1. Movement Through the Cell Membrane

2. Important Vocabulary
Concentration gradient: Difference in concentration from one location to another.
Equilibrium: both sides of the cell membrane have equal concentration.

3. Concentration Hypertonic: solution with a higher concentration.
Hypotonic: solution with a lower concentration.
Isotonic: solutions have equal concentration.

4. Permeability
Permeable: substance is able to pass through the membrane.
Impermeable: substance is not able to pass through.
Semipermeable: membrane is permeable to some substances, impermeable to others.

5. Is membrane permeable, selectively permeable, or impermeable?

6. Passive Transport Does NOT require energy.
Molecules move down a concentration gradient (high concentration to low concentration).
Types:
Diffusion
Osmosis
Facilitated Diffusion

7. Diffusion
Movement of molecules in a liquid or gas down a concentration gradient.

8. ? Osmosis Diffusion of water.
Ex. sugar water and membrane selectively permeable to water… what will happen? ?

9. Answer…

10. Facilitated Diffusion
Diffusion across a membrane using carrier proteins.

11. Factors that Increase the Rate of Diffusion
Hotter temperature
Higher concentration
Small particle size/increased surface area
Increase in pressure

12. Active Transport
Molecules are pumped from low to high concentration (against the concentration gradient).
Energy is required.

13. Endocytosis
Cell takes in liquids or large particles that are not able to move through the cell membrane.
Process:
1. membrane surrounds substance
2. Microfilaments pull membrane, pinches off
2. vesicle forms

14. Exocytosis
Opposite of endocytosis, substances are released from the cell.
1. cell forms a vesicle around substance.
2. vesicle is transported to cell membrane
3. vesicle fuses to cell membrane, contents released.

15. Application
Molecules that are soluble in lipids tend to move across cell membranes more quickly than those that are not. Why?