1. Chapter 3.2 The Cell in Its Environment

2. How Do Substances Cross the Cell Membrane?
Nutrients
Water
Waste materials

3. Diffusion
Movement of material until equilibrium is reached

4. Osmosis
Diffusion of water until equilibrium is met

5. Effects of Osmosis on Red Blood Cells

6. Effects of Osmosis on Plant Cells

7. Plasmolysis (Shrinking of the Cell Membrane)
What is the purple stuff?
Can you see the cell membrane shrinking away from the cell wall?
Why would this happen?

8. Alternative Viewing of Plasmolysis
Red Onion Skin placed in 10% salt solution
Watch as osmosis causes the cell to change shape

9. Your Turn (if there is time)
Working as a table group, prepare 2 slides.
Make a wet slide of red onion skin using a 2% salt solution.
Make a wet slide of red onion skin using tap water.
Share and observe cells under low or high power.
Observe plant cells
in dynamic equilibrium
undergoing plasmolysis

10. Active Transport Rowing upstream
Read and take 2 column notes on p84-85
HW: Complete notes, if not done in class.

11. Transport Across the Cell Membrane How Much Energy Does it Take?
Passive Transport
Active Transport
Diffusion
Osmosis

12. Transport Across the Cell Membrane
Passive Transport
Active Transport
Diffusion
Osmosis
Notice the Transport Protein

13. Transport by Engulfing Endocytosis

14. Expelling Large Substances Exocytosis

15. Why are Cells So Small? Talk with your partner:
Can you think of 2 reasons why large cells don’t survive?
(the images might give you clues)

16. What will happen if you place a Gummi Bear in...
tap water
distilled water

17. Diffusion
Movement of material until equilibrium is reached

18. Osmosis
Diffusion of water until equilibrium is met