October 30, 2007

1. Diffussion, thermodiffusion. Biological role of diffusion Osmosis, chemiosmosis The microscopic transport of material October 30, 2007 Lustyik

2. Examples for the biological role of diffusion

3. 2 = 6Dt D R R = 1 cm: 8300 s (2 h 18 m) R = 3 mm (E. coli): 7.5 x 10-5 s Motion of small molecules: Diffusion of water in water: D = 2 x 10-9 m2/s

4. Dx = 10 nm DC = 500 mM Dn/Dt = -D *A/Dx * Dc Movement of K+ ions through the plasma membrane Diffusion of K+ ions in water: D = 10-16 m2/s 100 nm x 100 nm 3 x 104 K+ ion /sec

5. Convective transport Diffusion Convective transport O2 CO2 Diffusion Légzés Blood flow Cells and tissues

6. 2 D R = 6Dt Oxygen and CO2 exchange in the lung CO2 Alveolus of the lung ~1 mm Alveolar epithelium O2 Kapillary vessel Kapillary endothelium toxigen ~500 ms Doxigen = 10-9 m2/s tCO2 ~80 ms DCO2 = 6 x 10-9 m2/s

7. P A + B k k Ha k k << D D k k k -D -D 2 1 1 k = 2 Diffusion limited rections Reaction constants P A + B AB Racting molecules Product Reaction complex

8. FRAP (Fluorescence Recovery After Photobleaching) Cell D Nucleus

9. Bleaching FRAP recovery curve Fluorescence intensity Recovery Time

10. FRAP Myoblast, expressing a compound that contains GFP (Green Fluorescence Protein)

11. dn dr dt df = - Drot f Rotational diffusion, Florescence anisotropy

12. kT Drot= fR fR = 8phr3 Measurement with fluorescence anisotropy kT Drot= = 2Drott Df 2 3 8phr

13. Cell membrane + + + + + + + + + + + + + + + + + + DU Diffusion potencial

14. RT u+ - u- d(lnc) dU = zF u+ + u- Diffusion potential: „ion mobility” Integration of this equation provides the Goldman-Hodgkin-Katz equation

15. Biological role of diffusion Osmosis, chemiosmosis The microscopic transport of material October 30, 2007 Lustyik

18. Osmosis Semipermeable wall or membrane Solvent Solute

19. Alcohol Alcohol Nollet Abbe, 1748 Water Este Reggel Dutrochet, 1830 Sucrose solution

20. Models of osmosis: Vant’Hoff law Thermodynamic theory

21. p = RTc h p = h r g vant’Hoff’s law Pure water p = p Solution Jacobus Hendricus van’t Hoff (1852-1911)

22. + Vpmp1 p1 p2 mo1 mo2 Thermodynamic theory Chemical potential of the solvent: mo1 = moo + RT ln xo1 Vpm: parcial molar volume

23. p1 p2 mo1 mo2 Equilibrium: mo1 = mo2 mo1 = moo + RT ln xo1 + Vpmp1 mo2 = moo + RT ln xo2 + Vpmp2

24. mo1 = moo + RT ln xo1 + Vpmp1 mo2 = moo + RT ln xo2 + Vpmp2 xo2 RT p2 – p1 = ln xo1 Vpm p = mo1 = mo2

25. RT xo2 p = ln xo1 Vpm One compartment is pure solvent (xo1=1) The solution is incompressible (Vpm=konstans) Solvent concentration is low = c (concentration of the solute) Vant’Hoff’s law: p = RTc

26. Molality: The number of moles of solute in 1 kg of solvent p = RTc Molarity: The number of moles of solute in 1 kg of solution

27. Ozmolarity = =molarity x number of dissociated ions 0,3 M glicerin: 0,3 Osmol 0,6 Osmol 0,3 M NaCl (Na+, Cl-):

28. Isotonic solutions: If their ospmotic pressure is equal Isotonic solutions with blood and cytoplasm: 0,15 M-os (0,87%) NaCl solution 5,5%-os glucose solution 3,8%-os Na-citrate solution

29. Human and animal cells Plant cells Isotonic solution Hypotonic solution Hypertonic solution

30. Thermoosmosis Equal concentrations (at start) Cold Warm Dilution concentration Solvent transport fom the warmer to the cooler side

31. Biological, medical importance and application: • Lysing red blood cells for clinical laboratory • Development of oedemas • Oedema treatment with hypertonic solution • Mg-szulfát: causing diarrhea • Hemodialisis of patients suffering from kidney insufficiency • Dialisis of laboratory specimens

32. Isotonic solution = isoosmotic solution p = s RTc „reflection” coefficient 0 < s < 1 • Colloid osmotic pressure • Membrane is permeable to the solvent

33. Dp Szemipermeable membrane s = 1 Hidrostatic pressure difference „Leaky” membrane s < 1 Time „leaky”: permeable to the solvent

34. DV Shrinking (water uptake) Volume regulation Ion transport, release of isotonic solution Change of cell volume Time Volume regulation of living animal cells

35. Jk = Lk1 X1 + Lk2 X2 + … + Lkn Xn k = 1, 2, 3, …n Jv = LppDp + LpdDp Jd = LpdDp + LddDp Flow maintained by thermodynamic forces: Onsager equations: Jv: „volume” flow Jd: diffussion (osmotic) flow

36. JQ Dp Jv Thermoosmosis DT Dc Jm Je DU Diffusion Volume flow Heat flow Pressure difference Concentration difference Temperature difference Elektric potencial difference Electric current Mass transport

37. Chemiosmosis

38. CyC Q + + Cytochromsystem ATP ATP Synthase I II O2 ADP NADH NAD+ OH- III OH- ADP ATP Chemiosmosis

39. CyC Q + + Citokróm rendszer ATP ATP Synthase I II O2 ADP NADH NAD+ OH- III OH- ADP ATP Ca2+ No “Mitochondrial Permeability Transition Pore” +Cy A

40. Membrare potencial in mitochondria Intact Damaged

41. Limited and Facilitated Diffusion Additional cellular transport mechanisms

42. Passive transport (simple diffusion) Facilitated diffusion Cell membrane Lipid bilayer Membrane proteins

43. www.whfreeman.com

45. Special, diffusion associated cellular mechanisms Chemotaxis: The ability of an organism or cell to move towards or against concentration gradient of a specific chemical compound Inflamatory response: Migration towards the inflamatory center Bacterial migration for finding regions that it deems favorable Sporulation of amebas

46. Running: flagella turn counterclockwise „Tumbling”: flagella turn clockwise Random walking on organelle scale.