Chapter 3

Question 1

Most plant transporter genes are members of _______________ ____________ that show developmental and tissue-specific expression.

Answer 1

multigene families

Question 2

Central functions of membrane transporters in response to physiological stimuli including abiotic and biotic __________ and how the activities of individual transporters are coordinated within a network at the cell and tissue levels.

Answer 2

stresses

Question 3

MEMBRANES FACILITATE ______________________!!!!!

Answer 3

COMPARTMENTALIZATION!!!!

Question 4

___________ displays anomalously high permeability in biological membranes.

Answer 4

Water

Question 5

Compartmentalization of ______________ within membrane-bound organelles not only concentrates reactants and catalysts, but also segregates incompatible processes. This division of labor facilitates metabolic ______________ and _________________.

Answer 5

solutes; flexibility and efficiency

Question 6

Membrane transport underlies many essential cell biological processes. Name 7 of them.

Answer 6

1. Nutrient acquisition.
2. Metabolite distribution.
3. Compartmentalization of metabolites.
4. Energy transduction.
5. Turgor generation.
6. Waste product excretion.
7. Signal transduction.

Question 7

Transport proteins can be regarded as ______________ enzymes.

Answer 7

conventional

Question 8

Pumps catalyze ______ transport, coupling the energy liberated from ________________ of _____ to transport of a specific molecule against an electrochemical gradient.

Answer 8

active; hydrolysis; ATP

Question 9

Channels and cotransporters facilitate _______ transport, utilizing energy stored in ______________________ _____________ to power transport.

Answer 9

passive; electrochemical gradients

Question 10

______________: form aqueous pores in the membrane to allow for passive transport.

Answer 10

channels

Question 11

___________________: transport specific molecules against an electrochemical gradient for passive transport.

Answer 11

cotransporters (carriers)

Question 12

In passive transport, the net change in free energy for all molecules transported is _______________.

Answer 12

negative

Question 13

Identify pumps, channels and cotransporters

Answer 13

!!

Question 14

What is the name for cotransporters that catalyze solute flux in the same direction as H+ or Na+ flux?

Answer 14

symporters

Question 15

___ ________ and ___ ______________ are the key players in determining the membrane potential of a cell.

Answer 15

H+ pumps; K+ channels

Question 16

A membrane potential or voltage results from gradients of _________ and _________ across the membrane.

Answer 16

cations and anions

Question 17

Living cells generally have a _______________ membrane potential.

Answer 17

negative

Question 18

Living cells generally have a negative membrane potential, because electrical potential favors release of __________ charged solutes and uptake of ___________ charged solutes.

Answer 18

negatively; positively

Question 19

__________ ____________ at the inner mitochondrial and thylakoid membranes are H+-pumps that synthesize ATP.

Answer 19

F-type ATPases
(f=factory so synthesize ATP)

Question 20

____________ _____________ covalently bind the γ-phosphate of ATP during catalysis.

Answer 20

P-type ATPases

Question 21

F-type ATPases harness pmf to drive ATP ___________.

F= factory

Answer 21

synthesis

Question 22

P-type PM H+-ATPase generates pmf by ___________ ATP.

Answer 22

hydrolyzes

Question 23

Most enzymes, PM H+-ATPase, that play pivotal roles in metabolism are subject to intense regulation. The pump is activated in response to lowered _______________ ___.

Answer 23

cytosolic pH

Question 24

DEFINITION: a toxin produced by a fungal pathogenic plant, Fusicoccum amygdali, that stimulates the P-type H+ ATPase.

Answer 24

fusicoccin

Question 25

PM H+-ATPase is activated by the ____________ and binding of 14-3-3 proteins.

Answer 25

phosphorylation

Question 26

________-_________ pumps are major players in the sequestration of AMPHIPATHIC METABOLITES and xenobiotics into the vacuole.

Answer 26

ABC-type pumps

Question 27

________: K+ influx channel; K+ uptake in roots

Answer 27

AKT1

Question 28

Arabidopsis akt1 mutants that are deficient in the AKT1 inward rectifying channel demonstrate ________________ growth in comparison to the wild type.

Answer 28

diminished

Question 29

DEFINITION: a superfamily of voltage-gated K+, Ca2+, and Na+ channels found in animal cells and named for the Drosophila mutant from which the first outward rectifying K+ channel was cloned.

Answer 29

Shaker family

Question 30

DEFINITION: a transmembrane protein that is involved in the opening of a channel in response to a permissive voltage.

Answer 30

voltage sensor

Question 31

The activity of voltage-dependent K+ channels at the plasma membrane is regulated by _______________ and _____________________.

Answer 31

voltage and phosphorylation

Question 32

Monovalent _____________ ____________ at the vacuolar membrane are [Ca2+]-sensitive and mediate vacuolar K+ mobilization.

Answer 32

cation channels

Question 33

Activities of vacuolar FV K+ channels depend on _______________ ____ and ____. | whether the channel is open or closed

Answer 33

cytosolic pH and Ca2+.

Question 34

High-affinity ___ ______________ are present at the plasma membrane.

Answer 34

K+ transporters

Question 35

Besides the biophysically and physiologically well-studied functions of K+ channels, plants possess a large number of K + transporters that do NOT belong to typical ____ __________ families. ## Footnote transporters are different from channels

Answer 35

ion channel

Question 36

Ca2+ ions are taken up into the cytosol predominantly by ion channels, rather than __________-_____________ transporters.

Answer 36

proton-coupled