1. Transport Moving Stuff Across the Membrane

2. Transport General Info
There are two broad categories for the classification of transport
Passive Transport:
Does not require energy and uses diffusion and concentration gradients to determine when to move across
Active Transport:
requires energy for movement
Usually against a concentration gradient
Only found in living things

3. Passive Transport high low
Diffusion: the movement of molecules from an area of ____________ concentration to an area of ____________ concentration until dynamic equilibrium is reached Dynamic Equilibrium: the flow of particles is equal in all directions
high
low

4. Diffusion Really????????? CO2 H2O H2O O2
Membrane is selectively permeable which means that O2, CO2 and H2O can easily move across the membrane; while large molecules or ions like glucose and sodium (Na+) cannot.
CO2 and O2 move in and out of the cell based on the concentration gradient established by the ECF and the cytoplasm of the cell. O2
CO2
H2O
H2O

5. Water and Diffusion Osmosis: The diffusion of water
What? Water diffuses?
Water diffuses from the ECF to the cytoplasm and vis versa due to solvent concentration
When you dissolve salt and sugar the water molecules have less room to move around.
Water molecules will try to reduce that restricted motion by filling the space with more water to reduce the solvent to solute ratio (dilution)
In order for cells to function they must maintain a balance between the concentration of the cytoplasm and ECF

6. The Tonics: ISOTONIC (ECF)
Total concentration of solutes in the cytoplasm is equal to the concentration of solutes in the ECF
WATER moves in and out of the cells in EQUAL volumes thus equilibrium is reached (balanced)

7. The Tonics: HYPERTONIC (ECF)
The ECF has a higher concentration of solutes
Water is drawn OUT of the cytoplasm causing the cell to SHRINK
The cell will shrink until a new equilibrium is reached or the cell dies, (shrivels up)
In plant cells this is called plasmolysis
Could happen to plants and animals in times of DROUGHT

8. The Tonics: HYPOTONIC (ECF)
The ECF has a lower concentration of solutes
Water is drawn INTO the cytoplasm causing the cell to SWELL
The cell will swell with water until a new equilibrium is reached or the cell BURSTS (Lysis)
Occurs when cells are submerged in water or we drink more than 60L of water

9. The Tonics

10. Passive Transport….there is more!!!!!!
Most molecule cannot move across the membrane easily
Even H2O has a tough time
Thus proteins are needed to get molecules across
When proteins help molecules get across the membrane but the molecules still move DOWN the concentration gradient it is called FACILITATED DIFFUSION
Two types of proteins carry out facilitated diffusion: Carrier proteins and Channel proteins

11. Facilitated Diffusion
Property
Carrier Proteins
Channel Proteins
Shape
Unique 3-D Shape
Tunnel-like shape
Type of Molecule they transport across the membrane
Non-charged molecules of specific size and shape (ex. Glucose)
Small charged molecules that can fit into the “tunnel” ex. Ions
Number of molecules they transport across membrane
Single type of molecule or single group of closely related molecules
Many molecules of correct charge at the same time
Mode of Operation
Transmembrane and change shape when desired molecules bind
Transmembrane proteins that do not move but instead act like a selective pore
Gated channel proteins open and close to allow certain molecules through
Aquaporin
Channel protein that allows water to diffuse through more readily (urinary tract)

12. Carrier Protein
Channel Protein