1. Transport of Molecules Across the Membrane

2. Cell Membrane Transport
Transport Flow Chart
Cell Membrane Transport
Passive Transport
Active Transport
Cotransport
Diffusion
Osmosis
Pumps
Facilitated
Diffusion

3. Passive Transport
REMEMBER…the membrane is semi-permeable and only lets certain molecules through the membrane without help
Passive transport is the movement of materials across the membrane without the use of energy. There are three types:
Diffusion
Facilitated Diffusion
Osmosis

4. Diffusion
Diffusion is the process by which small, uncharged particles move across the membrane.
They must move down the concentration gradient – meaning from an areas of high concentration to an area of low concentration
When the concentration on each side is equal movement does not stop. There is just no net change in the concentration on each side

5. Practice

6. Facilitated Diffusion
Is the same thing as diffusion except it allows large or charged particles to move across the membrane from an area of high concentration to an area of low concentration

7. The Proteins in the Membrane are similar to Enzymes

8. Which direction will the water move?
Osmosis
Osmosis is the movement of WATER across the membrane from an area of high concentration to an area of low concentration.
.4 M
.9 M
Which direction will the water move?

9. But…water hates fatty acids
Since water is polar it cannot flow through the membrane that easy
Protein channels called aquaporins allow water to move more quickly through the membrane
I can HELP!

10. New Terms for Osmosis
Hypotonic solution: A solution with a impermeable solute concentration lower than that of another solution or cell. Therefore the water will move into the cell. The cell will either swell or burst
.3 M
.5 M

11. New Terms for Osmosis
Hypertonic solution: A solution with a impermeable solute concentration composed higher than that of the another solution/or cell. Therefore, the water will move out the cell. The cell will shrink
.8 M
.5 M

12. New Terms for Osmosis
Isotonic solution: A solution with a impermeable solute concentration equal to that of another solution or cell. Therefore there will be no net movement of water.
.5 M
.5 M

13. A
.4 M Glucose
.6 M Sucrose B
.5 M Glucose
.5 M Sucrose
In the situation above the membrane is permeable to glucose but not sucrose
2. What will happen if the system is allowed to reach equilibrium
Glucose concentration will decrease in A, and the water level will increase
Glucose concentration will decrease in A, and the water level will decrease
Glucose concentration will increase in A, and the water level will decrease
Glucose concentration will increase in A, and the water level will increase

14. Practice A .4 M Glucose .6 M Sucrose B .5 M Glucose .5 M Sucrose
In the situation above the membrane is permeable to glucose but not sucrose
Which of the following is true
A is isotonic to B
A is hypotonic to B
A is hypertonic to C