1. Do Now:

2. The “bouncer” of the cell
The Cell Membrane
The “bouncer” of the cell

3. The Cell Membrane – (Plasma Membrane)
The barrier of the Cell

4. Functions (Jobs) of The Cell Membrane
Separates cell from outside environment
Protective barrier
Regulates movement in & out of cell Ex. Windows Screen in spring

5. Selectively Permeable Membrane
Selectively permeable: Only certain molecules can pass through
Small molecules move through easily
Ex: O2, CO2, H2O

6. Selectively Permeable Membrane
Large molecules can NOT move through
Ex: starch
SIMPLE SUGARS
STARCH

7. Transport: movement of materials across the membrane
Three types of transport:
Constant, free movement of small molecules ( glucose, O2, CO2 )
Free movement of water
Movement that requires energy (ATP): things that are forced through membrane

8. What happens when you spray air freshener?
11/30/08
What happens when you spray air freshener?

9. 11/30/08
First type: Diffusion
Diffusion: Molecules move freely from where there’s the most, to where there’s the least of them

10. Passive: doesn’t require energy, happens freely
11/30/08
Diffusion is passive
Passive: doesn’t require energy, happens freely 10

11. 11/30/08
Diffusion of Liquids 11

12. Which way will the glucose move?
11/30/08
Which way will the glucose move?
Equilibrium
Molecules will move until there’s an equal amount on both sides- called equilibrium 12

13. Concentration: how densely packed something is
11/30/08
Concentration: how densely packed something is
Example
Low concentration: loosely packed
High concentration:
tightly packed

14. Concentration: how tightly packed the molecules are
11/30/08
Concentration: how tightly packed the molecules are
Example
Low concentration: a little sugar dissolved
High concentration:
a LOT of sugar dissolved

15. Which side is high concentration?
11/30/08
Which side is high concentration?
High Concentration
Low Concentration A) B)
A) More tightly packed

16. Diffusion across a membrane Semipermeable membrane
11/30/08
What is Osmosis?
Diffusion across a membrane
Diffusion of water across a membrane
Moves from HIGH water concentration to LOW water concentration
Semipermeable membrane 16

17. Diffusion of H2O Across A Membrane
11/30/08
Diffusion of H2O Across A Membrane
High H2O concentration
Low H2O concentration
Which way will water move? When is equilibrium reached?

18. Where will water move? CELL 10 Glucose 90 H2O IN to the CELL
11/30/08
Where will water move?
10 Glucose 90 H2O
IN to the CELL
CELL
20 Glucose
80 H2O

19. Where will water move? CELL 90 Glucose 10 H2O Out of the CELL
11/30/08
Where will water move?
90 Glucose 10 H2O
CELL
Out of the CELL
80 Glucose
20 H2O

20. Where will water move? CELL 10 Glucose 90 H2O 10 GLucose 90 H2O
11/30/08
Where will water move?
CELL
10 Glucose 90 H2O
10 GLucose
90 H2O
The water is already balanced!
equilibrium
The cell is at _______________.

21. What happens when you pour salt on a slug?? 
The slug’s cells dehydrate and this kills the slug

22. Why does popcorn make us thirsty??
Mouth Cell
WATER
Huge popcorn =A big scam
Makes you super thirsty!
SALT

23. More Water outside, water moves in More water inside, water moves out
11/30/08
Dots = salt
More Water outside, water moves in
More water inside, water moves out
Equal amount of water
NO NET MOVEMENT OF H2O (equal amounts entering & leaving)
(Cell Swells)
(shrinking of a cell)
Water moves towards where the most dots are 23

24. Osmosis in Red Blood Cells
11/30/08
Osmosis in Red Blood Cells
Which way did the water move? 24

25. Which way did the water move?
11/30/08 25

26. Transport helps to maintain Homeostasis
Homeostasis: A balanced, steady state
Does this by controlling what enters & leaves the cell

27. Last type of transport: Active transport
Molecules move from where there’s the least to where there’s the most
(the opposite of diffusion)
Requires ATP!

28. Diffusion vs. Active Transport
-High to Low concentration
-Low to High concentration
-Uses ATP

29. 11/30/08
Exit card...
Many poisons work by inhibiting ATP production. Which type of transport would be most affected?
a. osmosis
b. diffusion
c. active transport

30. Is diffusion an active or passive process? Does it use energy?
11/30/08
Lets Review…
Define Diffusion
Is diffusion an active or passive process? Does it use energy?
How is active transport different from passive transport?
True or False: Osmosis is a type of diffusion 30

31. Describe what is happening:
11/30/08
Describe what is happening: