1. Transportation of substances across a cell membrane

2. [A] Passive Transport Spontaneous – does not require energy
eg. rocks rolling down a hill
Three types:
Diffusion
Osmosis
Facilitated Diffusion

3. 1. Diffusion
The movement of molecules from a region of high concentration to a region of low concentration
Molecules move down the concentration gradient

4. Diffusion and the Living Cell
Cell membrane acts as a barrier which allows certain things into the cell and certain things out
Selectively Permeable Membrane
eg. O2 diffuses into a cell and CO2 diffuses out
Like your hearing!

5. Equilibrium
Pg. 89 Fig 1

6. Selectively Permeable
Impermeable
Does not allow molecules to pass
Permeable
Allows molecules to pass freely
Selectively Permeable
Permits some molecules and controls others

7. 2. Facilitated Diffusion
Diffusion across a membrane at a rate faster than normally expected
Some form of assistance (protein molecule)

8. Transport proteins: 2 Types
Channel protein
Aqueous channel allows polar molecules and ions to pass
Some open all the time, some have gates that respond to different signals (eg. hormones, electric charges, pressure, or light)
Cystic fibrosis is a result of defective chloride ion channel protein

9. Carrier protein Bind specifically to molecules they assist
Similar to an enzyme binding to its substrate
Has lower rates of diffusion compared to channel protein because they can only bind to a few molecules at once
Cystinurea (painful stones that block the urinary tract) is a result of the inability of a carrier protein to remove cystine and amino acids from urine
Pg. 91 Fig 4

11. 3. Osmosis
Diffusion of water from a high concentration to a low concentration across a semi-permeable membrane
Concentration: measure of amount of solute in a solution
Solution: combination of solvent with one or more solutes
Solvent: part of a solution that the solute dissolves (eg. water)
Solute: part of a solution that becomes dissolved (eg. salt)

13. Isotonic solution
A solution that has the same solute concentration as another solution

16. Hypertonic solution
A solution that has a higher solute concentration than another solution

17. Cell in a hypertonic solution

18. Hypotonic solution
A solution that has a lower solute concentration than another solution

19. Cell in a hypotonic solution

20. In animal cells:
under hypotonic conditions the cell may HEMOLYSIS (burst)
under hypertonic conditions the cell may undergo CRENATION (shrink)
In plant cells:
under hypotonic conditions the cell becomes TURGID (bulges)
under hypertonic condition the cell may PLASMOLYSIS (pull away
from cell wall)
Turgor Pressure – osmosis in plants where water accumulates in vacuoles
causing pressure on the cell wall

21. p. 92 Fig 6

22. [b] Active Transport Cells must use energy (ATP)
Moves substances against a concentration gradient (up hill)

26. [C] Membrane Assisted Transport
Similar to active transport – requires energy
Two forms:
Endocytosis
Exocytosis

27. 1. endocytosis
Cell engulfs material by folding the cell membrane around it and forms a vesicle inside the cell
Three methods
Phagocytosis
Pinocytosis
Receptor mediated endocytosis

28. phagocytosis ‘Cell eating’
Taking in of discrete particles or fragmented matter
Pg. 96 Fig 11

29. pinocytosis
‘Cell drinking’
Taking in of liquids
Pg. 96 Fig 11

30. Receptor-mediated endocytosis
Uses receptor proteins on cell membrane to bind with specific molecules.
Outside layer is created with protein  coated pit
Pg. 96 Fig 12

32. 2. exocytosis Macromolecules and other large particles leaving cell
Products to be released, or waste material, are contained in a vesicle that fuses with the cell membrane and empties contents in extra cellular environment
In plant cells  helps construct the cell wall
In animal cells  secretes hormones, neurotransmitters, digestive enzymes, etc

33. Pg. 95 Fig 10

35. Section 2.4
Answer p. 97 #3, 4, 9
Answer SG 2.4 #1-3, 8, 9