1. TRANSPORT!

2. Picky membrane The lipid bilayer is semipermeable
Nonpolar molecules pass easily through the membrane
Polar molecules (ions, water, etc) don’t pass through easily
Transport proteins/ channel proteins
Aquaporins
Ion Channels

3. Move ‘em OUT!
Substances are constantly moving through the cell membrane
Passive Transport~ does not require any energy
Active Transport~ needs ATP from the cell

4. Diffusion
Diffusion~ tendency of any molecule to spread out into available space
Concentration gradient~ difference in concentration across a space
In passive transport, molecules always move down the concentration gradient

5. Diffusion will continue until the concentration of solute is evenly distributed throughout a space (equilibrium).

6. Osmosis
Osmosis~ the diffusion of water across a selectively permeable membrane
Hypertonic~ higher concentration of solutes
Hypotonic~ lower concentration of solutes
Isotonic~ equal concentrations of solutes

7. Osmoregulation = control of water balance
Hypotonic- water moves into the cell
Hypertonic- water moves out of the cell
Isotonic- water movement is stable
Cells with Walls:
Turgid in hypotonic
Flaccid in isotonic
Plasmolyzed in hypertonic
Plasmolysis~ plasma membrane pulls away from cell wall

8. Facilitated Diffusion
Uses transport proteins
Channel proteins
Carrier proteins
Passive Transport (no NRG needed)
Passage of ions and large molecules

9. Active Transport Against concentration gradient Requires ATP Ion Pumps
Set up a charge, or membrane potential, across membrane
Ions flow with their electrochemical gradient

10. Sodium-Potassium Pump

11. Electrogenic pump Cotransport Proton pump
Stores up voltage that can be used for cell processes
Cotransport
Molecules can “follow” ions back into the cell along their electrochemical gradient

12. Bulk Transport
Exocytosis~ release of macromolecules by vesicles fusing with the plasma membrane
Secretions
How waste is released

13. Endocytosis~ import of macromolecules by forming new vesicles with the plasma membrane
Phagocytosis (solids)
Pinocytosis (liquids)
receptor-mediated endocytosis (ligands)