plant transportation/nutrition

Biology V23.0012 with Velhagen at New York University

About this deck

By: Fariya Islam
Textbook:

Biology with MasteringBiology? (with WebCT Access Code Card -- Generic) (8th Edition)
Created: 2011-05-08
Size: 59 flashcards
Views: 30

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nitrogen

essential element for plant growth

rate limited element

perceived as signal in environment

lateral root meristems form in response to nitrogen (low amounts - more lateral roots)

morphometric tool (AAMT)

measure of plasticity of root system in complex/novel environments

root landmarks

captures phenotypes and averages overall responses

principle component analysis

which parameter can account for the most variability?

traits to gene correlation network

engineer increase N-use efficiency in transgenic plants

energy & cost: reduced need for fertilizer
environment: reduce ground water contamination by nitrates
nutrition: increase yield and quality of crops

cellulose scaffolding

cell walls of ligament (strength to stand up) & cellulose (used to make biofuels)

cell walls from corn stalks and other agricultural residue

cellulose fermented into ethanol (used as additive to gasoline for improved performance)

oil producing plants

source of biodiesel

produced from rape, algae, and soybeans are replacing petroleum-derived diesel

(alternative to cellulose biofuel)

energy crops

grown on land not good for traditional crops

transport via leaves

IN:

CO₂, sugar, light

OUT:

O₂, H₂O (transpiration)

transport via roots

IN:

H₂O, minerals (NO₃,K⁺), O₂

OUT:

CO₂

xylem

upward: water/minerals

roots absorb water/dissolved minerals from soil
water/minerals move up from roots to shoots as xylem sap
transpiration: water evaporation (through open stomata) creates major driving force w/in leaves that pulls xylem sap upward

xylem

4. through stomata, leaves take in CO₂ and expel O₂
CO₂ provides carbon for photosynthesis

sugars produced by photosynthesis in leaves

phloem

downward: organic compounds (sugars/amino acids)

6. sugar transported down as phloem sap down to roots/nonphotos. plant parts (SINK)

7. roots exchange gases w/air spaces of soil

take in O₂, discharge CO₂cellular respiration requires breakdown of sugars

transport of water/nutrients in plants on 3 scales

from env. to single cells
water/solutes (nutrients into root epid. hair cells)
short dist: cell-cell
@ tissue/organ level (leaf mesophyll cell into sieve tube/phloem)
long dist: xyl/phl (bulk flow)
plant vasc. systm @ whole plant level (root-leaves)

1) movement of solutes across plasma membrane

diffusion: hydrophobic/small uncharged molecules
facilitated diffusion: charged/large uncharged molecules

active transport: solute move against [gradient] uphills, low to high, ATP required

plasma membrane ATPase proton pumps general dual energy source: proton gradient & membrane potential

proton gradient: ATP to pump H⁺ out of cell, creates hydrogen ion gradient (high H⁺) outside cell

membrane potential: pumping protons out of cell contribute to voltage difference known as membrane potential- separation opposite charges across membrane

membrane potential drives cation uptake into cells (co-transport)

plant cells use energy (voltage) stored in membrane potential to drive transport of cations into cell

membrane potential, cation uptake
co-transport of anion w/H⁺
co-transport of neutral solute w/H⁺

transport driven by proton [gradient]

transport of solutes into cells/[solute] affects water movement into cells

selec. perm. memb.: sugar mol cant pass through pores, water molecule can pass
lower [sugar]: more free water, higher [water]
water clusters around sugar
higher [solute]: fewer free water, lower [water]
water moves from high to low [free water], osmosis

water movement depends on water potential inside cell

psi, MegaPascals

psi = p + s

p = pressure (physical) potential (from cell wall)

positive or negative

s = solute potential (osmotic potential)

pure water = 0 MPa
adding solutes to soln lowers water pot.
always negative for soln (compared to pure water)

addition of solutes reduces water potential

water moves from high water pot. to low water pot.

