1. Cells
Active & Passive transport

3. Phospholipid bilayer Made of Phospholipid molecules Heads (polar)
Tails (nonpolar)
Form impermeable barrier

4. Fluid Mosaic Model
Fluid  Bilayer has “fluid” consistency  molecules “float”
“Mosaic”  Proteins, Carbs & Lipids “float” in bilayer

5. Selective Permeability
Some substances can get through, some cannot
Glucose & other ions, molecules have to use transport proteins

6. Passive & Active Passive Active
Movement of molecules in and out of the cell
Does not require energy
Moves stuff with the Concentration Gradient
Two types
OSMOSIS
DIFUSION
Active
Movement of molecules in and out of the cell
Requires energy (ATP)
Requires some type of protein
Moves stuff against the Concentration Gradient

7. Passive Transport Diffusion
Molecules are driven by molecular motion/collisions

8. Passive Transport Diffusion
Molecules move from  to  concentration  equilibrium
Solutes may be:
Molecules (solid, liquid or gas)
Ions (cations [+], anions [-])
Solvent (biological) is water
How O2 & CO2 pass in & out of cell membrane

9. Passive Transport Osmosis
Diffusion of solvent molecules (usually water)
Tonicity:
Ability of surrounding solns to cause cells to gain/lose water
Osmoregulation-control of water balance

10. Hypertonic
Higher concentration on solutes (which means lower concentration of SOLVENT…aka water)
Cells SHRINK in a Hypertonic solution

11. Hypotonic
SOLUTE concentration is lower (and SOLVENT concentration is higher)
Cells SWELL in a hypotonic solution

12. Isotonic
SOLUTE concentration is the same inside and outside the cell (so is the SOLVENT)  Equilibrium
Cells don’t change size in Isotonic solutions

13. Passive Transport Results

14. Facilitated Diffusion
Imbedded protein helps move molecules across membrane
Doesn’t require energy (still high to low)
Some hydrophilic
Other hydrophilic molecules can pass through

15. Active Transport Moves substance against concentration gradient
“Carrier-mediated”—always uses a carrier protein
Always requires addition of energy P
Protein changes shape
Phosphate detaches
ATP
ADP
Solute
Transport protein

16. Active Transport Na+/K+ pump
With the help of ATP, the carrier protein changes shape
3 Na+ leave cell
2 K+ enter cell
1/3 of all the energy used by cells is used to drive the Na+/K+ pump!

17. Enzymatic Proteins Enzymes that are bound into the membrane
Carry out reactions
Ex. ATP Synthase  generate ATP

18. “Bulk” Transport Endocytosis
Phagocytosis: Ingestion of large molecules
Pinocytosis: Ingestion of small molecules or liquid

19. “Bulk” Transport Exocytosis
Vesicles fuse with plasma membrane and “dump” contents!
Eliminate wastes
Secretion of molecules
Contractile vacuoles
Fluid outside cell
Cytoplasm
Protein
Vesicle