Bio 226: Cell and Molecular Biology

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Mineral Nutrition Studied by soil-free culture in
nutrient solutions
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• Mineral Nutrition
• Macronutrients CHOPKNSCaFeMg
• Ca signaling, middle lamella, cofactor
• Fe cofactor
• Mg cofactor
• mobile in plant, so shows first in old leaves

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• Mineral Nutrition
• Micronutrients BNaCl others include Cu, Zn, Mn
• B cell elongation. NA metabolism
• Na PEP regeneration, K substitute
• Cl water-splitting, osmotic balance
• Cu cofactor
• immobile in plant, so shows first in young leaves

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Mineral Nutrition Commercial fertilizers mainly
supply NPK
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• Plant food
• 2.6 ammoniacal nitrogen
• 4.4 nitrate nitrogen
• 9 phosphorus
• 5 potassium
• calcium (2)
• magnesium (0.5)
• sulfur (0.05)
• boron (0.02)
• chlorine (0.1)
• cobalt (0.0015)
• copper (0.05)
• iron (0.1)
• manganese (0.05)
• molybdenum (0.0009)
• nickel (0.0001)
• sodium (0.10)
• zinc (0.05)

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• Mineral Nutrition
• Soil nutrients
• Amounts availability vary
• Many are immobile, eg P, Fe

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• Mineral Nutrition
• Soil nutrients
• Amounts availability vary
• Many are immobile, eg P, Fe
• Mobile nutrients come with soil H2O

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• Mineral Nutrition
• Soil nutrients
• Amounts availability vary
• Many are immobile, eg P, Fe
• Mobile nutrients come with soil H2O
• Immobiles must be mined
• Root hairs get close

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• Mineral Nutrition
• Immobile nutrients must be mined
• Root hairs get close
• Mycorrhizae get closer

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• Mineral Nutrition
• Immobile nutrients must be mined
• Root hairs get close
• Mycorrhizae get closer
• Solubility varies w pH

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• Mineral Nutrition
• Solubility varies w pH
• 5.5 is best compromise

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• Mineral Nutrition
• Solubility varies w pH
• 5.5 is best compromise
• Plants alter pH _at_ roots to
• aid uptake

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• Mineral Nutrition
• Nutrients in soil
• Plants alter pH _at_ roots to aid uptake
• Also use symbionts
• Mycorrhizal fungi help especially with P

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• Mineral Nutrition
• Also use symbionts
• Mycorrhizal fungi help especially with P
• P travels poorly fungal hyphae are longer
  thinner

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• Mineral Nutrition
• Also use symbionts
• Mycorrhizal fungi help especially with P
• P travels poorly fungal hyphae are longer
  thinner
• Fungi give plants nutrients

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• Mineral Nutrition
• Also use symbionts
• Mycorrhizal fungi help especially with P
• P travels poorly fungal hyphae are longer
  thinner
• Fungi give plants nutrients
• Plants feed them sugar

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• Mineral Nutrition
• Also use symbionts
• Mycorrhizal fungi help especially with P
• P travels poorly fungal hyphae are longer
  thinner
• Fungi give plants nutrients
• Plants feed them sugar
• Ectomycorrhizae surround root only trees, esp.
  conifers

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• Mineral Nutrition
• Ectomycorrhizae surround root only trees, esp.
  conifers
• release nutrients into apoplast to be taken up
  by roots

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• Mineral Nutrition
• Ectomycorrhizae surround root trees
• release nutrients into apoplast to be taken up by
  roots
• Endomycorrhizae invade root cells
  Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor
  soils

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• Mineral Nutrition
• Endomycorrhizae invade root cells
  Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor
  soils
• May deliver nutrients into symplast

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• Rhizosphere
• Endomycorrhizae invade root cells
  Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor
  soils
• May deliver nutrients into symplast
• Or may release them when arbuscule dies

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• Rhizosphere
• Endomycorrhizae invade root cells
  Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor
  soils
• Deliver nutrients into symplast or release them
  when arbuscule dies
• Also find bacteria, actinomycetes, protozoa
  associated with root surface rhizosphere

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• Rhizosphere
• Also find bacteria, actinomycetes, protozoa
  associated with root surface rhizosphere
• Plants feed them lots of C!