application of physical pressure increases water potential

positive pressure --> increase positive pressure

water up take makes cell become:

turgid

flaccid cell placed in solution with lower [solute], water move in and cell becomes turgid (@equilibrium with its surroundings)

water movement into guard cells on leaves regulates opening and closing of stomata

transport of K⁺ into guard cells increase [solute], lowering water pot. and effecting influx of water into guard cells

influx of water into guard cells causes increase in turgor pressure of guard cells causing them to open

hypotonic solution

too few solutes

animal: lysed

plant: turgid (normal)

isotonic solution

animal: normal

plant: flaccid

hypertonic solution

too many solutes

animal: shriveled

plant: plasmolyzed

2) cell-cell transport of solutes: 3 routes @tissue level (TSA)

tranmembrane route
symplastic route- continuum of cytosol connected by plasmodesmata

apoplastic route- continuum of cell walls and extracellular spaces

cell-to-cell lateral transport of minerals and water in roots

1) soil solution uptake by hydrophilic walls of root hairs - provides access to the apoplast (extracellular cell wall), no selectivity

2) plasma membrane selective regulates transport of minerals into symplast

cell-to-cell lateral transport of minerals and water in roots

3) soil moves along apoplast & some water/minerals transported into symplast

4) casparian strip (waxy layer) in endodermis forces solutes to pass through a selective cell membrane to regulate minerals transported into xylem

casparian strip

acts as gatekeeper since dead cells have no power of

3) long distance: xylem/phloem (bulk flow)

xylem: dead conducting tubes

main driving force: transpiration (water evaporation)

thin xylem vessels: capillary action

upward ascent of fluid in xylem sap via transpiration/cohesion/adhesion

1) transpiration: major force

2) water cohesion (b/w water molecules) and adhesion (to cell wall) in xylem (by H bonding)

soil water potential > leave water potential

"loading" of sugar into phloem sieve cells = apoplastic active transport

phloem: live conducting tubes, bulk flow (ATP)

phloem loading: transport sucrose into phloem against [gradient] using ATP
accumulates in phloem against a [gradient]

apoplast/cell wall - low [sugar]

symplast/in phloem cell - high [sugar] > 1M sucrose

phloem 2 cell types

sieve tube- cell walls w/holes, alive to transport sugars to companion cell, down against [gradient] into phloem (loading)
companion cell- normal cell lose nucleus, keep cytoplasm, mRNA transport into cell from companion cell (keep e-nucl cell alive)

phloem loading

leaf=source (makes sugar)

root=sink (needs sugar)

if transported symplastically into sieve, laws of diffusion followed - wouldn't make high enough [ ] in sieve

sucrose goes into apoplast + pumped into sieve by plasma membrane ATPase

pressure flow: mechanism of translocation in phloem

source cell: leaf mesophyll

C-source: photosynthesis

1) sugar loaded into phloem, reduces water potential causing water uptake in sieve by osmosis

2) water uptake +pressure, forces sap to flow along tube (faster than diffusion or cytoplasmic streaming)

pressure flow: mechanism of translocation in phloem

sink cell (root): non-photosynthetic

C-storage: leave

3) sugar upload into root sink cell causes lower solute potential in phloem and loss of water from phloem

4) water recycled by xylem back to source (leaves)

essential elements in plants

macronutrients - needed in large quantities
C, O, H, N, K, Ca, Mg, P, S

micronutrients - needed in small quantities

Cl, Fe, B, Zn, Cu, Ni, Mn, Molybdenum Mo

hydroponics to determine essential

plant roots bathed in aerated solutions of known mineral composition

one mineral omitted

essential for growth: deficiency symptoms occur (stunted growth, discolored leaves)

deficiencies in diff. elements may have diff. symptoms - aid in diagnosis

most common elemental deficiencies

color patterns

healthy - green
phosphate deficient - purple
potassium deficient - orange/yellow
nitrogen deficient - yellow

acids derived from roots contribute to uptake of minerals

mineral cations (+) bind to (-) charged soil

carbonic acid --> dissociation adds H⁺ to soil which displaces mineral cations from clay particles
acidification of soil makes cations available for uptake by roots

environmental issue

anions (like NO3-) leach into ground water because they do not bind to soil
^ environmental issue

