1. Have your Cell Division packet on edge of desk! Thanks!
Learning Goal:1) I can explain the process of diffusion & osmosis and how it’s important to cells.
Thinking Skills:
Problem solving, main idea
Habits of Mind:
persisting
Have your Cell Division packet on edge of desk! Thanks!
Computers ON!
Agenda: Feb 13 , 2015
ET #51: Why do you smell odors when you are not necessarily right next to the source?
Review Cell Division
Explain 28: Osmosis Activity
4) Homework: Complete Osmosis HW? Test Review due Tuesday/ Wednesday after break. Test 2/26 & 2/27; SCaR-NONE

2. ET #51: Why do you smell odors when you are not necessarily right next to the source?
good ppt of osmosis/diffusion

3. Examples of diffusion

5. Scientifically speaking, what’s wrong with this Garfield picture?
Let’s quickly and quietly get a RED pen out and log on to the computer.
Go to the public/all/kmchenry folder and grade your Cell Division paper, making corrections as needed. You have SEVEN minutes! Work quickly!

6.
(difference btwn meiosis & Mitosis)
Aging

7. What is cancer? Out of control mitosis! 

8. EGGS prior to vinegar

9. What’s left on the outside?
#6. Egg Soaked in Vinegar
Vinegar causes egg shell (calcium carbonate) to disappear, layer by layer…
What’s left on the outside?
The membrane

10. EGG prior to and after vinegar

11. Before and After
What differences do you notice here?

12. Distilled Water before and after

13. 9. The egg in distilled water swelled up! Why?
Draw it!
9. The egg in distilled water swelled up! Why?
H2O
Protein/fats
Because water moved into the egg(high to low)
Expanded (swelled up)

14. After
#10
Before

15. One shell-less egg soaking in the vinegar was placed in syrup solution.
                                                                            The egg in the syrup shriveled up, water moved out of the egg. (hypertonic)

16. Red Dye Egg before and after
#11

17. 12. What is the “Big Idea” here?
Water moves into or out of the eggs depending on the concentration of water inside vs. outside.
= moves from High to Low

18. Saltwater is the solution, Salt is the solute Water is the solvent
Solute: “The dissolved substance in a solution”
Example: Saltwater
Saltwater is the solution,
Salt is the solute
Water is the solvent
Draw different solutes by using different symbols.
Example:
= water
= sugar
= salt

19. (Back page)Tap Water Egg before and after

20. (Back Page) Salt Water Egg before and after

23. Websites to visit to help:
#3a
Elodea Leaf (normal)

24. #6a

25. Elodea Leaf in 5% Salt solution

28. Passive Example 2: Osmosis (H2O movement through membranes)

29. ET #47: Show and explain the difference between PASSIVE transport & ACTIVE transport. **passive-no energy required-example: Diffusion

30. Active-goes against the gradient-from low to HIGH. Needs energy!
Dialysis in the kidneys-ACTIVE transport for Sodium ions

31. Diffusion- simple “high to low” movement.

33. One solution has a lower concentration of solute than another.
Both solutions have same concentrations of solute.
One solution has a higher concentration of solute than another.

34. There are microscopic pores in the membrane.5
There are microscopic pores in the membrane.
Molecules below a certain size can diffuse
through the pores.
Water molecules can easily diffuse through
the pores.
In the next slides
represents a water molecule
and
represents a sugar molecule

35. membrane water sugar solution 6
There are as many water molecules on the right as there are on the left but many of them are attached to sugar molecules and are not free to move.

36. Because there are more freely moving water molecules on 7
Sugar molecules can pass through the membrane but, being surrounded by a cloud of water molecules, they move more slowly.
Because there are more freely moving water molecules on
the left, more diffuse through the pores of the membrane from
left to right than from right to left.
Molecular movement

37. 8
Animation

38. Because the membrane allows only molecules 9
Because the membrane allows only molecules
of a certain size to diffuse through it, it is
called selectively permeable.
The cell membrane functions as a selectively
permeable membrane.
The cell sap and cytoplasm function as
fairly concentrated solutions.

39. The scale of the following drawings is greatly distorted.
Scale of drawings 10
The scale of the following drawings is greatly distorted.
Even if the cells were as large as they appear on the screen, the molecules would still be invisible particles

40. Osmosis in animal cells11
so water diffuses into the cell
by osmosis
There is a greater concentration of free water molecules outside the cell than inside
and the cell swells up

41. If osmosis continued the animal cell would burst12
If osmosis continued the animal cell would
burst
This would be bad news for animals
Consequently there are processes in the
animal’s body which control osmosis
Mainly, this is done by keeping the
concentration of body fluids outside the cell
the same as it is inside

42. As a result the fish takes in water by osmosis
Fresh water fish 14
Trout
In fresh water fish, the blood is more concentrated than the surrounding water
As a result the fish takes in water by osmosis
Not so much through the skin, which is thick,
but through the gills which have a very thin
membrane

43. The fish gets rid of the excess water by means of its kidneys14
Perch
The fish gets rid of the excess water by means of its kidneys
kidneys expel
excess water ...
blood carries water
to kidneys
gills absorb water by osmosis
...in the form of
dilute urine
heart

44. Sea water is a more concentrated solution than the
Sea water fish 15
Herring
Sea water is a more concentrated solution than the
fish’s blood. What will be the osmotic effect ?
A sea water fish will lose water by osmosis through
its gills.
Sea water fish related to sharks, e.g. dogfish, avoid losing water to their surroundings by maintaining their blood at the same concentration as sea water
The fish drinks sea water and the gills expel the
excess salt from the blood, so keeping its
concentration constant

45. The vacuole will expand, pushing the cytoplasm16
In a plant cell, the cell membrane acts as a
selectively permeable membrane
The cell wall is freely permeable to water
The vacuole contains a solution of salts and sugars
If there is water outside the cell, it will diffuse
by osmosis into the vacuole
The vacuole will expand, pushing the cytoplasm
outwards against the cell wall

46. The cellulose cell wall cannot stretch, so the 17
The cellulose cell wall cannot stretch, so the
vacuole cannot continue to expand
But the pressure of the vacuole against the cell
wall makes the cell very firm
A plant cell in this condition is said to be turgid
If all the cells in the plant are turgid, the plant will
be firm and upright and the leaves would be
expanded

47. Plant cells cell wall vacuole cytoplasm and cell membrane18
cell wall
vacuole
cytoplasm and
cell membrane
A useful analogy is the bicycle tyre. The outer casing represents the cell wall; the inner tube represents the cytoplasm and the air inside represents the vacuole. When the tyre is pumped up, the air pressure pushes the inner tube against the outer casing. The outer casing cannot expand and so the pressure in the tube builds up until the tyre is firm
The cell absorbs water
by osmosis ....
....but the cell wall stops the
cell expanding any more

48. Limp and turgid tissue 21
These cells are short of water; the tissue is limp and the plant is wilting
The cells have taken up
water by osmosis; the
cells are turgid and the
tissue is firm

49. Busy Lizzie (1) wilting (2) recovering (3) recovered 22
(1) Wilting. The plant is short of water. The leaf cells are no longer turgid and the leaves curl up and droop.
(3) Recovered. Water is once more available. The leaf cells take up water by osmosis and become turgid. The leaves are now firm and are held horizontally.
Woody plants such as trees and shrubs do not collapse when they wilt but their leaves become limp.