Learning Targets 4-6

Passive Transport

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 thecell wall1. Passive Transport- (Without using cell energy)

Diffusion, Facilitated Diffusion, or Osmosis2. Active Transport- (Requiring cell energy)

Active Transport 1. Protein Pumps

2. Endocytosis3. Exocytosis

Passive Transport 1. Diffusion

2. Facilitated Diffusion 3. Osmosis

high

low

Wheee!!!

high

low

This is gonna

be hard work!!

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

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 diffusion, @ 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

Osmosis (Passive Transport)

What is it? Osmosis- Diffusion of H2O through a selectively permeable membrane from high to low concentration

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 DYNAMICEQUILIBRIUM is reached.(conc solute/water on left = conc solute/ water on right)

Osmosis

NOT AT DYNAMIC EQUILIBRIUM

Osmosis1. 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

Osmosis2. 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

Osmosis3. 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

Bellringer1. The two main parts of the cell membrane’s

phospholipid bilayer are…?

a. ________________ and b. ______________

Bellringer2. From the Sandwich Baggie Demo, we

learned iodine molecules were able to pass through the membrane because they were…?

a. Small enoughb. Attracted to the starchc. Very larged. Faster to diffuse than starch molecules

Bellringer3. The Cell Membrane Test is coming

soon. Mrs. Weber set up a study group to facilitate our studying. What does the word facilitate mean?

Bellringer4. 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.

a. Does the cell membrane easily allow polar molecules? Y or N

b. Which part of the cell membrane is hydrophobic and dislikes polar molecules? _________________

Facilitated Diffusion (Passive Transport)

!! Okay…so molecules pass through the cell membrane based on…

1. Size -Small molecules pass easily, -Large molecules do not or cannot

2. Polarity (if the molecule has charged ends it will not be able to pass the hydrophobic lipids)

Polar

Facilitated Diffusion

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.

Sugars Ions

Amino Acids

Facilitated Diffusion (Passive Transport)

Proteins HELP or FACILITATE the passage of larger or polar molecules

Kinds of Proteins1. Channel Proteins

-have a tube down the middle of the protein thru which molecules can diffuse

2. Carrier Proteins-change their shape to fit specific molecules

Facilitated Diffusion Animation