Chapter 3: Cells

1. Chapter 3: Cells Section 4: Diffusion and Osmosis Chapter 3: Cells Section 4: Diffusion and Osmosis

2. Chapter 3: Cells Section 4: Diffusion and Osmosis Agenda • Do Now! • Body Spray Graphing Activity • Passive Transport Presentation

3. Chapter 3: Cells Section 4: Diffusion and Osmosis Do Now! Think about the graphs you have made in the past. In your Biology notebook, write down as many characteristics of a good line graph as you can think of.

4. Chapter 3: Cells Section 4: Diffusion and Osmosis • Molecules move randomly What kind of energy is represented by this motion? • In all matter, molecules are always moving randomly and bumping in to each other.

5. Diffusion Chapter 3: Cells Section 4: Diffusion and Osmosis • Diffusion is the movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration • “diffuse” means “spread out” or “to spread out”

6. Chapter 3: Cells Section 4: Diffusion and Osmosis

7. Diffusion Chapter 3: Cells Section 4: Diffusion and Osmosis • Is a type of passive transport • Passive transport uses no energy to move molecules • “Passive” means “not participating readily or activ-ely”

8. Chapter 3: Cells Section 4: Diffusion and Osmosis • “Diffusion”

9. Chapter 3: Cells Section 4: Diffusion and Osmosis Low concentration Equal concentration High concentration

10. Chapter 3: Cells Section 4: Diffusion and Osmosis • “Diffusion of Food Coloring in a Water Solution”

11. Concentration Gradient Chapter 3: Cells Section 4: Diffusion and Osmosis • A concentration gradient is the difference in the concentration of a substance from one region to another. • Molecules move “down” a concentration gradient

12. Chapter 3: Cells Section 4: Diffusion and Osmosis

13. Chapter 3: Cells Section 4: Diffusion and Osmosis learn

14. Osmosis Chapter 3: Cells Section 4: Diffusion and Osmosis • Osmosis is diffusion across a semi-permeable membrane. • Because it is a type of diffusion, osmosis is also passive transport • Osmosis is critical to the health of cells

15. Chapter 3: Cells Section 4: Diffusion and Osmosis • "Osmosis"

16. Chapter 3: Cells Section 4: Diffusion and Osmosis Check for Understanding: How many fingers?

17. Solutions with a Membrane Chapter 3: Cells Section 4: Diffusion and Osmosis • The concentration of a solute may be different on one side of a membrane than the other. • The words isotonic, hypertonic, and hypotonic help us to compare these two environments. • “iso” = “same” • “hyper” = “more” • “hypo” = “less”

18. Solutions with a Membrane Chapter 3: Cells Section 4: Diffusion and Osmosis • AnIsotonicsolution has the same amount of solute on both sides of the membrane or cell. • A Hypertonic solution has more solute than inside the membrane or cell. • A Hypotonic solution has less solute than inside the membrane or cell.

19. Chapter 3: Cells Section 4: Diffusion and Osmosis “same” “more” “less”

20. Facilitated Diffusion Chapter 3: Cells Section 4: Diffusion and Osmosis • Facilitated diffusion is a special case of osmosis. • Molecules that are too big and/or too polar need help to cross the cell membrane! • Molecules that cannot normally cross the cell membrane may be helped across by transport channel proteins

21. Chapter 3: Cells Section 4: Diffusion and Osmosis

22. Chapter 3: Cells Section 4: Diffusion and Osmosis