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• Rhizosphere
• Also find bacteria, actinomycetes, protozoa
  associated with root surface rhizosphere
• Plants feed them lots of C!
• They help make nutrients available

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• Rhizosphere
• Also find bacteria, actinomycetes, protozoa
  associated with root surface rhizosphere
• Plants feed them lots of C!
• They help make nutrients available
• N-fixing bacteria supply N to many plant spp

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• Rhizosphere
• N-fixing bacteria supply N to many plant spp
• Most live in root nodules are fed protected
  from O2 by plant

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• Nutrient uptake
• Most nutrients are dissolved in water

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• Nutrient uptake
• Most nutrients are dissolved in water
• Enter root through apoplast until hit endodermis

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• Nutrient uptake
• Most nutrients are dissolved in water
• Enter root through apoplast until hit endodermis
• Then must cross plasma membrane

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Crossing membranes A) Diffusion through bilayer
B) Difusion through protein pore C)
Facilitated diffusion D) Active transport E) Bulk
transport 1) Exocytosis 2) Endocytosis
Selective
Active
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• Nutrient uptake
• Then must cross plasma membrane
• Gases, small uncharged non-polar molecules
  diffuse

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• Nutrient uptake
• Then must cross plasma membrane
• Gases, small uncharged non-polar molecules
  diffuse
• down their ?
• Important for CO2, auxin NH3 transport

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• Nutrient uptake
• Then must cross plasma membrane
• Gases, small uncharged non-polar molecules
  diffuse
• down their ?
• Polar chems must go through proteins!

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Selective Transport 1) Channels integral membrane
proteins with pore that specific ions diffuse
through
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• Selective Transport
• 1) Channels
• integral membrane proteins with pore that
  specific ions diffuse through
• depends on size
• charge

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• Channels
• integral membrane proteins with pore
• that specific ions diffuse through
• depends on size charge
• O in selectivity filter bind
• ion (replace H2O)

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• Channels
• integral membrane proteins with pore
• that specific ions diffuse through
• depends on size charge
• O in selectivity filter bind
• ion (replace H2O)
• only right one fits

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• Channels
• O in selectivity filter bind
• ion (replace H2O)
• only right one fits
• driving force?
• electrochemical D

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Channels driving force electrochemical
D non-saturable
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Channels driving force electrochemical
D non-saturable regulate by opening closing
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Channels regulate by opening closing ligand-gate
d channels open/close when bind specific chemicals
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Channels ligand-gated channels open/close when
bind specific chemicals Stress-activated channels
open/close in response to mechanical stimulation
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Channels Stress-activated channels open/close in
response to mechanical stimulation voltage-gated
channels open/close in response to changes in
electrical potential
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• Channels
• Old model S4 slides up/down
• Paddle model S4 rotates

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• Channels
• Old model S4 slides up/down
• Paddle model S4 rotates
• 3 states
• Closed
• Open
• Inactivated

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Selective Transport 1) Channels 2) Facilitated
Diffusion (carriers) Carrier binds molecule
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Selective Transport Facilitated Diffusion
(carriers) Carrier binds molecule carries it
through membrane releases it inside
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Selective Transport Facilitated Diffusion
(carriers) Carrier binds molecule carries it
through membrane releases it inside driving
force ?
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Selective Transport Facilitated Diffusion
(carriers) Carrier binds molecule carries it
through membrane releases it inside driving
force ? Important for sugar transport
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Selective Transport Facilitated Diffusion
(carriers) Characteristics 1) saturable 2)
specific 3) passive transports down ?
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Selective Transport 1) Channels 2) Facilitated
Diffusion (carriers) Passive transport should
equalize Nothing in a plant cell is at
equilibrium!
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Selective Transport Passive transport should
equalize Nothing in a plant cell is at
equilibrium! Solution use energy to transport
specific ions against their ?
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• Active Transport
• Integral membrane proteins
• use energy to transport specific ions against
  their ?
• allow cells to concentrate some chemicals,
  exclude others

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Active Transport Characteristics 1) saturable
102-104 molecules/s
105-106 ions/s
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Active Transport Characteristics 1) saturable 2)
specific
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Active Transport Characteristics 1) saturable 2)
specific 3) active transport up ? (or ? Em)
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• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• Na/K pump
• Ca pump in ER PM
• H pump in PM
• pumps H out of cell

