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87 Cards in this Set
- Front
- Back
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Totipotent
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one plant cell can be regenerated into an entire plant
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Membrane: Definition and Function
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Lipid bilayer with proteins surrounding the protoplast.
Acts as a boundary, controlling transport of compounds in and out |
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Selectively Permeable
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Membrane is able to control what goes in and out and how fast it does
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Location and Function of Endoplasmic Reticulum
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Around the nuclear envelope.
Protein and lipid synthesis |
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Ribosomes
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Site of protein (mRNA are translated)
Can be free or attached to E.R, |
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Symplast
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Long string of connected cell cytoplasma via plasmadesmata. Allows for easy flow of substances (once in, can go anywhere)
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Apoplast
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Large area outside of the cell membrane, including the cell wall.
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Epidermis
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Outermost cell layer. Serves as a form of protection (waxy cuticle) and site of gas exchange
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Parenchyma
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Ground tissue that makes up most of the body of the plant.
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Supporting Tissues
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collenchyma (young tissue in primary wall)
sklerenchyma (secondary wall |
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Vascular Tissues
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Involved in long distance transport
Xylem and Phloem |
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Xylem
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Formed from dead cell walls (hallow structure with no membrane barriers). Used to transport water and minerals from roots to shoots.
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Phloem
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Formed from living sieve cells. Transports sugars and other compounds from mature leaves to other plant parts where they are needed
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3 layers of a leaf
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Epidermis
Mesophyll Vascular Tissues (xylem and phloem) |
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Peroxisome
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A microbody used for detoxification
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Glyoxysome
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Microbody used to breakdown fats
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Cytoskeleton
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Network of protein fibers throughout the cell.
Used for support and movement. |
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Sections of a root
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Epidermis
Cortex Endodermis Phloem/Xylem |
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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%) |
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Why do plants need water?
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1. Source of H and O
2. Good solvent (transport and reactions) 3. Support |
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Adhesion and Cohesion
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Adhesion: binging to polar surfaces
Cohesion: binging to each other (molecules) |
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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 |
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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 |
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Osmotic Pressure
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Pressure needed to prevent a volume increase of a solution that tends to take up water via osmosis.
>0, increases with [ ] |
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Osmotic Potential
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Potential of a solution to attract water via osmosis, and this to exert pressure
<0, becomes more negative with [ ] |
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The osmotic potential of a cell is mostly determined by...(organ)
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the vacuole, 80% of cell volume so holds most solutes.
Usually btw -0.1 to -0.5 Mpa |
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Osmosis is driven by
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Concentration and Pressure
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Pressure Potential
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Pressure exerted on container walls (cell wall) by expanding solution that is taking up water via osmosis. Turgor Pressure
>0 |
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Water Potential
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total driving force for water movement via osmosis.
Ψ = Ψp + Ψs Water will always move from highest to lowest water potential until equilibrium |
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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?
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Ψp = 0
Ψs = -0.9 Ψ = -0.9 Water moved out of cell |
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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?
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Ψp = 0.7
Ψs = -0.7 Ψ = 0 Water moved into cell |
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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) |
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Pressure bomb, Psychrometer and "weight change" measure...
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Water Potential
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Root to shoot transport
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xylem
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Shoot to root transport
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phloem
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Phloem sap should be collected ______ while xylem sap should be collected from ______.
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The leaf
The stem |
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Xylem is part of the ______ and phloem is part of the _______.
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Apoplast
Symplast |
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Why do plants transpire?
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1. to bring water to shoot
2. to bring mineral to shoot 3. cools the leaves 4. necessary evil for CO2 intake |
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Lysimeter and Potometer measure
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Transpiration
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What step are taken in transpiration?
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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. |
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Solute or Pressure driven Osmosis?
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Into a cell=solute
Out a cell=pressure |
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Cavitation
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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)
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Acclimation vs Adaptation
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Acclimation: metabolic/morphlogic changes in an individual (short-term response)
Adaptation: long-term genetic response |
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What aspects of the environment affect transpiration?
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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) |
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What aspect of soil influences water availability?
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Soil structure. Affects porosity, water retention and aeration
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Permanent Wilting Point
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When soil Ψ is so low that plants are not able to take up water
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Soil Ψ is base on...
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Pressure since [ ] is relatively low
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Field Capacity
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soils with moisture left in capillary pores after drainage
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Available water =
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Field capacity - permanent wilting %
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Root hairs
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outgrowths of epidermal cells that increase root surface. Able to reach capillary pores in soil.
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Macronutrients
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P, K, Ca, Mg, S
Structural |
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Micronutrients
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Fe, Zn, Mn, Cu, B, Cl, Ni, Mo
Catalytic/regulatory role |
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Hydroponics and Film Technique are used to study
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Plant Nutrition
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Symptoms of Deficiency
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Chlorosis
Necrosis Stunted Growth Deformity |
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Critical Concentration
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Plant tissue concentration of an element just below the level that gives max growth
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Deficient Concentration
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Tissue concentration below the critical concentration (growth is limited by element)
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Adequate Concentration
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Tissue concentration above the critical concentration (growth doesn't increase with [ ] increase)
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If an element is mobile ______.
Where does remobilization take place? |
symptoms will appear in older leaves first.
Phloem, symplast |
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Critical Toxicity Level
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Tissue concentration that gives a 10% reduction in dry matter
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Na, Si, Se, Co
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Na: C4, CAM plants
Si: Grasses Se: Hyperaccumulators Co: Legumes |
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How does soil affect nutrient availability?
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1. Provides nutrients through weathering
2. Binds minerals reversibly (CEC) |
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Colloids
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Particles that remain in suspension b/c negative changes attract polar water molecules (clay and humus)
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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 |
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Mineral uptake by roots
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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) |
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How can plants make a mineral more bioavailable?
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1. Secret H+
2. Secret chelators 3. Symbiosis with soil microbes |
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Chelator Strategy I
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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
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Chelator Strategy II
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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.
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Rhizosphere
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~1mm area around roots
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Mycorrhizae
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Symbiotic fungi that live in roots of 90% of plant species
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What happens to a mineral once it enters the plant?
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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) |
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What are the types of passive protein transport? (3)
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1. Through bilayer (not specific)
2. Through channel (not specific) 3. Via carrier (specific) |
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Symport vs. Antiport
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Direction of ion in relation to cotransport
Symport: same direction of H+ Antiport: opposite direction of H+ |
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Which areas of a cell have a more negative membrane potential?
A more positive? |
Cytosol = -
Apoplast/outside and vacoule = + |
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Secondary Transport
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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
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N Assimilation
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N2 in air ------ NH4 --- NO2 -----NO3
N-fixing bact. nitrifying b. plants |
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How does a plant create a nodule?
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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 |
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Nod factors
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Bacterial response to plant's signal to form a nodule
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Leghemoglobin
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Protein that controls O2 levels in plant (affects dinitrogenase)
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S Assimilation
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SO4 --- SO3 ---- S ---- cysteine
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Substrate
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Reactant that an enzyme uses. Binds to active site on an enzyme
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Enzyme
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Proteins that act as biological catalysts
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Active Site
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Location where substrate binds to enzyme
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Enzyme reaction rate in influenced by
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1. Cofactors
2. Inhibitors 3. Activators |
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Cofactors
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Non-protein molecule required for enzyme activity
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Inhibitors
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Competitive: binds to active site
Non-competitive: binds in allosteric site, which changes shape thus not allowing substrate to bind |
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Activators
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Activates enzyme through binding at allosteric site
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Transcription Factors
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Determines whether or not an enzyme is coded for during transcription in protein synthesis
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