1. Membranes

2. Cell Membranes Are selectively permeable
Allow some small molecules to pass freely whereas large molecules can’t
Some small molecules move more easily than others (this is different from a semi-permeable membrane)

3. Ways to enter & exit Diffusion and osmosis 2 types of Endocytosis:
Transport by carriers
Endocytosis and exocytosis
2 types of Endocytosis:
Large molecules = phagocytosis (cell “eating”)
Small molecules = pinocytosis (cell “drinking”)

5. Rate of Diffusion: Affected by concentration gradient
Also affected by…
size/shape of molecule
temperature
state of medium through which diffusion occurs

6. Osmosis Net movement (diffusion) of H2O Osmosis continues until…
Osmotic Pressure = Hydrostatic Pressure
Pressure due to flow of H2O Pressure exerted by liquid
(with solute)
*When equal, EQUILIBRIUM is reached

8. Types of Solutions (Tonicity)
Concentration given as a % of solution
Ex. 20% salt solution is 80% water
Tonicity = strength of solution
1. Isotonic:
Cells in isotonic solutions won’t gain or lose H20
[Outside Cell] = [Inside Cell]
Ex. 0.9% NaCl solution is ISOTONIC to red blood cells

9. 2. Hypertonic
Hyper = “greater”
Cell loses H20 to its surroundings
Cell becomes shrivelled (crenated)
Ex. Cell contains 0.1% glucose; solution outside contains 0.5% glucose

10. 3. Hypotonic
Hypo = “lower”
Cell at risk of bursting (lysis)
Ex. Cell contains 0.1% glucose; solution outside contains 0.01% glucose

11. U-Tube Example A B
Volume on Side B: Increase as water moves Glucose [ ] on Side A: Increase (lower water [ ]) Protein [ ] on Side B: Decrease as water moves to side B
5% glucose
95% water
20% glucose
10% protein
70% water