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• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• 2) V-type ATPases (V vacuole)
• H pump in vacuoles

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• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• 2) V-type ATPases (Vvacuole)
• 3) F-type ATPases (F factor) a.k.a. ATP
  synthases
• mitochondrial ATP synthase
• chloroplast ATP synthase

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• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• 2) V-type ATPases (V vacuole)
• 3) F-type ATPases (F factor)
• 4) ABC ATPases (ABC ATP Binding Cassette)
• multidrug resistance proteins

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• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• 2) V-type ATPases (V vacuole)
• 3) F-type ATPases (F factor)
• 4) ABC ATPases (ABC ATP Binding Cassette)
• multidrug resistance proteins
• pump hydrophobic drugs out of cells
• very broad specificity

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Secondary active transport Uses ? created by
active transport to pump something else across a
membrane against its ?
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Secondary active transport Uses ? created by
active transport to pump something else across a
membrane against its ? Symport both
substances pumped same way
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Secondary active transport Uses ? created by
active transport to pump something else across a
membrane against its ? Symport both
substances pumped same way Antiport substances
pumped opposite ways
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Secondary active transport Uses ? created by
active transport to pump something else across a
membrane against its ? Symport both
substances pumped same way Antiport substances
pumped opposite ways
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• Rhizosphere
• Ectomycorrhizae surround root
• Endomycorrhizae invade root cells
  Vesicular/Arbuscular
• Also find bacteria, actinomycetes, protozoa
  associated with root surface rhizosphere
• Chemicals that harm rhizosphere microbes harm
  plants!

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• Rhizosphere
• Ectomycorrhizae surround root
• Endomycorrhizae invade root cells
  Vesicular/Arbuscular
• Also find bacteria, actinomycetes, protozoa
  associated with root surface rhizosphere
• Chemicals that harm rhizosphere microbes harm
  plants!
• Root-microbe interactions help take up
  rhizosphere metals

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• Nutrient uptake
• Most nutrients are dissolved in water
• Enter root through apoplast until hit endodermis
• Then must cross plasma membrane

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Crossing membranes A) Diffusion through bilayer
B) Difusion through protein pore C)
Facilitated diffusion D) Active transport E) Bulk
transport 1) Exocytosis 2) Endocytosis
Selective
Active
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• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• 2) V-type ATPases (V vacuole)
• 3) F-type ATPases (F factor)
• 4) ABC ATPases (ABC ATP Binding Cassette)
• multidrug resistance proteins

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Secondary active transport Uses ? created by
active transport to pump something else across a
membrane against its ? Symport both
substances pumped same way Antiport substances
pumped opposite ways
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Nutrient uptake Gases enter/exit by diffusion
down their ?
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Nutrient uptake Gases enter/exit by diffusion
down their ? Ions vary dramatically!
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Nutrient uptake Ions vary dramatically! H is
actively pumped out of cell by P-type H -ATPase
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Nutrient uptake Ions vary dramatically H is
actively pumped out of cell by P-type H
-ATPase and into vacuole by V-type ATPase PPase
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• Nutrient uptake
• H is actively pumped out of cell by P-type H
  -ATPase
• and into vacuole by V-type ATPase PPase
• Main way plants make membrane potential (?Em)!

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• Nutrient uptake
• H is actively pumped out of cell by P-type H
  -ATPase
• and into vacuole by V-type ATPase PPase
• Main way plants make membrane potential (?Em)!
• Used for many kinds of transport!

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Nutrient uptake Many ions are imported by
multiple transporters with varying affinities
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• Nutrient uptake
• Many ions are imported by multiple transporters
  with varying affinities
• K diffuses through channels down ?Em low
  affinity

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• Nutrient uptake
• Many ions are imported by multiple transporters
  with varying affinities
• K diffuses through channels down ?Em low
  affinity
• Also taken up by H symporters high affinity

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• Nutrient uptake
• Many ions are imported by multiple transporters
  with varying affinities
• K diffuses through channels down ?Em low
  affinity
• Also taken up by H symporters high affinity
• Low affinity is cheaper
• but less effective

