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Flashcards in Solute transport Deck (32):
1

ion diffusion is driven b y

chemical potential difference x membrane permeability

2

chemical potential difference is driven by differences in --

concentration, pressure, and electric potential (voltage)

3

-- are large driving forces

concentration and voltage differences

4

at equilibrium, there may remain a -- as well as a small concentration gradient across the membrane

membrane potential (voltage difference)

5

a substantial voltage difference may be generated even though the number of unbalanced ions is --

negligible

6

a membrane potential of -- may be generated by a concentration difference across the membrane of 0.001%

-100 mV

7

all living cells exhibit a membrane potential due to the -- between the inside and outside of the cell

asymmetric ion distribution

8

membrane potential can be determined by -- the cell and external solution with microelectrodes

probing

9

Nerst equation gives the -- expected across a membrane at equilibrium if the voltage across the membrane is known

concentration gradient

10

Goldman equation predicts the diffusion potential from Na+, K+, Cl_ the ions with the -- cellular concentrations

highest

11

for most ions, experimentally determined ion concentrations differ from Goldman equation prediction indicating --

active transport

12

cytosol and -- differ strongly in ion uptake

vacuole

13

-- is taken up passively by both cytosol and vacuole unless concentration is very low, then it is taken up actively

K+

14

Na+ and Ca2+ and excess protons are -- out of the cytosol into the vacuole and extracellular spaces

actively pumped out

15

anions are -- into the cytosol

actively taken up

16

effects of ATP can be provided by using -- to poison mitochondria, which depletes ATP

CN-

17

when CN- is added to cell, the membrane potential falls to that -- by the Goldman equation (also cytosol becomes acidic because H+ remains in cell)

predicted

18

facilitate the passage of selected ions and other polar molecules

transport proteins (transporters)

19

in arabidopsis, about -- of all genes code for transporters

5%

20

can be specialized to only allow one direction ion movement

channels

21

carrier mediated transport is --

passive or active

22

secondary active transport can be --

symport or antiport

23

vacuole has a low pH relative to the cytoplasm

hyperacidic

24

rate of ion uptake =

rate of protein activity

25

Michaelis-Menten kinetics: rate of ion uptake plotted against --

ion concentratio

26

A saturation (Michaelis-Menten) curve appears

rate increase and then stabilizes

27

max rate of uptake

Vmax

28

ion concentration to drive 50% to Vmax

Km

29

low Km

high affinity

30

ions are mostly absorbed through --

root hairs

31

at endodermis, the ions but enter the -- because of the suberized Casparian strip

symplast

32

casparian strip control ion entering xylem and prevents -- out of xylem to the soil via apoplast

diffusion of ions