1. Diffusion & Active Transport

2. Review of cell membrane
Controls what gets in and out of the cell.
Semipermeable.

3. Concentration Amount of a substance compared to water
High Concentration = A LOT of substance
Low Concentration = SMALL amount of substance

4. High  Low Concentration
diffusion
Diffusion
Does not use energy.
Smaller molecules.
High  Low Concentration
Molecules move from areas where there is A LOT of the substance to areas where there is LESS of it.
Examples: Water, Glucose, Oxygen, Carbon Dioxide, Iodine

5. diffusion

6. Low  High Concentration
Active transport
Active Transport
Uses energy.
Larger molecules.
Low  High Concentration
Molecules are very large and need the help of energy (ATP) to move across membrane.
Move from areas where there is a SMALL AMOUNT of a substance to areas where there is MORE of it.
Examples: Starch

7. Active transport

8. Diffusion Active Transport Two types of Transport Does not use energy.
Smaller molecules.
High  Low Concentration
Active Transport
Uses energy.
Larger molecules.
Low  High Concentration
Brainpop

9. Diffusion of water
If the amounts are not equal, but molecule is too large to pass through the membrane, WATER WILL DIFFUSE THROUGH THE MEMBRANE.

10. Osmosis: The Diffusion of water Animation
Large
Molecules

11. Osmosis: the Diffusion of water

12. Cells have some salt in them
Place cell in pure, “distilled” water
 WATER WILL ENTER THE CELL
Place cell in salt water
 WATER WILL LEAVE THE CELL

13. Water Diffuses into Cell
Animation
No diffusion of water
Water Diffuses into Cell
Water Diffuses out of Cell