1. Do Now 11/7
OBJECTIVES: 1. define osmosis, diffusion, facilitated diffusion, passive transport, concentration gradient, equilibrium, and dynamic equilibrium.
 2. predict the flow of water and solute molecules across semipermeable membranes, and describe how these processes affect living cells.
TASK: 
HW check ; 2. The cells of plant seeds store oils in the form of droplets enclosed by membranes. These membranes are very different from the cell membrane even though they are made of the same phospholipids.
Draw a simple model for a membrane around an oil droplet, and briefly explain why this arrangement is more stable than bilayer.

2. hydrophilic
Since the oil is hydrophobic, this membrane has only ONE LAYER. Polar head groups on the outside, hydrophobic tails in the oil
hydrophobic

3. A Quick Demonstration…

4. How is this picture of outer space similar to the demonstration?

5. Diffusion!
Hot
Water
Cold
Water

6. Passive Transport
Passive transport is the movement of molecules from areas of high concentration to areas of lower concentration. It happens spontaneously (spontaneous = requires no addition of energy)

7. It’s the same for stardust and molecules!
Diffusion: The movement of particles from an area of high concentration to lower concentration.
It’s caused by the random motion of particles (aka thermal energy)
When the concentration of particles becomes equal in all parts of the environment, that’s called equilibrium.

8. Equilibrium
When the concentration of solute is equal throughout a solution.

9. Dynamic Equilibrium
Dynamic equilibrium refers to a state where the overall conditions don’t change, but individual parts keep moving
Example: 5 molecules move in, 5 molecules move out, still at equilibrium.

10. Diffusion: A type of passive transport
Passive transport is the movement of matter into or out of a cell WITHOUT the use of energy by the cell.
Diffusion across the cell membrane is how small molecules get into and out of cells.

11. Concentration Gradient
A concentration gradient is a difference in concentration across a space.
Going “down” the concentration gradient means moving from an area of high concentration to low
High Concentration
Low Concentration
“down” the gradient 

12. How your cells get O2 and get rid of CO2

13. Diffusion: why flatworms are flat !
Since they have no respiratory system, planarians like this have a flattened body plan to allow for fast diffusion of oxygen and carbon dioxide to all their cells.

14. Do Now 11/18 OBJECTIVE: Complete previous. TASK:
2. For each word pair in parentheses, select the correct word.
In diffusion, (solute / solvent) molecules move (up / down) their concentration gradients, from areas of (higher / lower) concentration to areas of (higher / lower) concentration.

15. Osmosis: The diffusion of water across a semi-permeable membrane

16. Things always move from areas of higher concentration to lower concentration spontaneously (passively)

17. Effects of Osmosis can be serious for a cell!
Hypotonic
Hypertonic
Isotonic
Water out
Of cell
No net change
Water into cell

18. SOLUTE SUCKS!
Water moves to where there is more solute.

19. Hypo Hypo Hippo

20. How cells cope

21. Osmosis & Plants

22. Plant Cells & Osmosis
Plasmolysis

23. Hypotonic environment
Causes turgor pressure.
Plant is healthy.
Hypertonic environment
Causes wilting.
Plant is unhealthy.
Plasmolysis

24. One Last Time

25. Facilitated Diffusion
Facilitated diffusion is like regular diffusion in that substances are moving from high concentration to low without the use of cell energy.
The difference is the solute molecules can’t get through the membrane alone, and travel through proteins instead.

26. Facilitated Diffusion
Membrane
Proteins
Solutes too big
Or too polar
To diffuse normally

27. Wrap Up / Key Ideas
Diffusion: The movement of solute molecules down a concentration gradient. Small molecules (e.g. H2O, O2, CO2) cross the cell membrane via diffusion
Osmosis: The diffusion of water across a semi-permeable membrane.
Facilitated Diffusion: The diffusion of large and/or polar molecules across the cell membrane through proteins.
Passive Transport: Movement of material into or out of a cell without the use of energy by the cell.
Concentration gradient: A difference in solute concentration across a space.

28. DO Now 11/17
Reverse osmosis is a process used to desalinate salt water to make it drinkable.
How might this process work? Sketch a design that uses a semi-permeable membrane to purify water.
Is this process passive or active? How do you know?

29. You Need Energy to Go Up a Concentration Gradient!
Fresh water out
Salt water at high pressure
Selective membrane prevents large solutes and ions from passing through.
They become MORE concentrated

30. Passive Transport Definition: Type 1 Type 3 Type 2 DIFFUSION OSMOSIS
The process of substances passing through the cell membrane WITHOUT ANY INPUT OF ENERGY BY THE CELL.
Passive Transport
Type 1
Type 3
Type 2
DIFFUSION
OSMOSIS
FACILITATED
DIFFUSION
Definition:
Solute molecules move from an area of high concentra-tion to an area of low conc. Powered by the random motion of molecules.
Key Term:
Equilibrium
Definition:
Cell uses carrier proteins in membrane to allow the diffusion of molecules that can’t pass through membrane alone.
Hypertonic:
Solute conc. Bigr
outside. H2O out
Definition:
Diffusion of water from an area of high H2O conc. (low solute conc.) to low (high solute conc.)
Required for
Ions
(charged
molecules)
Isotonic:
Solute conc. =
Inside & out.
No net H2O
change.
And
Hypotonic:
Solute conc. Lower outside.
H2O in. Hypo-Hippo
Large
Molecules

31. Read All About it!
Section 5-1 “Diffusion” pp
SR #1, p. 100.