1. Diffusion, Osmosis and Active transport
Homeostasis

2. Table of Contents 1. Enzyme Notes
2. Enzyme lab pre & post questions (2 stamps)
3. Catalase lab data collection and rough draft
4. Notes on Enzyme Activity
5. Notes on Transport (p ) and class notes
6. Tape-In Cell membrane exploration.
7. Tape-In Keeping a balance
8. Tape-In Diffusion and Osmosis
9. Carrot Lab observations and data
10. Tape-In Solutions (Stamp)
11. Tape-In In –n- Out
12. Carrot Lab (4 stamps)
13. Osmosis Analysis Quiz (Stamp)
14. Rate “Per”fection page 1
15. Active Transport notes and WS (stamp)

3. Cellular Transport Unit
Passive Transport = movement of substances across the cell membrane without any input of energy by the cell

4. Passive Transport

5. Types
Diffusion = movement of molecules from high to low [ ] (concentration)
- driven by the concentration gradient
- spreads out evenly till dynamic equilibrium is reached
This Movement is the result of Kinetic Energy of the molecules

6. Diffusion

8. 2) Osmosis = diffusion of water
A solution may be one of the following: (compared to a cell)
- isotonic solution: same [ ] of water and solute
- hypotonic solution: lower [ ] of solute, a lot of water
- hypertonic solution: higher [ ] of solute, less water

9. Isotonic Solution (Red Blood Cells)
A solution is isotonic to a cell if it has the same concentration of solutes as the cell. Equal amounts of water enter and exit the cell, so its size stays constant.

10. Hypotonic Solution (Red Blood Cells)
A hypotonic solution has fewer solutes than a cell. Overall, more water enters a cell in a hypotonic solution, causing the cell to expand and even burst.

11. Hypertonic Solution (Red Blood Cells)
A hypertonic solution has more solutes than a cell. Overall, more water exits a cell in a hypertonic solution, causing the cell to shrivel and even die

12. ** Water tends to diffuse from hypotonic to hypertonic
Direction of Osmosis
Outside the Cell Inside the Cell Net Movement of Water
Isotonic Isotonic None
Hypotonic Hypertonic Inside the Cell
Hypertonic Hypotonic Outside the Cell
** If the solution outside the cell is hypotonic, then inside the cell is hypertonic and vice versa
** Water tends to diffuse from hypotonic to hypertonic

13. - Plasmolysis = cells shrink when turgor pressure is lost
- the reason plants wilt

14. - Cytolysis = cell bursts due to water entering the cell

16. How do freshwater organisms deal with osmosis?
What would be the problem?
Water would diffuse into the cells
What would organisms do to deal with the problem?
Pump water out or excrete large amounts of water

17. How do marine organisms deal with osmosis?
What would be the problem?
Water would diffuse out of the cells
What would organisms do to deal with the problem?
Pump water in or excrete large amounts of salt into their tissues

18. How do they do this? Contractile Vacuole!
Full
Empty

19. Contractile Vacuole in action

20. 3) Facilitated Diffusion
= move molecules across the cell membrane through carrier/transport proteins
- are specific for the type of molecule they help diffuse

21. Facilitated Diffusion (Open Channels)

22. Facilitated Diffusion (Proteins Change Shape)

23. Diffusion vs. Facilitated Diffusion
Diffusion Facilitated Diffusion

24. Overview Passive Transport Active Transport Diffusion Osmosis
Facilitated Diffusion
Active Transport
Protein Pump
Bulk Transport
Endocytosis
Pinocytosis
Phagocytosis
Exocytosis

25. Active Transport = substances can cross the cell membrane with an input of energy from the cell
The movement of molecules is AGAINST the concentration gradient. ( From low concentration to high concentration)

26. Active Transport

27. 1) Endocytosis = the process by which cells ingest “stuff”
- vesicle holds the “stuff”
- two types:
1) pinocytosis - solutes and fluids
2) phagocytosis - large particles or whole cells

28. Endocytosis
Vesicle

29. 2) Exocytosis = the process by which cells release “stuff”
- is essentially the reverse of endocytosis

30. Exocytosis
Vesicle

31. ACTIVE TRANSPORT – requires energy input (ATP)
Protein Pumps
Bulk Transport
Endocytosis – two types: phagocytosis and pinocytosis
Exocytosis
Animation
Another animation

