1. Cellular Transport
10/16/06

2. Cellular Transport
Cells need to maintain the proper balance of solutes (like sugar and minerals) and solvent (water) inside the cell no matter what environment it is in.
They do this by using the membrane to bring in or keep out the things they need (cellular transport)

3. Types of Cellular Transport
Passive Transport – cellular transport that does NOT require energy (ATP) because it goes with the concentration ([ ]) gradient.
Diffusion
Facilitated Diffusion
Osmosis
Active Transport – cellular transport that requires energy (ATP) because it goes against the [ ] gradient.
Protein-mediated active transport
Endocytosis
Exocytosis
Pinocystosis

4. Diffusion
Diffusion is the natural movement of solute particles from an area of high concentration to an area of low concentration (down a concentration gradient).
Equilibrium – the state reached when the molecules are evenly spread out.

5. Diffusion

6. Facilitated Diffusion
Facilitated Diffusion – diffusion that occurs when a membrane protein helps a solute that normally can’t pass through the membrane get across down its concentration gradient.
CD Activity 5I

7. Osmosis
Osmosis is the diffusion of water across a semi-permeable membrane.

8. Osmosis
Hypotonic Solution - contains less solute particles than another solution. Water osmoses OUT of a hypotonic solution.
Hypertonic Solution - contains more solute particles than another solution. Water osmoses INTO a hypertonic solution.
Isotonic Solutions - contain equal concentrations of solute particles. Water will flow both ways across the membrane to stay equal.

9. Water Balance in Cells Cells placed in a: CD Activity 5J
hypotonic solution will fill up with water and lyse (pop).
Hypertonic solution will shrivel up.
Isotonic solution will remain the same size.
CD Activity 5J

10. Active Transport
Protein-Mediated Active Transport – a membrane proteins pumps a solute across the membrane against its concentration gradient.
Exocytosis – a vesicle (membrane bubble) containing waste products inside the cell merges with the cell membrane and casts its contents out.
Endocytosis
Phagocytosis – cell eating; a portion of the membrane wraps around a macromolecule (large molecule), and pinches off to form a vesicle inside the cell.
Pinocytosis – cell drinking; small vesicles form at the cell membrane around nonspecific samples of the cell’s environment.