Diffusion and Osmosis: Understanding Concentration Gradients and Cell Membrane Movement

1. 3.4 Diffusion 2.1 Atoms, Ions, and Molecules Sponge: Set up Cornell Notes on pg. 29 Topic: 3.4 Diffusion Essential Question: Explain what a concentration gradient is and what it means for a molecule to diffuse down its concentration gradient. Explain what a concentration gradient is and what it means for a molecule to diffuse down its concentration gradient. Key Concept: Materials move across membranes because of concentration differences.

2. Table P.28 Concentration Gradient

3. 3.4 Diffusion and Osmosis • KEY CONCEPT Materials move across membranes because of concentration differences.

4. 3.4 Diffusion and Osmosis • Solution: A homogenous mixture of two or more substances, which may be solids, liquids, or gases, or the combination of these. • Ex: Sugar water • Solute: Substance dissolved in another substance • Ex: Sugar • Solvent: Substance doing the dissolving (usually the substance present in the greatest amount) • Ex: Water (THE BEST SOLVENT)

5. Which one is the Solute? Solvent? Solution? • Milk Chocolate Milk Chocolate Syrup • Solution • Solvent • Solute • Air Nitrogen (78%) Oxygen, argon, CO2 (22%) • Solution • Solvent • Solute

6. 3.4 Diffusion and Osmosis • Passive transport- the movement of molecules across a cell membrane without energy input from the cell • There are two types of passive transport. 1. diffusion 2. osmosis

7. Pg. 28

8. Fill Out • Pg. 28

9. Pg. 28

10. Diffusion Demonstration • Materials: 2 Cups, Water, Dye, Salt, Graph • Identify the solvent, solute, and solution for each demonstration • Hypothesize what is going to happen when you drop the food coloring in the water. Salt in the water? • Did your hypothesis match the results?

11. Pg. 28

12. 3.4 Diffusion and Osmosis • Diffusion: is the movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration.

13. Air Freshener Demo.

14. 3.4 Diffusion and Osmosis • Diffusion: is the movement of molecules in a fluid or gas from a region of higher concentrationto a region of lower concentration.

15. 3.4 Diffusion and Osmosis • Diffusion: is the movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration.

16. Diffusion Demonstration • Materials: 2 Cups, Water, Dye, Salt, Graph • Identify the solvent, solute, and solution for each demonstration • Hypothesize what is going to happen when you drop the food coloring in the water. Salt in the water? • Did your hypothesis match the results? • Explain how these experiments demonstrated diffusion

17. Pg. 28

18. Concentration gradient- the difference in the concentration of a substance from one location to another. • Molecules diffuse down their concentration gradient • Bottom pg. 28

19. How Diffusion Works https://www.youtube.com/watch?v=VY0mZUDvbH4

20. 3.4 Osmosis 2.1 Atoms, Ions, and Molecules Sponge: Set up Cornell Notes on pg. 31 Topic: 3.4 Osmosis Essential Question: A cell is bathed in fluid. However, you notice that water is flowing out of the cell. In what kind of solution is this cell immersed? A cell is bathed in fluid. However, you notice that water is flowing out of the cell. In what kind of solution is this cell immersed?

21. Hypotonic Solution Isotonic Solution Hypertonic Solution Video Notes Osmosis Pic Pg. 30

22. 3.4 Diffusion and Osmosis • Osmosis is the diffusion of water molecules across a semipermeable membrane.

23. The water will continue to move across the membrane until it reaches “equilibrium” or an isotonic state Draw on Pg. 30

24. 3.4 Diffusion and Osmosis • There are three types of solutions. • Same amount of solutes/water inside and outside cell • = amounts of water enter and leave the cell • Stays the same size!

25. 3.4 Diffusion and Osmosis • There are three types of solutions. • More solutes outside the cell than inside the cell • More water inside the cell than outside the cell • More water exits cell • Shrinks!

26. 3.4 Diffusion and Osmosis • There are three types of solutions. • More solutes inside the cell than outside the cell • More water outside cell than inside the cell • More water enters cell • Expands!

27. Osmosis Videos Video Notes on P. 30 (15-20 bullets/examples) • Osmosis vs. Diffusion • Osmosis Computer Graphics • Osmosis Demo Video • Osmosis with a U-tube • Osmosis in the kitchen • Osmosis with an Egg • Desalination- Reverse Osmosis

28. 3.4 Diffusion and Osmosis • Some molecules cannot easily diffuse across the cell membrane Ex: H2O • Facilitated diffusion is diffusion through transport proteins • Things like H2O would be repelled by the phospholipid tails, so transport proteins allow the H2O to diffuse easily

29. GUMMI BEAR LAB- OSMOSIS

30. Gummi Bear Osmosis Lab • Table 1: Predictions and Conclusions

31. Osmosis Lab Materials • Materials: • 1 cup Water Sugar • 1 Gummi Bear Scale (g) • Ruler (mm) String (for width) • Salt • Label each cup: First/Last Name Period #

32. Day One: Gathering Data • Weigh your Gummi Bear and record its weight (g) • Measure your Gummi’s length and width (mm) • Place the Gummi in a 25/75 sugar/water solution • Fill in your table with your hypothesis

33. Day Two: Gathering Data • Dry your Gummi bear off carefully • Weigh your Gummi Bear and record its weight (g) • Measure your Gummi’s length and width (mm) • Was your hypothesis correct? What happened to your Gummi? Compare this data with your group data, and record on Lab report tables. • Rinse out your cup and rinse off your gummi (quick and carefully) • Place the Gummi in a 100% distilled water • Fill in your table with your new hypothesis

34. Day Three: Gathering Data • Dry your Gummi bear off carefully • Weigh your Gummi Bear and record its weight (g) • Measure your Gummi’s length and width (mm) • Was your hypothesis correct? What happened to your Gummi? Compare this data with your group data, and record on Lab report tables. • Rinse out your cup and rinse off your gummi (quick and carefully) • Place the Gummi in a 25/75 solution of salt and water • Fill in your table with your new hypothesis