1. Passive Transport
Learning Targets 4-6

2. Passive Transport Cellular Transport
Fact: Particles of matter are always in motion no matter what state this random motion helps explain how materials enter and exit the cell
There are 2 ways that materials enter and exit the
cell wall
Passive Transport- (Without using cell energy)
Diffusion, Facilitated Diffusion, or Osmosis
2. Active Transport- (Requiring cell energy)

3. This is gonna be hard work!!
Active Transport
1. Protein Pumps
2. Endocytosis
3. Exocytosis
Passive Transport
1. Diffusion
2. Facilitated Diffusion
3. Osmosis
high
low
This is gonna be hard work!!
high
low
Wheee!!!

4. Diffusion (Passive Transport)
What is It?
Moving molecules have Kinetic Energy
Particles collide and rebound
Particles do not lose energy
Diffusion- The overall movement of particles from high concentration to low concentration (by random particle movement)
How does it work?
Most substances in and around the cell are in H20
Solutes (Molecules, ions, etc) are usually distributed evenly in the water by the random movement of molecules
When the distribution of all of the solutes in the solution is even, the particles can collide but there is no change in concentration

5. Passive Transport Results?
If the concentrations inside and outside the cell are not in Dynamic Equilibrium then the molecules will move according to the concentration gradient
Flow is always from High to low
High Concentration Low Concentration = With the gradient
Low Concentration High Concentration = Against the gradient
!! (No longer a concentration gradient, no dynamic equilibrium) !!
The selective permeability of the cell membrane is not great for allowing ions or polar molecules to pass by diffusion because they are not attracted to non-polar fatty acids. Only a few molecules can pass by diffusion. They include… H2O, O2, N2, CO2

6. Osmosis (Passive Transport)
What is it?
Osmosis- Diffusion of H2O through a selectively permeable membrane from high to low concentration

7. NOT AT DYNAMIC EQUILIBRIUM
Osmosis
Before
High conc of H2O on left of Membrane/
low conc of solute
Low conc of H2O on right of Membrane/
High conc of solute
After
H2O molecules move from high conc , across
The membrane, to low conc until DYNAMIC
EQUILIBRIUM is reached.
(conc solute/water on left = conc solute/ water on right)
NOT AT DYNAMIC EQUILIBRIUM

8. Osmosis Isotonic: Concentrated molecules on the inside =
Concentrated molecules on the outside
Random motion allows water in and out, but at the same rate
Therefore No
concentration gradient

9. Osmosis 2. Hypotonic: Concentration Solutes on the Outside <
Concentration Solutes inside
High water on outside, low water inside
Water goes into cell, and cell swells
Increase in cell pressure called TURGOR PRESSURE

10. Osmosis 3. Hypertonic- Concentration Solute Outside >
Concentration Solute Inside
High Water inside, low water outside
Water goes out of cell and decreases cell pressure
Cell Shrivels
Plasmolysis- Loss of cell pressure

11. Bellringer
The two main parts of the cell membrane’s phospholipid bilayer are…?
________________ and b. ______________

12. Bellringer
From the Sandwich Baggie Demo, we learned iodine molecules were able to pass through the membrane because they were…?
Small enough
Attracted to the starch
Very large
Faster to diffuse than starch
molecules

13. Bellringer
The Cell Membrane Test is coming soon. Mrs. Weber set up a study group to facilitate our studying. What does the word facilitate mean?

14. Bellringer
Water and other molecules don’t always share e-’s equally. This give the molecules a partially positive and partially negative charge. We say these molecules are POLAR.
Does the cell membrane easily
allow polar molecules?
Y or N
Which part of the cell membrane is hydrophobic
and dislikes polar molecules? _________________

15. Facilitated Diffusion (Passive Transport)
!! Okay…so molecules pass through the cell membrane based on…
Size
-Small molecules pass easily,
-Large molecules do not or cannot
Polarity (if the molecule has charged ends it will not be able to pass the hydrophobic lipids)
Polar

16. Facilitated Diffusion
Ions
Facilitated Diffusion
Sugars
Q: How do LARGE or POLAR molecules enter the cell?
A: Through PROTEINS!
Common for Sugars, Amino Acids, or charged molecules like ions or polar molecules.
Amino Acids

17. Facilitated Diffusion (Passive Transport)
Proteins HELP or FACILITATE the passage of larger or polar molecules
Kinds of Proteins
Channel Proteins
-have a tube down the middle of the protein thru which molecules can diffuse
Carrier Proteins
-change their shape to fit specific molecules

18. Facilitated Diffusion Animation