Transport in Plants I If you're not part of the solution, you're part of the precipitate. - Steven...
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Transcript of Transport in Plants I If you're not part of the solution, you're part of the precipitate. - Steven...
Transport in Plants I
If you're not part of the solution, you're part of the precipitate.
- Steven Wright
Salmonberry bird…
Rubus spectabilisSalmonberry
Rhizomes
Clones
Leaves Alternet
• Local (NW) flora,• Ethnobotany,• Fun!
Buy locally, or at Amazon ($16.47).
Today
• Introduction to Transport,
• Mechanisms of Transport,
– passive,– active,
• Questions, Extra Credit?
Transport
…molecular and ionic movement from one location to another,
– H2O,
– Sugars,
– Minerals,
– Gases,
– Other Macromolecules: proteins, RNA, hormones, etc.
Plant Transport(What’s Transported)
• H2O,
– uptake by roots, transport via xylem, loss to the atmosphere and metabolic process,
• Minerals (in solution),
– Uptake by roots, loss to senescence, herbivory, etc.
Xylem
Plant Transport(What’s Transported)
• Gases,
– CO2, O2, H2O.
– N2, ethylene, etc.
Stomates
Plant Transport(What’s Transported)
• Sugars,
• other organics,
– hormones, – amino acids,– etc.
Phloembydirecional
Plant Transport(What’s Transported)
• Roots, »
– uptake O2,
– discharge CO2.
Gas Exchange/Respiration
Plant Transport
Symplastic and ApoplasticEverything
Across Membrane(s)
First Then
What Drives Transport?
Gravity,
Pressure,
Electrical fields, (for charged substances),
Concentration gradients, (entropy-driven diffusion).
• 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.
Mechanisms of Transportin organisms
• Diffusion, by molecular motion,
– good only at short distances,
Fick’s First Law“Uber Diffusion” (1855) Adolf Fick
Js = Ds
cs
x
flux densityflow rate
concentration gradient
change in distance
diffusion constant
Adolf Fick: Contributions
• Ophtalmotonometer – Intraocular pressure
• Aneroid manometer – Vascular grad (BP)
• Pneumograph – Peripheral thorax variation
• Plethysmography – I/O of blood, air in lungs, etc.
• Dynamometer – Muscle output
• Laws of diffusion 1855
• Contact lens
Fick’s Law and Organisms
tc = 1/2 = L2
Ds
(tc = 1/2) for a molecule to move a set distance (L)...
… is equal to the distance (L) squared divided by the diffusion coefficient (Ds).
• Ds for sucrose is ~10-9 m2 s-1,
– 50 m: tc = 1/2 = 2.5 seconds,
– 1 m: tc = 1/2 = 32 years.
Fick’s Law and Organisms
Choleochaete orbicularis
50m
Trees ?Bryophytes
Chlamydomonas reinhardii
• 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.
Mechanisms of Transportin organisms
Membranes
Plasma Membrane (1x),
Plastids (2x),
Mitochondria (2x),
Vacuole (1x),
Golgi, ER (1x),
Peroxisomes, etc. ( 1x).
Coordinated Transport
Arabidopsis Genome
Adapted from Biochemistry and Molecular Biology of Plants, pp. 115
H+ (protons) ATP synthase
ATP hydrolase (ATPase)
Transporters
- carriers, - channels.
ATP Pumpsall organisms
vacuolar organelles
P-Type ATPasesPhylogentic Family
Tree
P-Type ATPasesplasma membrane
…ATP driven cation pumps (typical),
NA+ K+
H+ K+
H+ Ca 2+ Cd2+ Hg2+ Cu2+
animals
plants, fungus, yeast
animals, plants, fungus, yeast
bacteria, animals, plants, etc.
10 transporters
Plasma Membrane H+-ATPases
ATP ADP + Pi
X
2 H+
H+
Transport channels
H+ symport
H+ antiport
Plasma Membrane
2 H+
X
Proton Pump(ATPase)
H+ H+
H+
H+H+
H+
H+
300 mV
ions
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.
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.
Review Ch.8
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.
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.
r4
8
p
xVolume flow rate =
in a cylinder
viscosity ( distance
pressure gradient
viscous: tendency to resist flow
Jean Louis Marie Poiseuille (Poiseuille’s Law, ~1838)
Increase Flow?Increase radius.
Lower Viscosity.Increase Pressure.Shorten Distance.
r4
8
p
xVolume flow rate =
viscosity ( distance
pressure gradient
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.