Diffusion and Osmosis

1. Diffusion and Osmosis Start

2. TABLE OF CONTENTS Diffusion Osmosis Living Cell Osmosis Diffusion and Osmosis

3. DIFFUSION Dialysis Equipment Equipment Set Up Results Diffusion and Osmosis

4. Diffusion (Dialysis Equipment) glass dish dialysis tubing glucose test strips closures pipet Diffusion and Osmosis

5. Starch Water Glucose Initially, the dialysis tubing is filled with a super saturated glucose + starch solution dialysis tubing continue animation Diffusion and Osmosis

6. Starch Water Glucose The filled dialysis tubing is placed in a dish with a solution of iodine and water Iodine Water The dialysis tubing membrane is selectively permeable continue animation Diffusion and Osmosis

7. Diffusion (Equipment Set Up) DIALYSIS TUBING starch, glucose and water iodine and water Diffusion and Osmosis

8. In DIFFUSION, particles travel from an area of high concentration to an area of low concentration As particles migrate through a membrane in this way, movement is described to be traveling “down a concentration gradient” Diffusion and Osmosis

9. When particles migrate through a selectively permeable membrane some particles are able to pass through but not others Diffusion and Osmosis

10. Starch Water Glucose There is a GLUCOSE gradient across the membrane Iodine Water NONE HIGH GLUCOSE molecules fit through the membrane and travel “down a concentration gradient” to the outside of the dialysis tubing … testing indicates GLUCOSE now in dish continue animation Diffusion and Osmosis

11. There is a IODINE gradient across the membrane Iodine Water HIGH Starch Water Glucose NONE IODINE molecules fit through the membrane and travel “down a concentration gradient” to the inside of the dialysis tubing … testing indicates IODINE now in dialysis tubing as Starch turns PURPLE continue animation Diffusion and Osmosis

12. There is a STARCH gradient across the membrane Iodine Water NONE Starch Water Glucose HIGH However, STARCH molecules cannot fit through the dialysis tubing membrane … water in dish is not PURPLE continue animation Diffusion and Osmosis

13. There is a WATER gradient across the membrane Iodine Water HIGH LOW Starch Water Glucose WATER molecules fit through the membrane and travel “down a concentration gradient” to the inside of the dialysis tubing … dialysis tubing is much fuller than before continue animation Diffusion and Osmosis

14. Diffusion (Results) dialysis tubing in iodine and water Diffusion and Osmosis

15. OSMOSIS Osmometer Equipment Equipment Set Up Results Diffusion and Osmosis

16. OSMOSIS (Osmometer Equipment) cup animal disc membrane bell straw cover rubber band pipet Diffusion and Osmosis

17. ASSEMBLING THE OSMOMETER straw inserted into narrow end of bell cup with lid bell opened at both ends selectively permeable membranestretched across wide end of bell continue animation Diffusion and Osmosis

18. FILLING THE OSMOMETER The position of the solution in the bell is marked The bell is filled with a super saturated lactose solution (lactose and water) The solution is dyed to make it visible in the bell The cup is filled one half full of water continue animation Diffusion and Osmosis

19. A super saturated solution has a relatively low water concentration because of a VERY HIGH solute concentration The osmometer solution has a large amount of lactose solute dissolved in a small amount of water Diffusion and Osmosis

20. The osmometer is assembled continue animation Diffusion and Osmosis

21. Osmosis (Equipment Set Up) fluid level super saturated lactose and water solution water Diffusion and Osmosis

22. OSMOMETER Diffusion of water takes place through the membrane. Water is pulled from an area of high concentration (in the cup) to an area of low concentration (in the bell) continue animation Diffusion and Osmosis

23. As water diffuses through the membrane OSMOMETER “down the gradient” from the cup into the bell the overall fluid level rises up the straw continue animation Diffusion and Osmosis

24. The membrane is selectively permeable OSMOMETER the lactose solute particles because of their larger size are prevented from migrating through the membrane and rise up the straw along with the water continue animation Diffusion and Osmosis

25. Osmosis (Results) fluid level osmometer solution rises up the straw water is pulled in through selectively permeable membrane Diffusion and Osmosis

26. LIVING CELL OSMOSIS Elodea Before NaCl Application 400x Elodea Before NaCl Application 1000x Elodea After NaCl Application 400x Elodea After NaCl Application 1000x Diffusion and Osmosis

27. Elodea Before NaCl Application 400x Diffusion and Osmosis

28. Elodea Before NaCl Application 1000x cell wall cell membrane chloroplasts continue animation Diffusion and Osmosis

29. 100% water 100% water 100% water The cell is initially in an isotonic solution Water within the cell keeps the cell membrane against the cell wall Chloroplasts are evenly spread throughout the cytoplasm continue animation Diffusion and Osmosis

30. The cell is placed in a hypertonic salt solution Elodea 1000x continue animation Diffusion and Osmosis

31. 90% water 90% water water water 10% salt 10% salt Hypertonic Solution Hypertonic Solution water water When the cell is placed in a hypertonic solution there is a salt gradient across the cell wall and membrane Water goes “down the gradient” from a high water concentration inside of the cell ... 100% water to a low water concentration outside of the cell continue animation Diffusion and Osmosis

32. Elodea After NaCl Application 400x continue animation Diffusion and Osmosis

33. water water water water The rigid cell wall is porous and remains intact ... but without water inside of the cell, the cell membrane is pulled from the cell wall Hypertonic Solution Hypertonic Solution Chloroplasts are draw in with the cell membrane and collect in the middle of the cell continue animation Diffusion and Osmosis

34. cell membrane cell wall Water is pulled out of cell through the cell wall into hypertonic solution chloroplasts The cell membrane separates from the cell wall The cell membrane crenates pulling chloroplasts into a small bunch Elodea After NaCl Application 1000x End Diffusion and Osmosis