Plant Phys Exam 1

When did the first angiosperms evolve

130 MYA

when did grasses evolve

30-50 MYA

what delayed the movement of plants onto land

avoiding desiccation - not drying out

when did first land plants evolve

500 mya

primary growth

occurs in meristematic tissues

secondary growth

uses two lateral meristems, the vascular cambium and cork cambium

roots

anchorage, uptake of water and mineral ions

stems

support, nodes for growth points, vascular tissue

leaves

gas exchange, vascular tissue

cell wall

provides immense strength to plants

chloroplast

each cell has can have several, where photosynthesis takes place

large central vacuole

used for storage and ion/water absorption; plays major role in cell turgidity

plastids

unique organelles in plants

plasmodesmata

produces a link between cytosol of neighboring cells that allows for solute transfer

vacuole

occupies 50-98% of the cell

tonoplast

membrane that surrounds the central vacuole

storage compounds in vacuole

ions, sucrose, and secondary metabolites that maintain cell turgidity

primary cell wall

thin and flexible layer that is mostly cellulose

secondary cell wall

rigid and provides support, more lignin

middle lamella

the glue that binds cells together

gametophyte

generation that begins with meiosis

sporophyte

generation that begins with fertilization

gravity

weak force but governs the entire universe

electromagnetic

the attractive or repulsive force between electric charges and magnets

strong nuclear

exist to hold protons and neutrons together

weak nuclear

can change a neutron to a proton -> changes element

electromag, w. nuclear, and s. nuclear

all connected together

1st law of thermodynamics

Energy cannot be created or destroyed

2nd law of thermodynamics

measure of the capacity of a system to undergo change, the entropy of the universe is always increasing, and the universe trends towards chaos and disorder

3rd law of thermodynamics

the law that states that in order for motion to stop we have to reach absolute zero

Gibbs free energy

biological rxns require energy and total energy = G

Gibbs free energy equation

ΔG = ΔH - TΔS

exergonic rxn

energy releasing; K > 1

endergonic rxn

Energy requiring; K < 1

spontaneous rxn

G is -

nonspontaneous rxn

G is +

oxidation

addition of O, removal of H, removal of e, displacement of e

reduction

removal of O, addition of H, addition of e, displacement of e

photosynthesis

a series of Redox rxns (water oxidized, CO2 reduced)

enzymes

modified proteins that aren't changed by rxn

enzyme catalyzed rxns

high specificity, high rxn rates, mild rxn conditions, opportunity for regulation

unique properties of water

universal solvent, polarity, high specific and latent heat, high cohesion, high adhesion, high surface tension

universal solvent

results from size and polarity

polarity

H-O-H covalently bonded, opposite bonds resulting in H bonding

high cohesion

polarity results in attraction between H2O; high tensile strength permits capillary action

high adhesion

attraction of water to solid phase

high surface tension

water prefers water not other gasses, energy is required to incr. surface area of gas-water interface

diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration over a short distance (cellular)

mass flow

movement of groups of molecules in response to a pressure gradient (environmental gradient)

osmosis

Diffusion of water through a selectively permeable membrane

water potential

free energy of water per unit volume (Jm-3 or Pa)

water potential equation

Ψw = Ψp+Ψs+Ψg

osmotic potential Ψs

more solutes = less energy; dilution effect; only ever negative, Ψs = 0 then pure water

hydrostatic pressure potential Ψw

can be + or -, + = turgor, - = tension

gravitational potential Ψg

grav. is true force acting on water, increase height incr. Ψg by 0.1 MPa per 10 m

turgor

pushing potential (+)

tension

pulling potential (-)

turgor potential

has greater potential decline w/ initial decr. in cell volume

elastic modulus

the slope of Ψp - V curve in cells

less water/turgidity

higher ion conc and lower Ψs

pressure potential

directly linked to osmotic potential

dessication

some species can recover, but most can't due to tears in membrane and inability to recover cell contents

plasma membrane

semipermeable membrane that regulates molecule and ion movement in and out of cell

phosopholipid

hydrophilic head and hydrophobic tail

bilayer structure

results in a highly fluid, very stable, and impermeable membrane

transport

movement of molecules and ions across a membrane or w/in or between cells

passive transport

spontaneous movement down a potential energy gradient (diffusion/osmosis/mass flow) and proceeds until equilibrium

active transport

against conc. gradient, not spontaneous and requires energy

ATP synthase

enzyme that uses protons to perform ATP synthesis

proteins

membranes can have >= 50%, have lateral fluidity

primary role of membrane proteins

metabolism, transport, energy transduction

transport proteins

channels, carriers, and pumps

channels

passive transport, can open and close. Low pH—> high pH

carriers

switch between active and passive transport (anti- and sym- porters). PMF

pumps

active transport that move ions against gradient. High pH—> low pH. Atp hydrolysis

confirmational binding

change of structure of carriers and pumps depending on the molecule theyre transporting

proton motive force

secondary active transport, conc. of H outside the cell creates an electrochemical energy and pH gradient

symporters

both ions/molecules travel in the same direction (PMF)

antiporters

ions/molecules move in opposite directions (PMF)

vacuole

takes up ions so they don't interfere w/ organelles; water follows ions to help maintain cell turgidity

cytosol

has a neutral pH to ensure proper organelle function; have higher conc. of sugars, amino acids, and metals to be available for use

aquaporins

channel proteins that facilitate water movement across membranes (gated channel), allows water to move much faster than just diffusing across membrane

slowest -> fastest membrane transport

pump -> carrier -> channel

apoplast

cell wall space between adjoining cells (5-20% of plant)

symplast

cell-cell transport between plasmodesmata

Casparian strip

a barrier to all apoplastic movement and water/ions must be allowed into symplast to continue forward. keeps water from experience reverse flow in drought conditions.