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Nutrient uptake K diffuses through channels down
?Em low affinity Also taken up by H symporters
high affinity Low affinity is cheaper but less
effective some channels also transport Na
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Nutrient uptake K diffuses through channels down
?Em low affinity Also taken up by H symporters
high affinity Low affinity is cheaper but less
effective some channels also transport Na why
Na slows K uptake?
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Nutrient uptake K diffuses through channels down
?Em low affinity Also taken up by H symporters
high affinity Low affinity is cheaper but less
effective some channels also transport Na why
Na slows K uptake? Na is also expelled by H
antiport
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Nutrient uptake Ca2 is expelled by P-type
ATPases in PM
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• Nutrient uptake
• Ca2 is expelled by P-type ATPases in PM
• pumped into vacuole ER by H antiport P-type

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• Nutrient uptake
• Ca2 is expelled by P-type ATPases in PM
• pumped into vacuole ER by H antiport P-type
• enters cytosol via gated channels

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• Nutrient uptake
• PO43-, SO42-, Cl- NO3-
• enter by H symport

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• Nutrient uptake
• PO43-, SO42-, Cl- NO3- enter by H symport
• also have anion transporters of ABC type

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• Nutrient uptake
• PO43-, SO42-, Cl- NO3- enter by H symport
• also have anion transporters of ABC type
• and anion channels

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• Nutrient uptake
• PO43-, SO42-, Cl- NO3- enter by H symport
• also have anion transporters of ABC type
• and anion channels
• Plants take up N many ways

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• Nutrient uptake
• Plants take up N many ways NO3- NH4 are
  main forms

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• Nutrient uptake
• Plants take up N many other ways
• NO3- also by channels
• NH3 by diffusion
• NH4 by carriers

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• Nutrient uptake
• Plants take up N many other ways
• NO3- by channels
• NH3 by diffusion
• NH4 by carriers
• NH4 by channels

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• Nutrient uptake
• Plants take up N many other ways
• 3 families of H symporters take up amino acids

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• Nutrient uptake
• Plants take up N many other ways
• 3 families of H symporters take up amino acids
• Also have many peptide transporters
• some take up di- tri-
• peptides by H symport

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• Nutrient uptake
• Plants take up N many other ways
• 3 families of H symporters take up amino acids
• Also have many peptide transporters
• some take up di- tri-
• peptides by H symport
• others take up tetra-
• penta-peptides by H symport

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• Nutrient uptake
• Plants take up N many other ways
• 3 families of H symporters take up amino acids
• Also have many peptide transporters
• some take up di- tri-
• peptides by H symport
• others take up tetra-
• penta-peptides by H symport
• Also have ABC transporters
• that import peptides

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• Nutrient uptake
• Plants take up N many other ways
• 3 families of H symporters take up amino acids
• Also have many peptide transporters
• some take up di- tri-
• peptides by H symport
• others take up tetra-
• penta-peptides by H symport
• Also have ABC transporters
• that import peptides
• N is vital!
• NO3- NH4 are main forms

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• Nutrient uptake
• Metals are taken up by ZIP proteins by ABC
  transporters
• same protein may import Fe, Zn Mn!

