1. Chapter 3.4 Diffusion and Osmosis

2. Chapter 3.4 Diffusion and Osmosis
Objectives
Describe passive transport
Distinguish between osmosis, diffusion and facilitated transport.
You will accomplish this by taking notes, completing a foldable and drawing examples.

3. 3.4 KEY CONCEPT: Materials move across membranes because of concentration differences.

4. Diffusion and Osmosis are types of Passive Transport
Passive Transport is the movement of molecules across a cell membrane without energy input from the cell.

5. Require NO ENERGY from the cell
PASSIVE TRANSPORT
Require NO ENERGY from the cell
Molecules move from HIGH to LOW CONCENTRATION
Molecules move DOWN THE CONCENTRATION GRADIENT
3 types of Passive Transport
- DIFFUSION
- OSMOSIS
- FACILITATED TRANSPORT

6. Molecules diffuse down their concentration gradient.
Concentration Gradient: The difference in the concentration of a substance from one location to another.
Molecules diffuse down their concentration gradient.
Demonstrations

7. Diffusion is the movement of a substance from a region of higher concentration to a region of low concentration.
Osmosis is the movement of water from a region of high water concentration, through a semi permeable membrane, to a region of low water concentration.
Sugar molecule
Semi-permeable
membrane
Water molecule

8. A solution may be described as Isotonic, Hypertonic, or Hypotonic relative to another solution.
These terms are comparisons.
In other words: a solution may be described as Hypertonic only in comparison with another solution.

9. Equal concentration of solutes inside and outside of the cell.
Water will move into and out of the cell at equal rates.
Lower concentration of solutes outside of the cell.
Water will move into the cell.
Higher concentration of solutes outside of the cell.
Water will move out of the cell.

10. Some molecules can only diffuse through transport proteins.
Facilitated diffusion: diffusion through transport proteins – still doesn’t need energy

11. Chapter 3.5 Active Transport, Endocytosis and Exocytosis

12. Chapter 3.5 Active Transport, Endocytosis, Exocytosis
Objectives
Describe Active Transport
Distinguish between Endocytosis and Exocytosis.
You will accomplish this by taking notes, completing a foldable and drawing examples.

13. 3.5 KEY CONCEPT: Cells use energy to transport materials that cannot diffuse across a membrane.

14. ACTIVE TRANSPORT
REQUIRES ENERGY (ATP)
LOW >>>> HIGH CONCENTRATION
AGAINST THE GRADIENT
- PUMPS
- ENDOCYTOSIS
- EXOCYTOSIS

16. EXAMPLE: sodium / potassium pump

18. A cell can also use energy to import and export a large substance or large amounts of material in vesicles.
- Endocytosis
- Exocytosis.

22. Intracellular Receptor - EXAMPLE
The signal = ligand
Cell membrane
Nuclear envelope

23. Membrane Receptor - EXAMPLE