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Cell Bio > Chapter 12 > Flashcards

Chapter 12 Flashcards

1
Q

Lipid bilayers are impermeable to

A

Solutes and ions

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2
Q

Membrane transport proteins fall into two classes:

A

transporters and channels

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3
Q

Solutes cross membrane by either

A

Passive or active transport

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4
Q

What concentrations are high outside the cell

A

Na, Cl, Mg, Ca

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5
Q

What concentration is high inside the cell

A

K

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6
Q

The rate at which a molecule crosses a lipid bilayer depends on its

A

Size and solubility

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7
Q

Membranes are permeable to

A

Small, hydrophobic and uncharged molecules

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8
Q

Membranes less permeable to

A

Large, polar molecules and ions

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9
Q

change shape to move solutes

A

Transporters

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10
Q

Can be passive or active

A

Transporters

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11
Q

Function as pores

A

Ion channel

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12
Q

Ion channels are always

A

Passive

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13
Q

What gradient drives transport

A

Electrochemical

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14
Q

Movement of charged molecules depends on

A

Both the concentration and electrical gradient

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15
Q

Transitions between conformations are

A

Random, reversible, and don’t depend on solute binding

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16
Q

move solutes across the membrane
along their electrochemical gradients (no ATP required)

A

Passive transporters

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17
Q

actively transport solutes against their
electrochemical gradients (requires an input of energy, like ATP)

A

Pumps

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18
Q

use a gradient of one solute across a
membrane to drive the active transport of a second molecule

A

Coupled pumps

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19
Q

Glucose transporter mediates

A

Passive transport

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20
Q

Because __ is uncharged, the electrical component of its electrochemical gradient is zero.

A

glucose

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21
Q

transport moves solutes against their electrochemical
gradients (e.g., moving Na + out of the cell)

A

Active

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22
Q

Animal cells use __ to pump Na + out and K+ in

A

ATP Hydrolysis

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23
Q

The __ is driven by a cycle of phosphorylation and dephosphorylation

A

Na+-K+ pump

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24
Q

helps maintain the osmotic balance of animal cells

A

Na+-K+ pump

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25
Q

Intracellular Ca2+ concentrations are kept

A

Low by Ca pumps (driven by atp hydrolysis)

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26
Q

The Glucose-Na+ symport is a

A

Coupled pump

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27
Q

uses energy from transporting Na+ along its electrochemical gradient to transport glucose against its gradient

A

Glucose Na symport

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28
Q

drive membrane transport in plants, fungi, and
bacteria

A

Proton (H+) pumps

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29
Q

Na K pump, pumps what in and out

A

3 Na out and 2 K ions against gradients

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30
Q

__ drives conformational changes

A

Phosphorylation

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31
Q

Ca2+ ATPase/pump reduces

A

cytosolic calcium

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32
Q

Ca2+ ATPase/pump located in the

A

ER membrane and membrane

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33
Q

Cytosolic levels must be kept

A

Low

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34
Q

Calcium concentration important for

A

Cell signaling

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35
Q

A gradient of any solute across a membrane can be used to drive the active transport of a second molecule

A

Coupled pumps

36
Q

use ion gradients to drive the active transport
of two solutes in the same or opposite direction

A

Symport & antiport

37
Q

passive transport of one solute

A

Uniport

38
Q

Coupled transporters use __ to take up nutrients actively

A

ion gradients

39
Q

Glucose-Na+
symport in apical
membrane

A

Active

40
Q

Glucose uniport in
basal membrane

A

Passive

41
Q

Na+-K+ pump
maintains ion
gradients by
hydrolyzing ATP

A

Active

42
Q

What determines the direction of passive transport across
the membrane?

