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87 Cards in this Set

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Totipotent
one plant cell can be regenerated into an entire plant
Membrane: Definition and Function
Lipid bilayer with proteins surrounding the protoplast.
Acts as a boundary, controlling transport of compounds in and out
Selectively Permeable
Membrane is able to control what goes in and out and how fast it does
Location and Function of Endoplasmic Reticulum
Around the nuclear envelope.
Protein and lipid synthesis
Ribosomes
Site of protein (mRNA are translated)
Can be free or attached to E.R,
Symplast
Long string of connected cell cytoplasma via plasmadesmata. Allows for easy flow of substances (once in, can go anywhere)
Apoplast
Large area outside of the cell membrane, including the cell wall.
Epidermis
Outermost cell layer. Serves as a form of protection (waxy cuticle) and site of gas exchange
Parenchyma
Ground tissue that makes up most of the body of the plant.
Supporting Tissues
collenchyma (young tissue in primary wall)
sklerenchyma (secondary wall
Vascular Tissues
Involved in long distance transport
Xylem and Phloem
Xylem
Formed from dead cell walls (hallow structure with no membrane barriers). Used to transport water and minerals from roots to shoots.
Phloem
Formed from living sieve cells. Transports sugars and other compounds from mature leaves to other plant parts where they are needed
3 layers of a leaf
Epidermis
Mesophyll
Vascular Tissues (xylem and phloem)
Peroxisome
A microbody used for detoxification
Glyoxysome
Microbody used to breakdown fats
Cytoskeleton
Network of protein fibers throughout the cell.
Used for support and movement.
Sections of a root
Epidermis
Cortex
Endodermis
Phloem/Xylem
How much of a plant is water?
Dry matter?
What is the majority of dry matter made of?
70-95%
5-30%
H, O, N, C (96%)
Why do plants need water?
1. Source of H and O
2. Good solvent (transport and reactions)
3. Support
Adhesion and Cohesion
Adhesion: binging to polar surfaces
Cohesion: binging to each other (molecules)
What are the two forms of water movement?
When are each used?
Osmosis (diffusion driven). Short distance movement over a membrane.
Bulk Flow (pressure driven) Can be long-distance, usually with no membranes present
Hypotonic, Hypertonic, and Isotonic
Which direction will water move?
Hypotonic: lower [ ] in solute; higher water potential; into cell
Hypertonic: higher [ ] in solute; lower potential; out of cell
Isotonic: [ ]s are equal
Osmotic Pressure
Pressure needed to prevent a volume increase of a solution that tends to take up water via osmosis.
>0, increases with [ ]
Osmotic Potential
Potential of a solution to attract water via osmosis, and this to exert pressure
<0, becomes more negative with [ ]
The osmotic potential of a cell is mostly determined by...(organ)
the vacuole, 80% of cell volume so holds most solutes.
Usually btw -0.1 to -0.5 Mpa
Osmosis is driven by
Concentration and Pressure
Pressure Potential
Pressure exerted on container walls (cell wall) by expanding solution that is taking up water via osmosis. Turgor Pressure
>0
Water Potential
total driving force for water movement via osmosis.
Ψ = Ψp + Ψs
Water will always move from highest to lowest water potential until equilibrium
Limp cell w/ Ψs -0.7 in a solution open to the air with Ψs -0.9. What is new Ψp, Ψs, and Ψ of cell? What way did water move?
Ψp = 0
Ψs = -0.9
Ψ = -0.9
Water moved out of cell
Limp cell w/ Ψs -0.7 in a distilled water open to the air. What is new Ψp, Ψs, and Ψ of cell? What way did water move?
Ψp = 0.7
Ψs = -0.7
Ψ = 0
Water moved into cell
At equilibrium Ψ(solution) ______ while Ψ(cell) ______. In the cell, Ψs _______, while Ψp ______.

Changes/Does not change
does not change
changes
does not change
changes (due to osmosis)
Pressure bomb, Psychrometer and "weight change" measure...
Water Potential
Root to shoot transport
xylem
Shoot to root transport
phloem
Phloem sap should be collected ______ while xylem sap should be collected from ______.
The leaf
The stem
Xylem is part of the ______ and phloem is part of the _______.
Apoplast
Symplast
Why do plants transpire?
1. to bring water to shoot
2. to bring mineral to shoot
3. cools the leaves
4. necessary evil for CO2 intake
Lysimeter and Potometer measure
Transpiration
What step are taken in transpiration?
1. Uptake into root syplast. Passes membrane #1 in solute-driven osmosis.
2. Export into root xylem apoplast. Passes membrane #2 in pressure-driven osmosis
3. Bulk flow to shoot. Adhesion and cohesion (no membrane or osmosis).
4. Uptake in shoot symplast. Passes membrane #3 in solute-driven osmosis
5. Evaporation into air. Passes membrane #4 in pressure-driven osmosis.

