1. Osmosis, Diffusion, and Facilitated Diffusion
Passive Transport
Osmosis, Diffusion, and Facilitated Diffusion

2. Homeostasis
The purpose of the cell membrane is to help the cell maintain homeostasis…
A constant internal condition
It allows the cell to control what enters and what leaves

3. Passive Transport Some molecules can easily cross the membrane
Water, oxygen and carbon dioxide

4. Three forms of Passive Transport
1. Diffusion—
Movement of molecules from high to low concentration
The difference in these areas is called the concentration gradient
Does not require energy
Rate depends on temperature, size and type of molecule
Faster at high temps, smaller, and short distance
Continues until even on both sides

5. Three forms of Passive Transport
2. Osmosis—
Movement of water
High to low concentration (less to more water)
Does not require energy
Will occur until equal

6. 3 types of osmotic solutions
Hypertonic Solution
Solute higher outside the cell
Water will diffuse out of the cell until equilibrium
Cells will shrink and die

7. 3 types of Osmotic Solutions
Hypotonic
Solute concentration is higher inside (less water)
Water moves into the cell until equal
Animal cells will swell and burst
Plants work best in this environment

8. 3 types of Osmotic Solutions
Isotonic
Concentration of solute same inside and outside
Water moves in and out freely
Animal cells work best

9. 3 forms of Passive Transport
3. Facilitated Diffusion
Faster than normal diffusion
No energy required
High to low concentration
Uses carrier proteins embedded in the membrane and channel proteins

10. The End 