Lecture 3 - Osmosis and Hydrostatic pressure Flashcards
Important mechanisms for water movement in plants
Osmosis
Turgor pressure
Plasmolysis
the solute potential is _____ when solutes are added to an aqueous system
reduced
osmosis
phenomenon of water flow across a semi-permeable membrane
how does concentration even out if sucrose cannot pass through the membrane
water can pass through, so it evens out through osmosis
what do plants use to regulate pressure potential
solutes
what is the typical pressure inside a cell
0.5-1.5 MPa
how does a plant cell prevent bursting or deformity
rigidity of plant cell wall prevent the osmotic lysis by hydrostatic pressure
plasmolyzed
vacuole shrinks because water moves out
hypertonic
water moving out of the cell
isotonic
water moves in and out of the cell equally (no pressure)
flaccid
no pressure in the vacuole
hypotonic
water moves into the cell
turgid
vacuole expands from water moving in
turgor pressure
pressure from fluid within the cell pushing agianst the cell wall
what are aquaporins used for
used for water transport through the plasma membrane and water movement in cells
expression of aquaporins _______ water uptake
accelerates
how does water move through the aquaporin
water diffuses through pore
water is pulled through channel by cohesion
pressure increase to match solute potential until equilibrium is reached
no more water moves in
tetrameric arrangement
each monomer forms a water channel
how do aquaporins open and close
through phosphorylation and pH
how does a aquaporin close in drought conditions
it is dephosphorylated
how does a aquaporin close in flood conditions
drops the pH value by attracting more H+ ions
in what state does a aquaporin remain open
when it is phosphorylated
