1. Movement through a Membrane- Passive Transport
No energy required

2. Due to pore size! And Molecule Size!
Membranes
3 Types
Permeable
Anything can move through
Impermeable
Nothing can move through
Semi permeable
Some can move through, some cannot
Due to pore size!
And Molecule Size!

3. Which is high concentration and which is low?
Low Concentration
= a molecule

4. How things get in? Diffusion:
the tendency of molecules to move from areas of high concentration to areas of low concentration (across cell membrane)
Concentration: how many molecules are in a given space

5. Which direction will the molecules move?

6. This random motion results in predictable movement
The molecules always move from areas of…
to areas of…
High Concentration
Low Concentration

7. What causes diffusion? Molecules move all the time! Motion is random
Molecules run into each other  move to where there are less molecules
This process requires no energy
Think: if keep packing people into the room, door opens, where will people try to go?

8. Osmosis
High
Movement of water from concentration to concentration (across cell membrane).
Movement of anything else?
Low

9. Effects Cell 3 Ways Same Concentration
Hypertonic Solution: Water moving out of cell. Cell getting?
Hypotonic Solution: Water moving into the cell. Cell getting?
Isotonic Solution: Water not moving. Why? Cell size?
Smaller
Larger
Same
Same Concentration

10. Osmosis and Cell function
Type
Description
How impact cell size?
Isotonic
Same on both sides
Cell stays the same
Hypertonic
Water moving out
Cell shrinks (gets smaller)
Hypotonic
Water moving in
Cell gets larger, can Lyse (explode)

11. Facilitated Diffusion
Passive Transport
Molecule is too big to move on own, so a carrier protein assists
Think of it kind of like an elevator – helps you move

12. Movement through a Membrane- Active Transport
Requires Energy

13. Think…..
What about when we need a lot of a substance? Need more glucose, need a lot of energy. Already higher concentration inside the cell than outside? How get in?
Active Transport!!!!
Requires Energy because….
Going across the concentration gradient!
Moving from Low to High Concentration

14. Types of Active Transport…
Endocytosis
Exocytosis
Example: Sodium-Potassium Pump
Entering cell
Exiting cell
How Messages are sent to the brain!