minerals available to plants: ecosystems v. agriculture

natural ecosystems- (forests) soil minerals obtained from decaying plants

agriculture- growth of large # of crop plants in same soil/harvesting of crop: depletes mineral content of soil

farmers replace minerals in soil w/fertilizer

commercial v. organic

commercially produced fertilizers

have minerals that are mined or prepared by industrial processors
rapid release of minerals to soil (+)
minerals "leach" into and contaminate ground water (+)
problem for (-) charged minerals (nitrate) that do not bind to (-) charged soil

organic fertilizers

composed of manure, fishmeal, or compost
decay slowly - "time release" of minerals
less leaching

soil bacteria + nitrogen availability

nitrogen fixing soil bacteria- convert atmosphere N₂to nitrogenous minerals (plants can absorb as N source for organic synthesis)

have nitrogenase enzyme- reduce N to NH₄(nonsterilized plants grow better), NH₄ denitrified into N₂ or taken up by plant

development of soybean root nodule

1) roots emit chemical signals that attract Rhizobium bacteria which emits signals that stimulate root hairs to elongate and form an infection thread by an invagination of the plasma membrane

development of soybean root nodule

2) bacteria penetrates cortex w/in infection thread
cells of cortex + pericycle begin dividing and vesicles containing bacteria bud into cortical cells from branching infection thread
results in formation of bacterioid

development of soybean root nodule

3) growth continues in affected regions of cortex/pericycle, 2 masses of dividing cells fuse and form the nodule

development of soybean root nodule

4) nodule develops vascular tissue that supplies nutrients (sugar) to nodule and carries nitrogenous compounds into vasc. cylinder for distributions throughout plant

legume plants associate w/soil bacteria called Rhizobium that live inside plant root cells forming root nodules

legumes have root swilling called nodules- plant cells infected by nitrogen fixing Rhizobium bacteria

symbiotic nitrogen fixation & agriculture

crop rotation

- one year: non-legume (maize) planted

- next year: legume (Alfalfa) planted

-legume associates w/Rhizobium (fix atmospheric N₂ into ammonium)

-alfalfa tilling back into soil restores [soil nitrogen]

- reduces need for commercial fertilizer

plants & human nutrition & use

transgenic plants

genetic manipulation of plants

- plant breeders

- maize product of artificial gene selection

- staple in developing countries by poor source of protein

essential amino acids

from plants

engineer storage protein w/all essential amino acids

agrobacterium: naturally occurring gene transfer system to make transgenic placts

1) TDNA in Ti plasmid + bacterial chromosome (A. tumefaciens)

2) infection of plant cell and integration of DNA

TDNA codes for enzymes that mimic hormones - leads to tumor growth - genes induce amino acid production

Agrobacterium tumefaciens technique

Ti plasmid

site where restriction enzyme cuts

DNA with gene interest put into plasmid -- recombinant Ti plasmid

plasmid put back in agrobacterium

results in plant w/new trait

genetically modified plants: potential of to increase quality/quantity of food worldwide

- genetically modified papaya w/gene conferring resistance to ring spot virus

- genetically modified golden rice have inserted genes to produce vitamin A in rice seeds (deficiency causes blind

types of useful transgenes to put into CROP plants

1) improve nutrition of taste

golden rice: gene for carotenoid biosynthesis (vitA), tomato, higher starch potato

2) improve yield

insect resistance: BT toxin gene put in
virus resistance: salt/freezing tolerance

herbicide (weed) resistance

3) novel products

debate

human health:

transfer allergens from gene source to food plant

environment:

risks of GMorganisms release into environment

effects of BTtoxin on non-target organisms

transgenic pollen spread transgene to non-transgenic crops or to hybridizing weeds

About this deck

By: Fariya Islam
Textbook:

Biology with MasteringBiology? (with WebCT Access Code Card -- Generic) (8th Edition)
Created: 2011-05-08
Size: 59 flashcards
Views: 30

About StudyBlue

“I have been getting MUCH better grades on all my tests for school. Flash cards, notes, and quizzes are great on here. Thanks!”
Kathy