1. Membrane Transport

2. 3 Types of transport

3. Passive Transport Simple diffusion –Small non-polar molecules No ions –Examples: Fatty acids Steroids CO 2 O 2 H 2 O (?)—osmosis –Only move DOWN concentration gradient

5. Osmosis

6. Osmosis, con't.

7. Mediated Transport Passive mediated transport –Facilitated diffusion Carrier proteins Channel proteins –DOWN a conc. gradient Active transport –Primary active transport—uses ATP –Secondary active transport—uses a different energy source –Pumps things UP a conc. gradient

8. How to tell mediated transport vs. simple diffusion Saturation kinetics Competition kinetics Specificity

9. Some more terms

10. GluT1 (RBCs)—a carrier protein

11. Channel proteins Ion channels –Ions –Selective –Generally gated Porins –Larger –Less specific Aquaporins –water

12. Porins

13. The Pore-Forming Toxins Lethal molecules produced by many organisms Insert themselves into the host cell plasma membrane Kill by –collapsing ion gradients –facilitating entry by toxic agents –introducing a harmful catalytic activity

14. Colicins Produced by E. coli Inhibit growth of other bacteria (even other strains of E. coli) Single colicin molecule can kill a host!

16. Other Pore-Forming Toxins Hemolysin from –Staphylococcus aureus –a symmetrical pore Aerolysin –Aeromona hydrophila Anthrax toxin protective antigen –Bacillus anthracis

17. Hemolysin

18. Ionophore Antibiotics

19. Valinomycin Cyclic peptide Valinomycin- potassium complex diffuses freely and rapid across membranes

20. Gramicidin—pore forming

22. Active Transport

23. Direct and Indirect AT

25. The Na/K ATPase

27. Consequences of Na/K ATPase Two ion gradients –Used as energy source –Electrical signaling Charge difference across membrane –Membrane potential difference –Negative on inside -60 to –90 mV in animal cells ~ -150 mV in bacteria -200 to –300 mV in plants –Not just due to these ions Phosphatidylserine on inside of PM Other ions

28. Indirect (secondary) AT Na/glucose symporter –Intestinal absorptive cells

31. Energetics of Transport

32. Thermodynamics of Transport, charged