1. How do molecules move around?
Diffusion is the movement of molecules from a HIGH concentration
to a low concentration

2. Whaddaya mean, molecules MOVE ?????
You gotta be kidding me!
Yeah, right
diffusion animation

3. OSMOSIS WATER through a membrane Osmosis is the movement of
from a high to a low concentration
through a membrane

4. To go into or out of a cell by diffusion or osmosis (without using energy)
A molecule must be . . .
The right size to pass through an opening
The right shape to pass through an opening
Going from a high to a low concentration

5. Cell membranes must have
Small openings for small molecules
Medium openings for
medium molecules
And the BIG stuff is a whole other story!!

6. SMALL openings in between phospholipids for small molecules:
Examples:
Water
Oxygen
Carbon dioxide
Alcohol

7. Medium Protein Doorways for medium sized molecules
Examples:
Glucose
Amino Acids
Some Lipids
Some Starches

8. Passive Transport
Materials moving into or out of the cell without using any energy
Examples:
Diffusion
Osmosis
Open protein doorways (channels)

9. Active Transport
Needed for molecules going from a low to high concentration (reverse diffusion)
Needed for LARGE molecules
Active = uses up ENERGY (ATP)

10. Active transport from a low to a high concentration – ENERGY

12. The BIG stuff Endocytosis Exocytosis
Membrane surrounds particle to form a vesicle which then moves INTO the cell
Exocytosis
Vesicle surrounds particle and moves to membrane and OUT of the cell

14. The cell membrane is “selectively permeable”. =
It controls what enters and leaves the cell.

15. The Cell Membrane PLUS