1. Without your book or notes
Tell me . . .
The 3 principles of cell theory
The difference between prokaryotes & Eukaryotes
What a cell’s plasma membrane is composed of.
Of the two part of the molecule that makes up the plasma membrane, which end is hydrophobic and which end is hydrophilic

3. Cellular Transport
7.4

4. How do substances move across a membrane?

5. Simple Diffusion (Passive Transport)
The tendency of molecules to move from a high concentration to a low concentration.
Diffusion continues until all molecules are equally spread out or they reach their dynamic equilibrium.

6. Molecules move down their concentration gradient across the cell membrane.
Molecules will continue to move until they reach their dynamic equilibrium

8. Facilitated Diffusion
Type of Passive transport
No Energy is required
Protein Channels help move ions and other small molecules across the membrane.

9. Facilitated Diffusion- Passive Transport
Some molecules can’t diffuse across the membrane on their own and need a facilitator.

10. Some molecules and ions move across the cell’s membrane with the help of protein channels. These channels “facilitate” or help the diffusion of the molecules/ ions.

11. So what about the movement of H2O?
Osmosis- the movement of water across a selectively permeable membrane.
Remember our cell membrane is selectively permeable

12. Water molecules diffusing across the cell’s membrane.

13. Terms to Know
Remember: A solution is a solute evenly distributed in a solvent (kool-aid)
Concentration: measure of the amount of solute dissolved in a solvent.
If there is more solvent than solute the solution would have a low concentration.

14. Let’s Look At It
Molecules cannot pass through the membrane only water.
Which direction does the water move?
Right
Why?
Higher concentration of solute on right side.

15. Would the concentration of sugar solution increase or decrease as the water moves?
Water will continue to move back and forth (diffuse) until dynamic equilibrium is reached.

16. Salt Sucks Remember When dissolved in water, salt is a solute.
When concentrated inside or outside the cell, it will draw (suck) the water in its direction

17. Understanding Osmosis can help us determine whether water will move into or out of cells depending on the type of solution it is placed in.

18. Hypotonic Solution
Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water)
Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

19. Hypertonic Solution
Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water)
Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

20. Isotonic Solution
Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell.
Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

21. Hypertonic
Isotonic
Hypotonic

22. Dialysis
Blood passes through a semipermeable membrane which acts like a filter.
Clean Blood returns to the body

23. How does drinking salt water dehydrate you?
Explain how salt water dehydrates using the information we have discussed.
Use the new vocabulary

24. Active Transport cell uses energy
actively moves molecules to where they are needed
Movement from an area of low concentration to an area of high concentration
(Low  High)
Three Types:

25. Protein Pump
Protein changes shape to move molecules against their concentration gradient. This requires energy!

26. Na+/ K+ ATPase pump
Maintains the levels of Na+ and K+ ions inside and outside the cell.
3 Na+ leave cell & 2 K+ enter cell through a protein that catalyzes the break down of ATP (ATPase)
Inside of cell is now more – and outside of cell more +
Na+ diffuses back into cell

27. Other molecules like glucose, amino acids, and other nutrients “piggyback” the Na+ back into the cell through a coupled channel.
These other molecules can enter the cell without spending additional cellular energy

28. Endocytosis Endocytosis: taking bulky material into a cell Uses energy
Cell membrane in-folds around food particle
“cell eating”
forms food vacuole & digests food
This is how white blood cells eat bacteria!

29. Exocytosis
. Exocytosis: Forces material out of cell membrane. The surrounding material fuses with cell membrane
Cell changes shape – requires energy
EX: Hormones or wastes released from cell