1. Packages and ships proteins Makes ATP from carbohydrates
QUIZ:
Which organelle:
Makes proteins
Packages and ships proteins
Makes ATP from carbohydrates
Define amphipathic.
Labels: A. B. C. D. E. A B C D E

2. Passive: osmosis, diffusion Active: endocytosis, exocytosis
Membrane Transport
Passive: osmosis, diffusion
Active: endocytosis, exocytosis

3. High Low Concentration gradient drives the NET movement of molecules
Molecules move randomly and continuously. Impacts change their direction.
High
Low
Concentration gradient drives the NET movement of molecules

4. Permeability

5. Osmosis
Movement of water across a membrane from high concentration to low concentration

6. Another rule of thumb:
The greater (steeper) the concentration gradient, the faster the rate of diffusion.
Cell A will diffuse faster
Cell A
Cell B
Concentration of solutes
Inside
Cell
Outside
Cell

7. Effect of temperature on diffusion Cell B will diffuse faster 38° 22°
Cell A
Cell B
Temperature °C
22°
38°
Cell A
Cell B

9. Active Transport
© Brooks/Cole - Thomson Learning

10. Sodium-potassium Pump
© Brooks/Cole - Thomson Learning

11. 3 factors that affect movement of molecules across membranes
Effect of Concentration: the greater the concentration difference across the membrane, the faster the rate of diffusion (agar blocks)
Effect of Temperature: the higher the temperature, the faster the rate of diffusion due to increased energy of solute molecules (agar blocks)
Effect of Pore Size: only solutes small enough to pass through the pores of a membrane are able to diffuse (dialysis: iodine moved in, glucose moved out, starch remained in)

12. Objective 3: Recognize the role of water potential in regulating the movement of water across membranes and note factors that affect water potential.
Objective 4: Describe the tonicity of biological solutions

13. Water potential: the potential energy of a volume of water; expressed as a pressure

14. Definitions Osmosis - the diffusion of water across membranes
Which way will the water go?

15. Definitions
Solute - the substance dissolved in a liquid (e.g., sugar, salt)
Solvent - the liquid in which the solute is dissolved (e.g., water)

16. “Free” water molecules can pass through membrane.
These solute molecules are too big to pass through membrane.
Lower water potential
Higher water potential

17. Obj. 4: Tonicity of solutions
Hypotonic - solution that contains FEWER solute particles than another solution
Hypertonic - solution that contains MORE solute particles than another solution

18. Rule of Thumb
The net movement of WATER is from hypotonic conditions to hypertonic conditions.
If two systems are equal in the number of dissolved particles, they are said to be isotonic and no net change in volumes will occur.
Hypotonic
Hypertonic

19. Notes on Diffusion and Osmosis
Both solutes and solvents (water) can diffuse across a membrane and the concentration difference will eventually equalize
We are interested in the period of time before the system equalizes (becomes isotonic), to observe which direction diffusion is occurring
Always pay attention to both solutes and solvents in a question - both may be important!

20. Objective 5: Recognize the role of the cell wall and of the vacuole in producing turgor pressure to maintain the shape of the plant cell.

21. Distilled water
HIGH turgor pressure
Salt water
LOW turgor pressure

22. Plant cells ONLY Cell and cell wall do not change size.
Vacuole swells and shrinks.
The pressure that develops between the cell wall and vacuole is called TURGOR pressure.

23. Egg in
Distilled water
Egg in
Sugar water
H2O
H2O

24. Water moves from hypotonic conditions to hypertonic conditions.
Water is hypOtonic
Egg is hypERtonic
Water is hypERtonic
Egg is hypOtonic
Distilled water
Sugar water
H2O
H2O

25. Discussion questions
Many hospital patients receive intravenous liquids to replace body fluids. These liquids are generally complex solutions of salts and sugars. If all the patient needs is fluid, why doesn’t the physician simply inject pure water?
Why can’t we drink salt water?

26. Dialysis tubing is a model for a cell membrane.
Starch & glucose
Iodine solution

27. Cells have a selectively permeable membrane
Dialysis tubing is a model for a cell membrane.
Iodine + starch=blue
Cells have a selectively permeable membrane
Starch & glucose
Iodine
Glucose
Iodine solution

28. Predict the effects of temperature and concentration gradients on diffusion rates

29. Concentration gradients
Sodium hydroxide solution 5%
0.5%
Agar Blocks
Started with 0%, diffused 5%
Started with 0%, diffused 0.5%
= 0.5
5 - 0 = 5
Much greater concentration gradient