1. Section Objectives
Predict the movement of water and other molecules across selectively permeable membranes. (SPI )
Compare and contrast active and passive transport. (SPI )
Relate diffusion and “dynamic” equilibrium.
Relate osmosis to solute concentration.
Describe how large molecules move across a membrane.

2. Section 7.4
Cellular Transport

3. Three Modes of Passive Transport
Passive Transport Movement of particles across the cell membrane without using energy
Diffusion
Facilitated Diffusion
Osmosis

4. Diffusion
The net movement of particles from an area of higher concentration to an area of lower concentration.
Initial Conditions
Diffusion
Low
High
High
Low

5. Dynamic Equilibrium
Reached when diffusion of material into the cell equals diffusion of material out of the cell
Molecules continue to move, but the overall concentration remains the same.

6. Molecules are always on the move!

9. Osmosis
This is a special term used to describe the passive transport of water across a selectively permeable membrane.

10. Water Balance in Animal Cells
This is a special term used to describe the passive transport of water across a selectively permeable membrane.

12. Isotonic Solution
Water and dissolved substances diffuse into and out of the cell at the same rate.
Blood Cell
Plant Cell

13. Hypotonic Solution Solute concentration is higher inside the cell.
Water diffuses into the cell.
Blood Cell
Plant Cell

14. Hypertonic Solution Solute concentration is higher outside the cell.
Water diffuses out of the cell.
Plant Cell
Blood Cell

15. Active Transport Using Carrier Proteins
Movement of particles across the cell membrane using energy
Active Transport Using Carrier Proteins

17. Transport of Large Molecules
Exocytosis
Endocytosis.

18. Endocytosis
Process by which the cell surrounds and takes particles into the cell
Exocytosis
Secretion of material out of the plasma membrane

19. Section 7.4 - Review Relate diffusion & equilibrium.
Describe passive transport.
How does osmosis relate to solute concentration?
Compare & contrast active and passive transport.
How do large molecules move across a membrane?