Transport in Plants I

1. Transport in Plants I If you're not part of the solution, you're part of the precipitate. -   Steven Wright

2. ? Rote Concept/Process oriented Question Integrated question, i.e spanning chapters Good Excellent Not so Good Business • Quiz: mean = last term, ~6/9 (not good enough), • didn’t study enough, • studied, did well, with tinkering will master, • studied, but didn’t do too well, • probably memorized terms, without grounding the words in reality. • Midterm I: one week from Friday, • Essay questions due Tuesday afternoon, 3 pm. • email to young@biol.wwu.edu, • Subject Line must say 206 Question, • Include your name, if your email address is esoteric, • 2 extra credit point (maximum) if you provide at least one GOOD question, and email it, on time, and with correct subject line.

3. Today • Introduction to Transport, • Mechanisms of Transport, • passive, • active, • Questions, Extra Credit?

4. Transport …molecular and ionic movement from one location to another, • H2O, • Sugars, • Minerals, • Gases, • Other Macromolecules: proteins, RNA, hormones, etc.

5. Plant Transport(What’s Transported) • H2O, • uptake by roots, transport via xylem, loss to the atmosphere and metabolic processes, • Minerals (in solution), • Uptake by roots, loss to senescence, herbivory, etc. Xylem

6. Plant Transport(What’s Transported) • Gases, • CO2, O2, H2O. • N2, ethylene, etc. Stomates

7. Plant Transport(What’s Transported) • Sugars, • other organics, • hormones, • amino acids, • etc. Phloem by-directional

8. Plant Transport(What’s Transported) • Roots, • uptake O2, • discharge CO2. Gas Exchange/Respiration

9. Everything Symplastic and Apoplastic Then Plant Transport Across Membrane(s) First

10. Pressure, Concentration gradients, (entropy-driven diffusion). What Drives Transport? Gravity, Electrical fields, (for charged substances),

11. Mechanisms of Transportin organisms • Diffusion, by molecular motion, • good only at short distances, • Diffusion, by molecular motion, • good only at short distances, • Pump, Channel and Carrier mediated transport, • small molecules across membranes, • Osmosis (water across membranes), • Bulk Flow, • efficient large-scale, mass movement.

12. concentration gradient Js = Ds flux density “flow rate” change in distance Dcs diffusion constant Dx Fick’s First Law“Uber Diffusion” (1855) Adolf Fick

13. Adolf Fick: Contributions • Ophtalmotonometer – Intraocular pressure • Aneroid manometer – Vascular grad (BP) • Pneumograph – Peripheral thorax variation link • Plethysmography – I/O of blood, air in lungs, etc. • Dynamometer – Muscle output • Laws of diffusion 1855 • Contact lens

14. L2 tc = 1/2 = Ds Fick’s Law and Organisms • Ds for sucrose is ~10-9 m2 s-1, • 50 mm: tc = 1/2 = 2.5 seconds, • 1 m: tc = 1/2 = 32 years. (tc = 1/2) for a molecule to move (p = 0.5) a set distance (L)... … is equal to the distance (L) squared divided by the diffusion coefficient (Ds).

15. 50mm Choleochaete orbicularis Trees ? Bryophytes Fick’s Law and Organisms Chlamydomonas reinhardii

16. Mechanisms of Transportin organisms • Diffusion, by molecular motion, • good only at short distances, • Pump, Channel and Carrier mediated transport, • small molecules across membranes, • Osmosis (water across membranes), • Bulk Flow, • efficient large-scale, mass movement.

17. Membranes • Plasma Membrane (1x), • Plastids (2x), • Mitochondria (2x), • Vacuole (1x), • Golgi, ER (1x), • Peroxisomes, etc. ( 1x).

18. Arabidopsis Genome Coordinated Transport

19. H+ (protons) ATP synthase Transporters - carriers, - channels. ATP hydrolase (ATPase) Adapted from Biochemistry and Molecular Biology of Plants, pp. 115

20. vacuolar organelles ATP Pumpsall organisms

21. P-Type ATPases Phylogentic Family Tree

22. animals 10 transporters plants, animals, fungus, yeast animals, plants, fungus, yeast bacteria, animals, plants, etc. P-Type ATPasesplasma membrane …ATP driven cation pumps (typical), NA+ K+ H+ K+ H+ Ca 2+ Cd2+ Hg2+ Cu2+

23. Plasma Membrane Proton Pump (ATPase) X 2 H+ ATP 2 H+ X D 300 mV Plasma Membrane H+-ATPases H+ H+ H+ H+ H+ H+ H+ H+ symport ADP + Pi H+ antiport H+ Transport channels ions

24. Mechanisms of Transport • Diffusion, by molecular motion, • good only at short distances, • Channel and Carrier mediated transport • small molecules across membranes, • Osmosis (water across membranes), • Bulk Flow, • efficient large-scale, mass movement.

25. Osmosis …the diffusion of water across a selectively permeable membrane, • water (free) moves from a region of higher H2O concentration, to a region of lower H2O concentration, until in equilibrium, …the concentration of water is lowered by the addition of solutes.

26. Mechanisms of Transport • Diffusion, by molecular motion, • good only at short distances, • Channel and Carrier mediated transport • small molecules across membranes, • Osmosis (water across membranes), • Bulk Flow, • efficient large-scale, mass movement.

27. Jean Louis Marie Poiseuille (Poiseuille’s Law, ~1838) pressure gradient pr4 DYp Volume flow rate = in a cylinder 8h Dx distance viscosity (h) Bulk Flow …the concentrated movement of groups of molecules, • in response to gravity, i.e. rain, rivers, etc., • in biological systems, most often in response to pressure. viscous: tendency to resist flow

28. pr4 DYp 8h Dx distance viscosity (h) Increase Flow? Increase radius. Lower Viscosity. Increase Pressure. Shorten Distance. pressure gradient Volume flow rate =

29. Friday • Water and Water Potential, • Cell Water Relations, • Water Transport in Plants. Catch up in the readings, review materials from 204 and 205 if necessary.