1. Movement of molecules into and out of a cell
Cellular Transport
Movement of molecules into and out of a cell
Introduce with: paper towels…soak up water even if you just put a corner in water
Perfume sprayed in one area…moves out to rest of area

2. Facts you should already know
All particles are in constant random motion (KINETIC ENERGY)
Particle in a solid move very slowly
Gas particles move faster; liquids in between

3. Types of Cellular Transport
Passive: requires no energy (ATP)
Active: requires energy (ATP)

4. Three Forms of Transport Across the Membrane
The Plasma Membrane
12/8/2018
copyright cmassengale
G. Podgorski, Biol. 1010

5. 3 Types of Passive Transport

6. 1st type of Passive Transport: Diffusion
Individual particles move from an area of higher concentration to an area of lower concentration

7. Diffusion
Result of random movement of molecules

8. When the concentration of a substance is the same on one side of a membrane as it is on the other, the system is in balance--it has reached
equilibrium.

9. Always constant movement but there’s no net change
(concentration stays the same on both sides of the membrane)
Called:
Dynamic Equilibrium.
Key things to understand: constant motion
Equilibrium
Dynamic equilibrium

10. What affects diffusion?
Each lab group will be responsible for determining the effect of a different variable.
Size of molecules
Concentration of molecules
Temperature of molecules

11. Rate of Diffusion Affected by: Size of molecules Proof?
Concentration Gradient is the difference in concentration between two areas. The bigger the difference the faster diffusion will occur. Think of a ski slope and how fast you will go down.
Size of molecules: bigger molecules mover slower such as starch that doesn’t even go in; small molecules such as water, oxygen,and other non-polar molecules can get across. Slat usually doesn’t diffuse because it has a charge.
Temperature: the warmer it is the faster molecules move and that speeds up the random bouncing around of the molecules and thus diffusion.

12. Rate of Diffusion Affected by: Concentration of molecules
(also called concentration gradient)
Proof?

13. Rate of Diffusion
Affected by:
Temperature
Proof?

14. 2nd Type of Passive Transport: Osmosis
Special type of diffusion – only for WATER
Cells are 90% water
Movement of water molecules through a selectively permeable membrane
DOWN (with) concentration gradient
It is mostly water molecules that move in and out of a cell…that is why we have a special name for it.

15. Diffusion across a membrane Semipermeable membrane
The Plasma Membrane
12/8/2018
Osmosis
Diffusion across a membrane
Diffusion of water across a membrane
Moves from HIGH water potential (low solute) to LOW water potential (high solute)
Semipermeable membrane
G. Podgorski, Biol. 1010

16. Examples of Water Movement

17. selectively permeable membrane
Where is the greatest concentration of water?
Where is the greatest concentration of water?
70% water
30% salt
At the beginning water is more concentrated outside in the solution….therefore water will move into the bag until equilibrium is reached. At that point water molecules will continue to move …just at the same rate into and out of the bag.
100% distilled water
selectively permeable membrane

18. selectively permeable membrane
Water will into the cell.
70% water
30% salt
100% distilled water
selectively permeable membrane

19. selectively permeable membrane
What happens to the bag?
The bag swells.
If you put wilted flowers or a celery stalk in water, they will absorb the water and perk back up.
Same idea with dehydrated food…put in water and it swells up.
100% distilled water
selectively permeable membrane

20. selectively permeable membrane
Where is the greatest concentration of water?
90% water
10% salt
Water will flow out of the cell.
Salt does not flow through the selectively permeable membrane.
This causes cells to shrink. During hot summer when plants wilt this is what has happened. Leaving food out and it gets dry….
80% distilled water
selectively permeable membrane

21. 3rd Type of Passive Transport: Facilitated Diffusion
Movement of molecules that are too large to pass through a selectively permeable membrane
Uses transport proteins
Fast, specific, occurs with gradient
Think of this as an insect coming into a room thru a hole in a window screen.

22. Three Types of Solutions
describes amount of
solutes
Relative to inside of cell
Solution
Cell

23. Isotonic Solution
Concentration of dissolved substances is the same inside the cell as the solution it is in
Water molecules move…usually not the dissolved substances
These cells are in dynamic equilibrium.
No net gain or loss

24. Hypertonic Solution
Concentration of dissolved substances is higher inside the solution
(less water molecules outside)
If you call someone “hyper” they have too much energy! Hyper means more here also….A solution is hypertonic if it has more of the dissolved substance than the cell.
EX; a solution is 15% sugar and the cell is 1% sugar. There is more sugar in the solution…it is a hypertonic solution.
Now think of the water..the solution would have 85% water and the cell would be 99% water. Water will move out of the cell.
Water leaves the cell- this process is called Plasmolysis

25. Hypotonic Solution
Concentration of dissolved substances in the solution is lower than on the inside (more water molecules on outside)
Water will move into the cell to try to equalize the balance
(dissolved substances can’t move)
When you use the word solution  you are referring to what the cell is in.
EX: a solution has 1% salt ( and thus 99% water) and the cell is 5% salt and 95% water.
The solution has a lower concentration of salt…hypotonic solution.
Now look at the water concentration…water is higher on the outside in the solution and lower on the inside….water will move in…causing the cell to swell.
Cells swell up (“O” in hypotonic)
Pressure inside is called turgor pressure, good in plants, bad in animal cells

26. Slug Vacation Disasters

27. selectively permeable membrane
Water flows from the beaker into the bag.
70% water
30% salt
Salt does not flow through the selectively permeable membrane.
This is an example to test your understanding.
100% distilled water
selectively permeable membrane

28. selectively permeable membrane
What happens to the bag?
The bag swells.
This means the solution is
hypotonic.
100% distilled water
selectively permeable membrane

29. selectively permeable membrane
What happens to the bag?
90% water
10% salt
Example to test your understanding.
80% distilled water
selectively permeable membrane

30. selectively permeable membrane
What happens to the bag?
The bag shrinks.
This means the solution is
hypertonic.
80% distilled water
selectively permeable membrane

31. 3 Types of Solutions
Add to your “Incredible Egg” booklet the names of the solutions each egg was submerged in