1. Transport through the Cell Membrane
A. Passive Transport
passive transport is the movement of molecules through the cell membrane without cellular energy
there are 3 types: diffusion; osmosis; and facilitated diffusion

2. 1. Diffusion molecules are in constant motion
diffusion is the process by which particles move naturally from an area of HIGH concentration to an area of LOW concentration until a dynamic equilibrium is reached (no net movement)
[high] [low]
this is called moving “with the concentration gradient”
small molecules diffuse through the phospholipids of the cell membrane (e.g. O2, CO2, H2O, alcohol, small lipids)

3. Factors that affect diffusion
concentration. of particles ( conc.,  rate of diffusion)
temperature. of particles ( temp.,  rate of diffusion)
pressure ( pressure,  rate of diffusion)
agitation ( movement,  rate of diffusion)

4. 2. Osmosis Three types of membranes: impermeable permeable
osmosis is the diffusion of water through a semi- permeable membrane
Three types of membranes:
impermeable
permeable
semi-permeable
Which membrane is most like a cell membrane?

5. Three terms for solutions:
Solute: the dissolved substance, e.g. salt
Solvent: able to dissolve things, e.g. water
Solution: mixture of solvent and solute
Three types of solutions:
Hypertonic solution: the solution surrounding the cell has a higher [solute] than the cell’s cytoplasm, water moves out of the cell
Hypotonic solution: the solution surrounding the cell has a lower [solute] than the cell’s cytoplasm, water moves into the cell
Isotonic solution: the [solute] is the same in the cell’s cytoplasm and in the solution surrounding the cell

6. What will happen to red blood cells placed in a salt water solution?

7. It depends on the type of solution they are placed in.
Hypertonic
Isotonic
Hypotonic
More water diffused out of the cells
Water diffused equally in and out of the cells
More water diffused into the cells

8. Turgor pressure
the rigid cell wall of plant cells prevents them from bursting when they are filled with water
water in vacuoles causes an outward push called turgor pressure
plant cells swollen with water are said to be turgid
Plasmolysis
when plant cells are placed in a salt solution, the cells shrink, this is called plasmolysis

9. 3. Facilitated Diffusion
some molecules are too large or are hydrophilic, and cannot pass through the phospholipids
transport proteins assist these molecules through the cell membrane (e.g. glucose)
transport protein
transport occurs with the concentration gradient (no energy is required)

10. B. Active Transport
active transport is the movement of molecules through the cell membrane against the concentration gradient using transport proteins
[low] [high]
this process requires the use of cellular energy (ATP)
transport proteins are highly selective (e.g. Na+/K+ pump)

11. Active vs. Passive Transport
Facilitated
Diffusion
Active
Transport
Diffusion

12. C. Transport by Vesicles
a) Endocytosis:
transport of material into a cell by means of vesicles
cell engulfs material by folding a portion of its membrane around it
energy is required
3 types of endocytosis:
1. phagocytosis, cell eating;
movement of large molecules and whole cells into the cell’s interior

13. 2. pinocytosis: cell drinking;
transport of liquids into vesicles inside cell
3. receptor-mediated endocytosis:
molecules bind to receptors on cell’s surface and are folded into vesicles within the cell

14. b) Exocytosis:
transport of macromolecules (e.g. hormones) out of a cell by means of vesicles made by the Golgi complex;
energy is required

15. Work on review in the booklet