1. Cellular Transport– Maintaining homeostasis
SB1. Students will analyze the nature of the relationships between structures and functions in living cells.
Explain the role of cell organelles for both prokaryotic and eukaryotic cells, including the cell membrane, in maintaining homeostasis and cell reproduction.
d. Explain the impact of water on life processes (i.e., osmosis, diffusion).

2. A concentration gradient occurs when there is a strong concentration difference between two areas or spaces.

3. Transport– movement through the cell membrane
Passive Transport
Does not require energy
Movement is down the concentration gradient (high  low)
Diffusion
Osmosis
Facilitated diffusion
Active Transport
Does require energy
Movement is up the concentration gradient (low  high)
Membrane pumps
Endocytosis
Exocytosis

4. Diffusion
The movement of molecules or particles from an area of high concentration to an area of low concentration
Works for water and nonpolar solutes

5. Osmosis The diffusion of water

6. Words to compare solutions:
Hypertonic– the area of higher solute concentration
Hypotonic– the area of lower solute concentration
Isotonic– when the concentrations are the same

7. Solution: hypotonic solution: isotonic solution: hypertonic
Cell: hypertonic cell: isotonic cell: hypotonic
Water moves in water moves in & out water moves out
Cell swells & bursts cell stays the same cell shrivels up & dehydrates

8. Turgor Pressure
Pressure against the cell wall keeps structure for the plant.
Cell is hypertonic to environment.
Plants like hypotonic environments.
Plasmolysis
Cell contents shrink away from the cell wall.
Cell is hypotonic to environment.
Plants wilt in hypertonic environments.

9. Facilitated Diffusion
Moves materials across the cell membrane down the concentration gradient with the assistance of a transport protein
Works for polar molecules (typically large molecules or ions)

11. Membrane Pumps
Move substances up the concentration gradient with the assistance of a transport protein AND the use of energy (ATP)
Usually associated with the cell’s accumulation of necessary substances

12. Membrane Pumps

13. Endocytosis
The cell membrane engulfs particles of food or other materials and brings them into the cell.

14. Exocytosis The cell membrane lets things exit the cell.