2. Cell Membrane Functions
Protects and supports the cell
Regulates the transport of materials in & out of the cell

3. Cell Membrane Structure
OUTSIDE
Lipid Bilayer: a double layer sheet of phospholipids that makes up the cell membrane.
“Water-loving”
“Water-fearing”
INSIDE

4. The Fluid Mosaic Model The cell membrane is made of many different
parts that freely move.

5. Selectively Permeable
Yeah!
I made it!
Selectively Permeable
Some substances can pass through the cell membrane
But others can’t.
Permea- means “porous” or “pass through”
Help!
I can’t fit!

6. Passive Transport Movement of substances into/out of cell
without using energy.
HIGH  LOW concentration
3 types:
Simple Diffusion
Faciliated Diffusion
Osmosis
Weeee!!!
HIGH
LOW

7. Simple Diffusion concentration (concentration gradient)
Molecules move from HIGH to LOW
concentration (concentration gradient)
Until balanced or equal- “at equilibrium”

8. At Equilibrium Molecules still move around But…No NET flow
Diffusion
HIGH  LOW
(concentration gradient)

9. Facilitated Diffusion
Some molecules can’t diffuse through the membrane and require special protein channels to move through.
Ex. Ions, glucose
LOW
HIGH

10. Osmosis
 Diffusion of water through special channels called aquaporins.
 Moves from HIGH to LOW concentration.

11. Solvent + Solute = Solution
Solvent: does the dissolving, like water
Solute: substance that gets dissolved
in the solvent

12. How Osmosis Works Isotonic Hypertonic Hypotonic “same or equal”
“above or higher”
Hypotonic
“below or lower”
EQUAL amounts of
solute in/out of cell.
HIGHER solute
outside.
LOWER solute

13. How Osmosis Works Isotonic Hypertonic Hypotonic “same or equal”
“above or higher”
Hypotonic
“below or lower”
Water in/out. Cell stays the same.
Water out.
Cell shrinks.
Water in. Cell swells.

14. BrainPOP: Passive Transport
s/passivetransport/preview.weml

15. Iso, Hypo or Hyper? ISOTONIC 10% NaCL 90% H2O CELL 10% NaCL 90% H2O
ENVIRONMENT
CELL
10% NaCL
90% H2O

16. Water goes?
IN/OUT
10% NaCL
90% H2O
ENVIRONMENT
CELL
10% NaCL
90% H2O

17. Iso, Hypo or Hyper? HYPOTONIC 10% NaCL 90% H2O CELL 20% NaCL 80% H2O
ENVIRONMENT
CELL
20% NaCL
80% H2O

18. Water goes? IN
10% NaCL
90% H2O
ENVIRONMENT
CELL
20% NaCL
80% H2O

19. Iso, Hypo or Hyper? HYPERTONIC 10% NaCL 90% H2O CELL 5% NaCL 95% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O

20. Water goes?
OUT
10% NaCL
90% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O