32. HOMEOSTASIS AND TRANSPORT
             
  I. Cell Membranes
Cell membranes help organisms maintain homeostasis by controlling what substances may enter or leave cells
B. Some substances can cross the cell membrane without any input of energy by the cell
C. The movement of such substances across the membrane is known as passive transport
D. To stay alive, a cell must exchange materials such as food, water, & wastes with its environment
E. These materials must cross the cell or plasma membrane
                                                                                                

33. F. Small molecules like water, oxygen, & carbon dioxide can move in and out freely
G. Large molecules like proteins & carbohydrates cannot move easily across the plasma membrane
H. The Cell Membrane is semipermeable or selectively permeable only allowing certain molecules to pass through

34. II. Diffusion A. Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration

35. B. Small molecules can pass through the cell membrane by a process called diffusion C. Diffusion across a membrane is a type of passive transport because it does not require energy

36. D. This difference in the concentration of molecules across a membrane is called a concentration gradient
E. Kinetic energy keeps molecules in constant motion causing the molecules to move randomly away from each other in a liquid or a gas

37. The rate of diffusion depends on temperature, size of the molecules, & type of molecules diffusing
H. Molecules diffuse faster at higher temperatures than at lower temperatures
I. Smaller molecules diffuse faster than larger molecules

38. J. Most short-distance transport of materials in and out of cells occurs by diffusion
K. Solutions have two parts --- the solute which is being dissolved in the solvent
L. Water serves as the main solvent in living things

39. M. Diffusion always occurs down a concentration gradient (water moves from an area where it is more concentrated to an area where it is less concentrated)

40. N. Diffusion continues until the concentration of the molecules is the same on both sides of a membrane
O. When a concentration gradient no longer exists, equilibrium has been reached but molecules will continue to move equally back & forth across a membrane

42. Osmosis Think back to solutions: solutes and solvents
Osmosis is the process by which water molecules diffuse across a cell membrane from an area of lower solute concentration to an area of higher solute concentration.
Direction of movement depends on relative concentrations of solutions.

43. Direction of movement into cells
Hypotonic to the cytosol
solution outside the cell is less concentrated than inside the cell
water moves into the cell
Hypertonic to the cytosol
solution outside the cell is more concentrated than inside the cell
water moves out of the cell
Isotonic
concentrations are equal

44. Red blood cells are placed into 3 different types of solutions: figure out the types of solution in the beakers by looking at the RBC
HYPOTONIC
ISOTONIC
HYPERTONIC

45. How do freshwater organisms deal with osmosis?
What would be the problem?
Water would diffuse into the cells
What would organisms do to deal with the problem?
Pump water out or excrete large amounts of water

46. How do marine organisms deal with osmosis?
What would be the problem?
Water would diffuse out of the cells
What would organisms do to deal with the problem?
Pump water in or excrete large amounts of salt into their tissues

47. How do they do this? Contractile Vacuole!

48. Finish the statements Diffusion is… Osmosis is…
A hypertonic solution has…
A hypotonic solution has…
A cell placed in a hypertonic solution will…
A cell placed in a hypotonic solution will…
Both osmosis and diffusion are _______ transport because they do not require _______.

49. Passive Transport – no energy input required
Diffusion
Osmosis
Facilitated Diffusion

50. Carrot Lab Advice
Your goal is to experimentally find the best isotonic solution for carrots.
How? set up 4-5 baggies with carrots and different concentrations of salt solutions to leave over night.
You will have to figure out what the appropriate solutions should be and..
how to properly make those solutions.

51. Some Lab tips
Dab your carrot with a paper towel before you weigh it so you are not weighing the excess water.
Be sure to use the electronic balance appropriately otherwise you will get incorrect data.
Be meticulous about recording all materials, procedures and data collected.

52. Using and electronic balance

53. Today: (Thu/Fri) Tape-In and Check page 3/Procedures
How good am I at writing procedures?
Decide how much salt and how much water you will put in each baggie
Calculate the percent solution for each baggie
Revise carrot lab procedures
Set up baggies and label

54. Hypothetical Carrot Lab Data
Change in mass
Percent Silinity 0%
0.25%
0.5%
0.75% 1%
0.35 g
0.16g
-0.02g
-0.26g
-0.40g

56. Facilitated diffusion
Carrier Proteins: located in membrane * Channels (always open) * Gated channels (open when needed)

57. ACTIVE TRANSPORT – requires energy input (ATP)
Protein Pumps
Bulk Transport
Endocytosis – two types: phagocytosis and pinocytosis
Exocytosis

58. Active transport – Protein pumps