A

The electrochemical gradient of the solute

43
Q

Pumps actively transport solutes __ their electrochemical gradients

A

against

44
Q

couples the transport of one solute against
its electrochemical gradient with the transport of another solute along its electrochemical gradient

A

Gradient driven/coupled

45
Q

Three types of active transport

A

Gradient driven, atp driven, or light driven

46
Q

uses energy from ATP hydrolysis

A

ATP driven

47
Q

2 types of gradient-driven pumps, based on the direction of coupled transport:

A

Symport and aniport

48
Q

Glucose transporter is __ and an example of a __

A

Passive, uniport

49
Q

Active transporters atp driven

A

Na/K, Ca ATPase and H pump

50
Q

Ca2+ ATPase moves what

A

2 ions out of cell or into the ER

51
Q

Active transporters gradient driven

A

Glucose Na symport

52
Q

The movement of an ion down its electrochemical gradient is
a form of active transport.
T or F

A

False, passive

53
Q

Coupled transporters use electrochemical gradients to drive active transport of other solutes.
T or F

A

True

54
Q

The transport of glucose across the membrane can be active
or passive, depending on the nature of the transporter. T or F

A

True, active is glucose sodium symport and passive is glucose transporter

55
Q

Ion channels are

A

selective and gated

56
Q

Ion channels randomly…

A

snap between open and closed

57
Q

VG ion channels respond to the

A

membrane potential

58
Q

Small pores that filter ions by size and charged

A

ion channel

59
Q

The frequency of opening and closing of an ion channel depends on the

A

presence of a specific stimulus

60
Q

what channel responds to neurotransmitters binding

A

ligand gated

61
Q

what channel responds to mechanical stimulus

A

mechanically or stress gated channel

62
Q

What accounts for RMP

A

K leak channels

63
Q

if a membrane is permeable to an ion, then the membrane
potential is

A

determined by the Nernst equation

64
Q

The nerst equation is dependant on the

A

ratio of ion concentration outside vs. inside

65
Q

In a resting cell, the Nernst equation is determined by

A

K

66
Q

In the ear, sound vibrations on auditory hair cells opens what channel

A

stress gated ion channels, leading to AP

67
Q

Tilting the stereocilia in the ear in response to sound vibrations has what effect

A

pulls on linking filament, opening ion channel

68
Q

Action potentials are usually mediated by

A

voltage-gated Na+
channels

69
Q

Voltage-gated Ca2+ channels convert

A

electrical signals into
chemical signals at nerve terminals

70
Q

Ligand-gated channels in target cells convert

A

chemical signals back
into electrical signals

71
Q

Neurons receive what kind of inputs

A

excitatory and inhibitory

72
Q

major targets for psychoactive drugs

A

Ligand-gated ion channels (transmitter)

73
Q

Action potentials are converted into __ signals
via the release of neurotransmitters at the nerve terminal

A

electrical converted into chemical

74
Q

When a neuron is stimulated, the membrane potential of the plasma membrane shifts to a

A

less negative value

75
Q

After opening, Na+ channels rapidly become

A

inactivated

76
Q

The Na+ channels remain in the inactivated state until the

A

membrane potential
has returned to its resting, negative value

77
Q

Action potential only moves in

A

1 direction

78
Q

prevents the action potential from moving backwards

A

Na+ channel inactivation

79
Q

channels at nerve terminals
of pre-synaptic cell

A

Voltage-gated Ca2+

80
Q

Convert electrical signal (ions from the action potential) to a chemical signal
(neurotransmitter)

A

voltage gated calcium channels

81
Q

The acetylcholine (Ach) receptor is a

A

transmitter-gated ion channel

82
Q

After Ach binds to a channel what happens

A

influx of sodium, causing AP

83
Q

Influx of __ tends to keep the membrane polarized, decreasing firing of an action potential

A

Cl, inhibitory synapse

84
Q

Excitatory synapse has what ion

A

sodium

85
Q

Acetylcholine and glutamate are __ neurotransmitters, bind __ channels

A

excitatory, ligand-gated
cation

86
Q

GABA and glycine are __, bind __ channels

A

inhibitory, ligand-gated Cl-

Cell Bio (15 decks)

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