1. Pretest What is the job of the plasma membrane?
What is semi-permeable?
What is the difference between active transport and passive transport?
What is osmosis?
What will happen to a cell when placed in a hypertonic solution? Hypotonic solution?
What are examples of each?

2. It controls what goes into and out of the cell
The plasma membrane maintains homeostasis for the cell It is selectively permeable:
It controls what goes into and out of the cell

3. Two forms of transport across the membrane:
Passive Transport
No energy needed
WITH the gradient (high to low)
Examples:
Diffusion
Osmosis
Active Transport
ENERGY used
AGAINST the gradient
Examples:
Endocytosis
Exocytosis

5. Plasma Membrane Structure
Two key components of the membrane:
phospholipids
proteins

6. Crossing the Plasma Membrane: Passive Transport Energy. Direction
Crossing the Plasma Membrane: Passive Transport Energy? Direction? Examples?

7. Passive Transport: Diffusion
The phospholipids line up to form a double membrane
Small, uncharged particles are able to pass right between the phospholipids
This is called simple diffusion

8. Passive Transport: Diffusion
There are also proteins embedded between the phospholipids.
These proteins function as gates, allowing larger or charged molecules to get in/out of the cell
Only molecules which are “recognized” are allowed thru these proteins
This is facilitated diffusion

9. Passive transport: Diffusion
Concentration gradient:
Higher Concentration
Lower Concentration
Molecules collide – pass thru membrane

10. Passive Transport: Osmosis
The movement of water
Water moves TOWARDS the molecules
Think of it as “water wants to dissolve stuff”
Which way will water move in each case?

11. Passive Transport: Osmosis
HYPERtonic ISOtonic HYPOtonic

12. The effect of osmosis on animal cells
Cytolysis

13. What do plant cells have outside of the cell membrane that animal cells do not have? What difference will this make with osmosis?

14. Effect of osmosis on plant cells
Flaccid -
Turgid
due to plasmolysis
- cell shrinks from cell wall

15. Passive transport: osmosis
Which way will water move?

16. Hypertonic or Hypotonic?

17. Active Transport: Which direction? Energy Used? Examples?

18. Crossing the Plasma Membrane
Active transport
AGAINST the gradient
requires energy
Figure 3.8

19. Active Transport Endocytosis Exocytosis
Pino-
Phago-
Exocytosis
Ion pumps: Thru a protein, but using energy
Figure 3.9

20. Crossing the Plasma Membrane
Passive Transport
Active Transport

21. Crossing the Plasma Membrane
Passive Transport
No energy needed
WITH the gradient
Diffusion
Osmosis
Active Transport
ENERGY used
AGAINST the gradient
Can be through a protein
Endocytosis
Exocytosis

22. Post test What is the job of the plasma membrane?
What is semi-permeable?
What is the difference between active transport and passive transport?
What is osmosis?
What will happen to a cell when placed in a hypertonic solution? Hypotonic solution?
What are examples of each?