the water fast enough, and the cell swells and lysis.

21. Regents Biology Hypotonic Solution  When the solution inside the cell has a lower concentration of solute than its environment, the cell is said to be hypotonic to its environment.  Water will diffuse out of the cell, causing the cell to shrink or crenate.

22. Regents Biology Isotonic Solution  When the solute concentration outside the cell is equal to the solute concentration inside the cell, the cell retains its shape.

23. Regents Biology DO NOW  Movie Madness  What does your mouth feel like before eating salty movie popcorn?  What does your mouth feel like after eating the popcorn?  Why do you think this occurs? Hint: Think about what is happening to the cells inside your mouth.  Why do you think movie theaters put a lot of salt on their popcorn?

24. Regents Biology Practice  Why is the water leaving the cell?  The cell is hypotonic to the environment.  What must be done to allow the water to reenter the cell?  Dilute the outside salt concentration by adding water  What does the 3 and 5 % represent?  solute 3% salt 5% salt

25. Regents Biology Crossing the cell membrane  What molecules can get through the cell membrane directly?  Fats, oils, and very small molecules inside cell outside cell lipid salt aa H2OH2O sugar waste but… what about other stuff?

26. Regents Biology FACILITATED DIFFUSION:  Need “doors” through membrane  protein channels allow substances in & out that cannot cross otherwise  specific channels allow specific material in & out  Ex. H 2 O channel, salt channel, sugar channel, etc. inside cell outside cell sugaraa H2OH2O salt waste

27. Regents Biology Facilitated Diffusion  Move from HIGH to LOW through a channel inside cell outside cell sugar Which way will sugar move? sugar LOW HIGH

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29. Active Transport 1. Requires the use of energy (ATP) 2. Movement is against the concentration gradient (low to high) Concentration Gradient: REQUIRES ENERGY!!!

30. Regents Biology Active Transport 3. Types: a. Pinocytosis – cell membrane engulfs small amounts of liquid b. Phagocytosis – solid particles are engulfed by cell.

31. Regents Biology Regents Question

32. Regents Biology Regents Question Cyanide is a poison that limits the ability of an animal cell to manufacture ATP. In a cell containing a small amount of cyanide, which process would be least affected? 1. Cell division3. movement 2. Active transport4. diffusion

33. Regents Biology Cellular Transport REVIEW 1) What is meant by the fluid-mosaic model? 2) Define diffusion. 3) How are diffusion and osmosis similar? Different? 4) How are diffusion and active transport different? List 2 ways.

34. Regents Biology