1. The movement of materials in and out of cells Ch 8
Cellular Transport
The movement of materials in and out of cells
Ch 8

2. Cellular Transport What substances move ? How do they move?
What is the membrane structure?
What is passive versus active transport?

3. Solution Concentration:
Like density =
# molecules per
volume of container
Low or High Concentration
* * * * *
* * * * * * * * * * * * * * *
High Conc.
* *
Low Conc.

4. Diffusion Movement of molecules: gas or liquid Law of Diffusion:
From High Concentration to
Low Concentration

5. Diffusion of gases……. O2
High
CO2
CO2
High

6. Cell Membrane Surrounds cells Gives shape to animal cells
Inside cell wall of plant cells

7. Cell Membrane
Made of:
Lipid layer
Protein channels
Semi-permeable

8. Cell Membrane

9. Semi-permeable: Semi= “some” substances may pass Selective
Based upon size & solubility
H20 flows
Salt remains

10. Osmosis Movement of water Across a semi-permeable membrane
Special case of diffusion

11. Equilibrium H2O H2O H2O On both sides of membrane Osmosis stops
“Equi” =Equal concentrations
On both sides of membrane
Osmosis stops
Isotonic Solution

12. In Osmosis….only H2O moves
Therefore focus on the water concentration:
1% Salt solution
Water is
High concentration
Salt is Low
10% Salt Solution
Water is
Low
concentration
Salt is High

13. Osmosis in cells 10% salt solution -H20 +NaCl 1% salt solution + H20
Water flows from High to Low Concentration

14. Active or Passive Transport?
Which requires ATP energy?
Which goes with the concentration gradient?
Which goes against the gradient?

15. Concentration Gradient
* *
* * * *

16. Passive Transport Diffusion or Osmosis Going with the gradient
No ATP energy required
High Conc. To Low Conc.
* * * * * * * * * *

17. Active Transport Against the gradient Requires ATP
Low to High Concentrations
Salt returning to blood in kidneys
* * * * * * * * * * *

18. Plasmolysis Cell membranes shrink or expand
Dependent on salt concen-trations

19. Hypotonic or Hypertonic Solutions?
Tap
Water
Hypotonic = “under” or low salt outside, relative to cell
Hypertonic = “over” or high salt relative to cell
Salt water
inside cell

20. Sea water organism in fresh water……………….
Tap
Water
Hypotonic Solution =
Low salt concentration outside the cell
High Water concentration outside
Water moves?
Inside
Cell Bursts!
Salt Water
Inside Cell
Low Water
H20

21. Fresh water organism in salt water………….
Hypertonic Solution
Water moves?
Out of the cell
Cell shrinks
Salt Water
High salt
Low water
Fresh water
Inside cell=
High Water
H20

22. Plants cells bulge, not burst!
Or Cell Membranes Shrink

23. Paramecium have water pumps! (called contractile vacuoles)