1. TP:SWBAT understand how nutrients and wastes are exchanged between cells? Do Now: Define Homeostasis. Explain how the cell membrane helps a cell maintain homeostasis.

2. There are two types of transport…
Passive transport
Active transport

3. Passive Transport:
Does NOT require any ENERGY to move materials through the cell membrane.
Materials will pass through on their own if they are small enough to fit through.
And if the molecules move with the concentration gradient (going from a higher to a lower concentration).

4. Passive Transport

5. Concentration Gradient:
Materials will continue to move into the cell until there is a balance both inside and outside.
This balance is called Dynamic Equilibrium

6. There are 2 types of Passive Transport:
Diffusion
Osmosis

7. Diffusion is the net movement of a substance (liquid or gas) from an area of higher concentration to an area of lower concentration.
Scenario: You enter the girls or boys bathroom.
An obnoxious fellow student lights a stink bomb after entering one of the stalls.
Disliking the smell you go to the farthest stall you can.
But the smell creeps up on you!
This is an example of diffusion in action.

9. Diffusion Does NOT require any energy
Particles move from a higher concentration to a lower concentration
Diffusion spreads the particles evenly until Dynamic Equilibrium is reached

10. Diffusion

11. Low
High

12. Diffusion of a dye in a beaker of water
The overall (or net) movement is from high to low concentration. Eventually, if no energy is input into the system the molecules will reach a state of equilibrium where they will be distributed equally throughout the system.
Diffusion of a dye in a beaker of water

13. Osmosis Does NOT require energy Specific to WATER only
Water will flow from a high concentration to a low concentration
In this case, water moves through root cells to give life to the plant

14. Osmosis

16. TP: SWBAT understand how the solutions impact diffusion.
Do Now: A common remedy used to relieve a sore throat (swollen throat tissue) is to gargle with salt water. Explain why this is helpful.

17. Solutes
Most liquids have dissolved particles floating in them called solutes.
These solutes take up space with water molecules

18. Solutes
A solution that contains very few dissolved non-water molecules is considered to have a very high concentration of water, because water makes up a high proportion of the molecules present.
Conversely, a solution that contains a high concentration of solutes is considered to have a relatively low concentration of water molecules.

19. Which solution has more solutes?
= salt
Salt Water
Tap Water

20. Slug Osmosis
Living cells are surrounded by a membrane that many substances cannot penetrate.
An example of such a substance is salt.
If salt is sprinkled on a slug, the salt increases the solute concentration in the water that lies on the outside of the animal's skin.

21. Poor Slugs
The salt (represented by the orange particles in the illustration) cannot penetrate the skin in significant amounts.
However, the difference in the concentration of water between the inside and outside of the cells results in osmosis.
Water (represented by the blue particles and arrows) rapidly leaves the animal's tissues, leading to death.

22. Osmosis in Humans
Humans are much better protected against water loss, because our skin cells are covered with a protein called keratin.
However, osmosis is still a life-and-death matter for us in other ways.
For example, the functioning of our kidneys relies heavily on osmosis.
Excessive salt in the diet is thought to be one factor promoting high blood pressure, because the salt goes into the fluids surrounding your cells and draws water out by osmosis.

23. There are 3 different types of Solutions:
Hypertonic (“viper”)
Hypotonic (“hippo”)
Isotonic (same)

24. Hypertonic Solution
The solution contains MORE SOLUTES (hyper) than water
Water moves out of the cell
The cell shrinks and dies
Hyper Viper
80% water
90% water

25. Solution Animations

26. Hypotonic Solution
Solution contains LESS SOLUTES (hypo) and MORE WATER
Water moves into the cell
Cell will swell and burst
Hypo hippo
90% Water
80% water

27. Solution Animations

28. Isotonic Solution
Solution contains the SAME amount of solutes and water
Under these conditions, water diffuses into and out of the cell at EQUAL RATES, so there is NO Net Movement of Water.

29. Solution Animations

30. Image showing what happens when a blood cell is in a hypotonic environment & a hypertonic environment

31. Image showing what happens when a plant cell is in a hypotonic environment & a hypertonic environment

32. Which side has more water?
= salt A B
membrane

33. Which side is Hypertonic?
= salt A B
membrane

34. Which way will the water move?
= salt A B
membrane

35. Task: Create a table comparing Hypertonic, Hypotonic and Isotonic.
Make sure to include what leads to each situation, how water will diffuse and the effect on the cell.

36. You are stranded on a desert island, with nothing but a cell phone
You are stranded on a desert island, with nothing but a cell phone. You know that help will arrive within a couple days, but you are dehydrated and need to quench your thirst. You are surrounded by the ocean on all sides; should you drink the salt water? Why or why not?
In the days before refrigeration, a common practice to preserve meat was to add a lot of salt to the meat. Why was this a relatively effective technique?
Design a procedure using osmosis and/or diffusion that will produce a shriveled cell. 36

37. If I put a Red blood cell in a hypotonic solution, what will happen to it?
Before
After

38. If I put a liver cell in a hypertonic solution, what will happen to it?
Before
After

39. TP: SWBAT understand when cell’s require energy for transport
Do Now: What kinds of solutions may lead to a cell’s death? Why would this happen?

40. Active Transport Low High
Cells MUST use their own energy (ATP) to move molecules AGAINST the concentration gradient
Here, molecules are moving from areas of LOW to areas of HIGH concentration
Low
High

41. Active Transport There are 2 types of active transport
1. Endocytosis (in)
2. Exocytosis (out)

42. ENdocytosis
During endocytosis, the cell membrane folds IN and forms a small pouch.
The pouch then pinches off from the cell membrane to become a vesicle.

43. There are actually 2 types of endocytosis:
Phagocytosis – when an entire cell is gobbled up. (Phago = BIG)
Pinocytosis – when external fluid is engulfed. (pino = small)

44. Pinocytosis
The cell “gulps” droplets of extracellular fluid (nutrients) and then forms a vacuole inside the cell in which the nutrients are distributed

45. Pinocytosis

46. Phagocytosis
When portions of the cell engulf prey or large chunks of matter flowing around them
Ex: white blood cells engulf bacteria

48. Phagocytosis

49. Of course this type of transport doesn’t go just one way…
We just talked about endocytosis, which is a process where cells take in material from the outside.
Do you think cells also send material outside?
YES!
This is process is called EXOcytosis

50. Exocytosis
Material from within the cell is transported to the cell membrane inside a vesicle
The vesicle attaches itself to the cell membrane
The cell membrane opens up to allow the materials to escape from the vesicle
The vesicle’s membrane becomes part of the outer cell membrane

52. Task Move to your learning style groups.
Each group must create a way of showing and explaining their assigned transport.
Some groups may choose to make a skit, sign, song, etc.

53. Task
1) As waste chemicals build up in a cell, homeostasis is threatened.  State how diffusion helps a cell maintain homeostasis.
2) Compare and contrast:  Diffusion and active transport are processes that are important to the cell maintenance of homeostasis in organisms.  Compare and contrast the two processes 53