Transport in Plants I

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Transport in Plants I

• If you're not part of the solution, you're part
  of the precipitate.
• -   Steven Wright

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Business

• Quiz mean last term, 6/9 (not good enough),
• didnt study enough,
• studied, did well, with tinkering will master,
• studied, but didnt 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_at_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.

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Today

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

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Transport

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

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Plant Transport(Whats Transported)
Xylem

• 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.

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Plant Transport(Whats Transported)
Stomates

• Gases,
• CO2, O2, H2O.
• N2, ethylene, etc.

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Plant Transport(Whats Transported)
Phloem bydirecional

• Sugars,
• other organics,
• hormones,
• amino acids,
• etc.

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Plant Transport(Whats Transported)
Gas Exchange/Respiration

• Roots,
• uptake O2,
• discharge CO2.

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Plant Transport
Across Membrane(s)
First
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What Drives Transport?
Gravity,
Electrical fields, (for charged substances),
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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.

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Ficks First LawUber Diffusion (1855) Adolf
Fick
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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

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Ficks Law and Organisms
(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).

• Ds for sucrose is 10-9 m2 s-1,
• 50 mm tc 1/2 2.5 seconds,
• 1 m tc 1/2 32 years.

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Ficks Law and Organisms
Chlamydomonas reinhardii
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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.

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Membranes
Plasma Membrane (1x), Plastids
(2x), Mitochondria (2x), Vacuole (1x), Golgi,
ER (1x), Peroxisomes, etc. ( 1x).
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Coordinated Transport
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H (protons)
ATP synthase
Transporters - carriers, - channels.
ATP hydrolase (ATPase)
Adapted from Biochemistry and Molecular Biology
of Plants, pp. 115
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ATP Pumpsall organisms
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P-Type ATPases Phylogentic Family Tree
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P-Type ATPasesplasma membrane

• ATP driven cation pumps (typical),

NA K H K H Ca 2 Cd2 Hg2 Cu2
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Plasma Membrane H-ATPases
H
H
H
H
H
H
H
H symport
ADP Pi
H antiport
H
Transport channels
ions
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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.

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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.

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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.

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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
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Increase Flow?

• Increase radius.
• Lower Viscosity.
• Increase Pressure.
• Shorten Distance.

pressure gradient
Volume flow rate
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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.