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Nutrient uptake Much is coupled to pH gradient
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Nutrient transport in roots Move from soil to
endodermis in apoplast
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Nutrient transport in roots Move from soil to
endodermis in apoplast Move from endodermis to
xylem in symplast
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Nutrient transport in roots Move from endodermis
to xylem in symplast Transported into xylem by H
antiporters
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Nutrient transport in roots Move from endodermis
to xylem in symplast Transported into xylem by H
antiporters, channels
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Nutrient transport in roots Transported into
xylem by H antiporters, channels,pumps
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Nutrient transport in roots Transported into
xylem by H antiporters, channels,pumps Lowers
xylem water potential -gt root pressure
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Water Transport Passes water nutrients to
xylem Ys of xylem makes root pressure Causes
guttation pumping water into shoot
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Transport to shoot Nutrients move up plant in
xylem sap
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Nutrient transport in leaves Xylem sap moves
through apoplast Leaf cells take up what they
want
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Photosynthesis Converts light to chemical
energy 6 CO2 6 H2O light energy ltgt C6H12O6
6 O2
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Photosynthesis 2 sets of rxns in separate parts
of chloroplast
113
Photosynthesis 1) Light rxns use light to pump
H use ? pH to make ATP by chemiosmosis
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Photosynthesis 1) Light rxns use light to pump
H use ? pH to make ATP by chemiosmosis 2)
Light-independent (dark) rxns use ATP NADPH
from light rxns to make organics
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Photosynthesis 1) Light rxns use light to pump
H use ? pH to make ATP by chemiosmosis 2)
Light-independent (dark) rxns use ATP NADPH
from light rxns to make organics only link each
provides substrates needed by the other
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Important structural features of
chloroplasts very large organelles 5-10 µm long,
2-4 µm wide
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Important structural features of chloroplasts 3
membranes 1) outer envelope permeable to
molecules up to 10 kDa due to porins
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Important structural features of chloroplasts 3
membranes 1) outer envelope 2) inner
envelope impermeable all import/export is via
transporters
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Important structural features of chloroplasts 1)
outer envelope 2) inner envelope 3) thylakoids
Stromal membranes
120
Important structural features of chloroplasts 3)
thylakoids Stromal membranes a) grana stacks
of closely appressed membranes b) stromal
lamellae single thylakoids linking grana
121
Important structural features of chloroplasts All
cp membranes have MGDG, DGDG SL thylakoids only
have MGDG, DGDG, SL PG thylakoid lipids have
many trienoic fatty acids most fluid membranes
known
122
Important structural features of
chloroplasts Stroma is pH 8.0 in light thylakoid
lumen is lt 5 Stroma is full of protein also
contains DNA genetic apparatus
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Light Rxns 3 stages 1) Catching a photon
(primary photoevent)
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Light Rxns 3 stages 1) Catching a photon
(primary photoevent) 2) ETS
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Light Rxns 3 stages 1) Catching a photon
(primary photoevent) 2) ETS 3) ATP synthesis by
chemiosmosis
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Catching photons photons particles of energy
that travel as waves Energy inversely
proportional to wavelength (?) visible light
ranges from 400 -700 nm
127
Catching photons Photons particles of energy
that travel as waves caught by pigments
molecules that absorb light
128
Pigments Can only absorb certain photons
129
Pigments Can only absorb certain photons Photon
has exact energy to push an e- to an outer orbital
130
Pigments Can only absorb certain photons Photon
has exact energy to push an e- to an outer
orbital from ground to excited state
131
Pigments Photon has exact energy to push an e- to
an outer orbital from ground to excited
state each pigment has an absorption spectrum l
it can absorb
132
Pigments Chlorophyll a is most abundant
pigment chlorophyll a looks green -gt absorbs all
l but green Reflects green
133
Accessory Pigments absorb l which chlorophyll a
misses chlorophyll b is an important accessory
pigment
134
Accessory Pigments absorb l which chlorophyll a
misses chlorophyll b is an important accessory
pigment others include xanthophylls carotenoids
135
Accessory Pigments action spectrum shows use of
accessory pigments l used for photosynthesis
136
Accessory Pigments action spectrum shows use of
accessory pigments l used for photosynthesis plan
ts use entire visible spectrum l absorbed by
chlorophyll work best
137
Light Reactions 1) Primary photoevent pigment
absorbs a photon
138
Light Reactions 1) Primary photoevent pigment
absorbs a photon e- is excited -gt moves to outer
orbital
139
Light Reactions 4 fates for excited e- 1)
returns to ground state emitting heat longer ?
light fluorescence
140
Light Reactions 4 fates for excited e- 1)
fluorescence 2) transfer to another molecule
141
Light Reactions 4 fates for excited e- 1)
fluorescence 2) transfer to another molecule 3)
Returns to ground state dumping energy as heat
142
4 fates for excited e- 1) fluorescence 2)
transfer to another molecule 3) Returns to ground
state dumping energy as heat 4) energy is
transferred by inductive resonance excited e-
vibrates and induces adjacent e- to vibrate at
same frequency
143
4 fates for excited e- 4) energy is transferred
by inductive resonance excited e- vibrates and
induces adjacent e- to vibrate at same
frequency Only energy is transferred
144
4 fates for excited e- 4) energy is transferred
by inductive resonance excited e- vibrates and
induces adjacent e- to vibrate at same
frequency Only energy is transferred e- returns
to ground state