1. Movement Across the Plasma Membrane
The cell membrane is semi-permeable
A few molecules move freely
Water, Carbon dioxide, Ammonia, Oxygen
Carrier proteins transport other molecules
Proteins embedded in lipid bilayer
Fluid mosaic model – describes fluid nature of a lipid bilayer with proteins

4. Three Transport types: (don’t write this down)
1. Passive Transport
2. Active Transport
3. Membrane-assisted Transport
Endocytosis
(phagocytosis & pinocytosis)
Exocytosis

5. 1. Passive Transport No energy required Move due to gradient
differences in concentration, pressure, charge
Move to equalize gradient
High moves toward low

7. Types of Passive Transport
a) Diffusion
b) Osmosis
c) Facilitated diffusion

8. a) Diffusion
Molecules move to equalize concentration

9. Rate of diffusion - how fast diffusion occurs
Factors that affect the rate of diffusion are
Molecule size
- bigger are slower
Molecule polarity
- more polar are slower
Ion charge
- more charged are slower

10. d) Temperature
- directly proportional
e) Pressure

11. b) Osmosis
Diffusion of water
Into cell
Out of cell

12. Solution Differences & Cells
solvent + solute = solution

13. Solutions can be: i. Hypotonic solution
More solutes in cell than outside
Outside solvent will flow into cell

14. Draw it!

15. ii. Hypertonic solution
More solutes outside than inside cell
Fluid will flow out of cell

16. Draw it!

17. iii. Isotonic solution
Solutes equal inside & out of cell

18. Draw it!

20. c) Facilitated Diffusion
Membranes are differentially permeable
Still passive transport: why???

21. i. Specific channel proteins help molecule or ions enter or leave the cell
Hollow tubes
Ex. aquaporins

22. ii. Specific carrier proteins transport molecules across the cell membrane
Slower than channels (lower rate of diffusion)
Ex. Cytochromes: involved in ATP production

23. Process of Facilitated Transport
1. Protein binds with molecule
2. Shape of protein changes
3. Molecule moves across membrane

24. 2. Active Transport Primary Active Transport
against concentration gradient!
Requires energy (ATP)
Ex. sodium-potassium pump

26. If the primary active transport involves ions it creates an electrochemical gradient
Combination of a concentration gradient and charge
Stores potential energy

27. b) Secondary Active Transport
Uses the electrochemical gradient as a source of energy
Used in uptake of amino acids and sugars
Ex. Hydrogen-sucrose pump

31. 3. Membrane-assisted transport

32. trans-face
cis-face

33. a) Endocytosis Movement of large material Movement is into cell
Particles
Organisms
Large molecules
Movement is into cell
Types of endocytosis
bulk-phase (nonspecific)
receptor-mediated (specific)

34. Process of Endocytosis
1. Plasma membrane surrounds material
2. Edges of membrane meet
3. Membranes fuse to form vesicle

35. Forms of Endocytosis i) Phagocytosis – cell eating
ii) Pinocytosis – cell drinking

36. b) Exocytosis
Reverse of endocytosis
Cell discharges material

37. Steps 1. Vesicle moves to cell surface 2. Membrane of vesicle fuses
3. Materials expelled

39. End Chapter 2