1. CELL
TRANSPORT
Passive Active
- Molecules enter or - Many molecules
leave one at at time enter or leave
together (i.e. bulk
transport)

2. PASSIVE
Facilitated
Diffusion Osmosis
Diffusion
- no cell energy needed
- molecules move with the concentration
gradient (high to low) due to random
molecule motion

3. ACTIVE
Carrier Bulk
Exocytosis
Protein Transport
- cell energy is needed
- molecules move against the
concentration gradient (low to high)

4. Cell Membrane
Which of the following is NOT a characteristic
of the cell membrane:
a) made up of phospholipids
b) selectively permeable
c) controls the flow of materials
d) provides rigid support for the cell

5. Cell Membrane
a) made up of phospholipids
- two layers of lipids
b) selectively permeable
- lets some things in, not others
c) controls the flow of materials
- in and out of the cell (its main job!)
d) provides rigid support for the cell
- FALSE: this is for the cell wall

6. Cell Membrane & Transport
Two important parts for transport:
1. Bilayer of
phospholipids
2. Channel
proteins

7. 1) Diffusion
 even net flow of molecules from an area of
high concentration low concentration
Examples
- perfume
- tea bag

8. 1) Diffusion
 moves WITH the concentration gradient
concentration gradient: a difference in
concentration between two areas
 continues until concentrations are equal

9. 1) Diffusion
The rate (speed) of diffusion is affected by:
 Temperature
 faster at higher temperatures
 Concentration of solute (what is dissolved)
molecules in a solution
 faster if solute concentration is high

10. 2) Osmosis
 diffusion of water molecules across a
selectively permeable membrane
 a specific type of diffusion
 moves WITH the concentration
gradient

11. Diffusion & Osmosis
These processes can occur in two ways:
1) Directly through the cell membrane
 small, uncharged molecules
(O2, CO2, H2O)
2) Through protein channels
 charged ions and water
(Na+, Ca2+, K+, Cl-)

12. Protein Channels

13. 3) Facilitated Diffusion
 used for molecules that are too large to
pass unassisted through the cell
membrane or channel protein
 these molecules have to use carrier
proteins
 examples) glucose, amino acids

14. a) molecule bounces into a binding site
b) carrier protein accepts molecule
c) carrier changes shape & flips over, bringing
molecule into cell
d) carrier protein returns to its shape (no picture)