1. How osmosis and diffusion relate to plants and animals.

2. Plant and Animal cells

3. Plasma membrane Plasma membranes consist of a phospholipid bilayer.
Two layers of phospholipids.

4. Passing through the plasma membrane
This Plasma Membrane is Semi-Permeable.
Some things can enter, other things can’t.
This means that only certain molecules can pass through, like small uncharged molecules such as O2, CO2, N2, H2O, Ethanol, and Glycerol.
Large molecules such as glucose cannot fit!

5. What a Phospholipid looks like…
Polar Hydrophilic (water loving) head
Non-polar Hydrophobic (water fearing) tail

6. What’s a Phospholipid Bilayer?
Two layers of phospholipids, with the hydrophobic (water fearing) tails pointing toward each other. That way, tails are protected from the watery environment inside and outside of the cell.

7. Questions? Plasma membranes consist of a ________ __________
Plasma membranes are semi- __________.
What can pass through a plasma membrane?

8. Diffusion
Diffusion is the movement of molecules from a region of high concentration to a region of low concentration by means of random molecular motion. Diffusion is the “desire” for all matter to be equally concentrated in it’s environment.
School bus example

9. Remember, molecules like to move from HIGH concentration to LOW concentration!

10. What’ll happen?

11. Equilibrium (both sides are equal)

12. Passive Transport in cells
Passive transport is when molecules simply move into a cell because there is a lower concentration of that molecule in the cell.
No energy needed!
Molecules move from HIGH concentration to LOW concentration…
Diffusion is a type of passive transport.

13. Active Transport in cells…
Active transport requires energy (in the form of ATP) to move molecules into and out of a cell.
Energy needed!
Energy is needed to move molecules from LOW concentration to HIGH concentration, opposite of Passive transport!

15. Active Transport (from LOW concentration to HIGH concentration, requires energy!)

16. Passive Diffusion animation ^_^

17. Questions?
Diffusion is the movement of molecules from a _____ concentration to a ______ concentration.
Does passive transport require energy?
Does active transport require energy?

18. More questions?
Passive transport is the movement of molecules from a ______ concentration to a _______ concentration.
Active transport is the movement of molecules from a ______ concentration to a _______ concentration.

19. Osmosis Lab for the next couple of days…(instructions 1 of 4)
Don’t worry about what osmosis is, we’ll cover it tomorrow.
STEPS:
Get a partner.
Get two plastic baggies.

20. Lab instructions (2 of 4) Label both baggies with:
Your name and your partner’s name
And salt water or regular water.
You’ll have one bag of each.
Get two or more potato slices.

21. Lab instructions (3 of 4)
Fill out observations about potato slices on worksheet.
Feel the firmness of the potato slice.
Is it firm?
Is it squishy?

22. Lab instructions (4 of 4)
In the bag labeled “salt water” mix salt and water until the solution is really, really salty.
In the bag labeled “regular water”, just pour regular water in it.
Place potato slices into bags.
Seal tight.

23. Have a good day!

24. OSMOSIS
Moving water…

25. OSMOSIS
Osmosis is the movement of a solvent (usually water) through a semi-permeable membrane to the highest solute concentration.
OSMOSIS IS ESSENTIAL FOR THE MOVEMENT OF WATER IN ANIMAL AND PLANT CELLS!!!!!!!!!!!!!!!!!!!!!!!

26. Water moves to the highest concentration of solute (can be salt, minerals, nutrients, sugar, etc.)
A solvent (like water) is any medium that can dissolve and hold a solute (like salt).
In a salt water mixture, the water would be the solvent, and the solute would be the salt.
In other words, water moves to the higher concentration of solute (like salt).

27. So if purple dots are salt…
REMEMBER that water (the solvent) tries to dissolve the salt (the solute).
Water moves to wherever the highest salt concentration is.

28. Movement of water to an area of more solute (purple dots = salt, minerals, nutrients, etc.)

29. Osmosis Animation

30. Hypotonic solutions
Hypotonic (hypo=less) solution – a solution that has a lower concentration of solute outside of the cell, and a higher concentration of solute inside the cell.

31. Isotonic solutions
Isotonic (iso=same) solution – a solution that has the same concentration of solute inside and outside of the cell.

32. Hypertonic solutions
Hypertonic (hyper=more) solution – a solution that has a higher concentration of solute outside of the cell, and a lower concentration of solute inside the cell.

34. Plant cell and osmosis

35. Questions?
In a solution of salt water, water would be the (solvent or solute) and salt would be the (solvent or solute)?
Osmosis is the movement of a solvent from a (low or high) solute concentration to a (low or high) solute concentration.

36. Food for thought…

37. Question 1 – group 1
Explain (in terms of osmosis) why a plant wilts if it isn’t given water.
Hint: The soil has a lot of nutrients and minerals.

38. Question 2
Suppose Hannah Montana is drifting at sea, on a life-raft. She is thirsty and severely dehydrated, but does not have fresh water. Why would it be dangerous to drink the salt water? What would one expect to happen? Put your answer in terms of osmosis.
Hint: The average human adult male body contains approx. 60% water.

39. Question 3
Why do marine invertebrates from salt water environments like shrimp, lobster and crab taste salty?
Hint: The ocean is salty. HIGH salt environment.
Another hint: What might happen if a lobster were to have a low salt concentration inside and high salt concentration outside?

40. The second hint…

41. RECAP
The plasma membrane of plant and animal cells consist of a phospholipid bilayer.
This bilayer is semi-permeable (some things can enter, others can’t).

42. RECAP Molecules move from HIGH concentration to LOW concentration.
This is called diffusion.
This is also a type of passive transport (doesn’t require energy).

43. RECAP
Active transport moves molecules from LOW concentration to HIGH concentration.
This requires energy.

44. RECAP
Osmosis is the movement of a solvent (like water) to a high concentration of solute (like salt).

45. RECAP Hypotonic solution – low solute environment
Isotonic solution – same concentration
Hypertonic solution – high solute environment