SOLUTE TRANSPORT Flashcards
Chemical potential
the sum of the concentration, electrical and hydrostatic potentials
energy of substance to perform freely work
Diffusion
movement of molecules or atoms from a region of high chemical potential to low chemical potential
Influx –> inside
Efflux –> outside
Facilitated diffusion *
involves in the movement of specific molecule (ions)
specific channels or carrier proteins
needs no ATP energy (passive diffusion)
chemical potential gradient
Glucose transporter
glucose permease
Equilibrium
reached when these two forces completely counteract, at which point the net movement of charged ions is zero
Electric field
balances the concentration gradient in activity of i
Facilitated diffusion of “i”
“i” interacts with a molecules in the membrane to permit its passive diffusion down its chemical potential gradient
Nernst equation
RT ln aiO =(EC -EO)=ΔE=Em
ziF. aiC
Unit=V (voltage)
Nernst potential
electrical potential at the equilibrium condition
Measurement of Jk influx and efflux
Using the radioisotope to measure unidirectional fluxes
Measurement of membrane potential
microelectrodes
Antiporter
carries two different ions or molecules but in different direction
Symporter
carries two different ions or molecules both in the same direction
H+ pumping ATPase
primary active transport system
pumping protons out of the cell: production of electric and pH gradients
Blue light
Guard cell osmotic adjustment
mediated by accumulation of
K+ and malate/Cl-
sucrose from starch or photosynthesis
Blue light
stimulates H+ ATPase
Guard cell
Stomata open: H+ out, K+ and H2O in
guard cell= turgid
Stomata closed: Cl-, K+, H2O out
guard cell=flaccid
Guard cell opening
Blue light
Starch degradation and malate synthesis and H+ ATPase stimulated
Increasing level of sucrose and malate
H+ pumping out of guard cells
Accumulation of sucrose, malate, K+ and Cl+
Guard cell opening
Lower solute potential
Decrease water potential
Water uptake
Stomata open
Guard cell closing
conversion of sucrose to starch –> decreasing level of sucrose and malate
H+ATPase stopped –> open outward channels of K+ and Cl- and K+ and Cl- exit across membrane
Guard cell closing
water solute increases
water potential increases
water loss
stomata closed