If starts off by entering into apoplast rather than symplast, it needs to go through one more membrane in the endodermis before entering the xylem.
Solute or Pressure driven Osmosis?
Into a cell=solute
Out a cell=pressure
Cavitation
Air bubble in xylem form from dissolved gas under tension or low temp. Blocks transport in vessel, causing lateral movement of water around the air bubble via pits (old plasmadesmota)
Acclimation vs Adaptation
Acclimation: metabolic/morphlogic changes in an individual (short-term response)
Adaptation: long-term genetic response
What aspects of the environment affect transpiration?
1. Humidity (lower humidity, the higher the water potential, the more transpiration)
2. Temperature (higher temp, more transpiration)
3. Wind (more wind reduces the boundary layer, reduces diffusion path for water molecules, increases transpiration)
What aspect of soil influences water availability?
Soil structure. Affects porosity, water retention and aeration
Permanent Wilting Point
When soil Ψ is so low that plants are not able to take up water
Soil Ψ is base on...
Pressure since [ ] is relatively low
Field Capacity
soils with moisture left in capillary pores after drainage
Available water =
Field capacity - permanent wilting %
Root hairs
outgrowths of epidermal cells that increase root surface. Able to reach capillary pores in soil.
Macronutrients
P, K, Ca, Mg, S
Structural
Micronutrients
Fe, Zn, Mn, Cu, B, Cl, Ni, Mo
Catalytic/regulatory role
Hydroponics and Film Technique are used to study
Plant Nutrition
Symptoms of Deficiency
Chlorosis
Necrosis
Stunted Growth
Deformity
Critical Concentration
Plant tissue concentration of an element just below the level that gives max growth
Deficient Concentration
Tissue concentration below the critical concentration (growth is limited by element)
Adequate Concentration
Tissue concentration above the critical concentration (growth doesn't increase with [ ] increase)
If an element is mobile ______.
Where does remobilization take place?
symptoms will appear in older leaves first.
Phloem, symplast
Critical Toxicity Level
Tissue concentration that gives a 10% reduction in dry matter
Na, Si, Se, Co
Na: C4, CAM plants
Si: Grasses
Se: Hyperaccumulators
Co: Legumes
How does soil affect nutrient availability?
1. Provides nutrients through weathering
2. Binds minerals reversibly (CEC)
Colloids
Particles that remain in suspension b/c negative changes attract polar water molecules (clay and humus)
Cations usually _____ to soil while anions ______ soil.
How does acidity affect bioavability?
Bind
Leach
More acidic soils (lower pH) mean more H+ are available to engage in CEC and replace cations on soil surface
Mineral uptake by roots
May be passive or active (protein).
1. Diffuses through root apoplast btw epidermis and endodermis (active or passive)
2. Pass membrane and enter endodermis symplast (active)
3. Exported into xylem apoplast (active)
How can plants make a mineral more bioavailable?
1. Secret H+
2. Secret chelators
3. Symbiosis with soil microbes
Chelator Strategy I
Phenolic compund secreted by root chelates ion and brings it to root surface. Enzyme in root membrane reduces ion, which is then release by phenol and taken in by membrane carrier
Chelator Strategy II
Phytosiderophores secreted by root chelate ion and brings it to root surface where entire complex it taken up. Ion is the reduced inside and released.
Rhizosphere
~1mm area around roots
Mycorrhizae
Symbiotic fungi that live in roots of 90% of plant species
What happens to a mineral once it enters the plant?
1. Export to root xylem apoplast (membrane, active transport)
2. Bulk flow to shoot (driven by transpiration)
3. Uptake in shoot symplast (membrane, active import)
What are the types of passive protein transport? (3)
1. Through bilayer (not specific)
2. Through channel (not specific)
3. Via carrier (specific)
Symport vs. Antiport
Direction of ion in relation to cotransport
Symport: same direction of H+
Antiport: opposite direction of H+
Which areas of a cell have a more negative membrane potential?
A more positive?
Cytosol = -
Apoplast/outside and vacoule = +
Secondary Transport
After a proton pump push H+ out, H+ wants to come back in (con. grad.). As it does so, it acts as a cotransport and brings in another ion. Although this step requires NO ATP, it would not happen without the primary pump's action
N Assimilation
N2 in air ------ NH4 --- NO2 -----NO3
N-fixing bact. nitrifying b. plants
How does a plant create a nodule?
1. Plant exudes signal molecules
2. Bacterium responds with signal molecules
3. Plant responds with altered root growth
4. Bacterium grows into plant tissue, between cells
5. Plant form nodule around bacteria
Nod factors
Bacterial response to plant's signal to form a nodule
Leghemoglobin
Protein that controls O2 levels in plant (affects dinitrogenase)
S Assimilation
SO4 --- SO3 ---- S ---- cysteine
Substrate
Reactant that an enzyme uses. Binds to active site on an enzyme
Enzyme
Proteins that act as biological catalysts
Active Site
Location where substrate binds to enzyme
Enzyme reaction rate in influenced by
1. Cofactors
2. Inhibitors
3. Activators
Cofactors
Non-protein molecule required for enzyme activity
Inhibitors
Competitive: binds to active site
Non-competitive: binds in allosteric site, which changes shape thus not allowing substrate to bind
Activators
Activates enzyme through binding at allosteric site
Transcription Factors
Determines whether or not an enzyme is coded for during transcription in protein synthesis