1. MOVEMENT OF MATERIALS THROUGH THE CELL MEMBRANE

2. Background Info…
Every living cell contains a liquid interior and is surrounded by a liquid
One of the most important functions of the cell membrane is to regulate the movement of molecules from one side of the membrane to the other

3. Background Info…
Carbohydrates act like chemical identification cards for other cells
The core of nearly all cell membranes is a LIPID BILAYER which is a tough flexible structure
Protein channels pumps help move materials across

4. PASSIVE TRANSPORT
No energy needed because movement occurs down the concentration gradient (from high concentration to low concent.)
There are 3 types of passive transport:
1. Diffusion
2. Osmosis
3. Facilitated Diffusion

5. 1. Diffusion
Movement of molecules from an area of greater concentration to an area of lesser concentration
*continues until equilibrium is reached; molecules will continue to move in both directions at the same rate

6. 2. Osmosis Diffusion of water across a selectively permeable membrane
Some substances can pass through the membrane & others cannot
Ex: carrot in salt water; water can pass through the carrot cell membrane but salt cannot

7. OUTSIDE THE CELL
INSIDE THE CELL

8. Osmotic Pressure Pressure created by osmosis
Cells are filled with sugars, salts, proteins, and other molecules
If a cell is placed in fresh water, which way will the water move?
INTO THE CELL!! Which will cause the cell to swell and burst
Why doesn’t this happen in your body?
Blood has same amount of solutes as cells
Plant cells are surrounded by tough cell walls

9. ISOTONIC solution: Concentration of water & sugar same on both sides of membrane. Molecules will continue to move in both directions at the same rate (Osmosis continues until equilibrium is reached)
HYPERTONIC solution: Higher concentration of solutes outside the cell than inside the cell itself, water leaves the cell through osmosis. (Lower solute concentration inside cell)
HYPOTONIC solution: Lower concentration of solute outside the cell than inside the cell, water will enter it through osmosis. (Higher solute concentration inside cell)

11. 3. Facilitated Diffusion
involves the use of protein channels located in the cell membrane
protein channels help material across
*glucose transported across this way

12. ACTIVE TRANSPORT
requires energy because material is moved across the membrane against the concentration gradient (from low concentration to high concent.)
Compared to a pump!

13. WHY DO WE NEED THIS PROCESS?:

14. We need active transport in order to…
1. Transport (or pump) macromolecules across the cell membrane
Ex: Na+/ K+ pump; Ca+2 ions (responsible for nerve impulses)
Cell uses energy to force ions across the membrane, like you would use energy to force a boulder up a hill

15. Na/K Pump Video Examples Dying from drinking to much water Wii
Examples
Dying from drinking to much water
Wii
Chico 2005

16. We need active transport for…
2. Endocytosis- taking materials into a cell (forms a vacuole within the cytoplasm)
ex: phagocytosis: large particles are engulfed

18. We need active transport for…
Exocytosis- bulk passage
out of the cell