Kapitel 12

Question 1

Traveling wave of electrical excitation caused by rapid - transient - self-propagating depolarization of the plasma membrane in a neuron or other excitable cell; also called a nerve impulse.

Answer 1

action potential

Question 2

The movement of a solute across a membrane against its electrochemical gradient; requires an input of energy - such as that provided by ATP hydrolysis.

Answer 2

active transport

Question 3

Long - thin extension that conducts electrical signals away from a nerve cell body toward remote target cells.

Answer 3

axon

Question 4

An active transporter that uses energy supplied by ATP hydrolysis to actively expel Ca2+ from the cell cytosol.

Answer 4

Ca2+ pump

Question 5

A protein that forms a hydrophilic pore across a membrane - through which selected small molecules or ions can passively diffuse.

Answer 5

channel

Question 6

Active transporter that uses the movement of one solute down its electrochemical gradient to drive the uphill transport of another solute across the same membrane.

Answer 6

coupled pump

Question 7

Short - branching structure that extends from the surface of a nerve cell and receives signals from other neurons.

Answer 7

dendrite

Question 8

A shift in the membrane potential - making it less negative.

Answer 8

depolarization

Question 9

Driving force that determines which way an ion will move across a membrane; consists of the combined influence of the ion’s concentration gradient and the membrane potential.

Answer 9

electrochemical gradient

Question 10

Transmembrane protein that forms a pore across the lipid bilayer through which specific inorganic ions can diffuse down their electrochemical gradients.

Answer 10

ion channel

Question 11

Ion channel permeable to K + that randomly flickers between an open and closed state; largely responsible for the resting membrane potential in animal cells.

Answer 11

K + leak channel

Question 12

An ion channel that is stimulated to open by the binding of a small molecule such as a neurotransmitter.

Answer 12

ligand-gated channel

Question 13

An ion channel that allows the passage of select ions across a membrane in response to a physical perturbation.

Answer 13

mechanically gated channel

Question 14

Voltage difference across a membrane due to a slight excess of positive ions on one side and of negative ions on the other.

Answer 14

membrane potential

Question 15

Any transmembrane protein that provides a passageway for the movement of select substances across a cell membrane.

Answer 15

membrane transport protein

Question 16

Transporter found in the plasma membrane of most animal cells that actively pumps Na+ out of the cell and K+ in using the energy derived from ATP hydrolysis.

Answer 16

Na+ pump (sodium pump)

Question 17

An equation that relates the concentrations of an inorganic ion on the two sides of a permeable membrane to the membrane potential at which there would be no net movement of the ion across the membrane.

Answer 17

Nernst equation

Question 18

Structure at the end of an axon that signals to another neuron or target cell.

Answer 18

nerve terminal

Question 19

An electrically excitable cell that integrates and transmits information as part of the nervous system; a nerve cell.

Answer 19

neuron

Question 20

Small signaling molecule secreted by a nerve cell at a synapse to transmit information to a postsynaptic cell. Examples include acetylcholine - glutamate - GABA - and glycine.

Answer 20

neurotransmitter

Question 21

Technique that uses light to control the activity of neurons into which light-gated ion channels have been artificially introduced.

Answer 21

optogenetics

Question 22

Passive movement of water across a cell membrane from a region where the concentration of water is high (because the concentration of solutes is low) to a region where the concentration of water is low (and the concentration of solutes is high).

Answer 22

osmosis

Question 23

The spontaneous movement of a solute down its concentration gradient across a cell membrane via a membrane transport protein - such as a channel or a transporter.

Answer 23

passive transport

Question 24

Technique used to monitor the activity of ion channels in a membrane; involves the formation of a tight seal between the tip of a glass electrode and a small region of cell membrane - and manipulation of the membrane potential by varying the concentrations of ions in the electrode.

Answer 24

patch-clamp recording

Question 25

A transporter that actively moves H+ across a cell membrane - thereby generating a gradient that can be used by the cell - for example - to import other solutes.

Answer 25

proton (H+) pump

Question 26

Transporter that uses a source of energy - such as ATP hydrolysis or sunlight - to actively move a solute across a membrane against its electrochemical gradient.

Answer 26

pump

Question 27

Voltage difference across the plasma membrane when a cell is not stimulated.

Answer 27

resting membrane potential

Question 28

A transporter that transfers two different solutes across a cell membrane in the same direction.

Answer 28

symport

Question 29

Specialized junction where a nerve cell communicates with another cell (such as a nerve cell - muscle cell - or gland cell) - usually via a neurotransmitter secreted by the nerve cell.

Answer 29

synapse

Question 30

The ability of a synapse to adjust its strength for a prolonged period - either up or down - depending on its use; thought to play an important role in learning and memory.

Answer 30

synaptic plasticity

Question 31

Small membrane-enclosed sac filled with neurotransmitter that releases its contents by exocytosis at a synapse.

Answer 31

synaptic vesicle

Question 32

Transmembrane receptor protein or protein complex that opens in response to the binding of a neurotransmitter - allowing the passage of a specific inorganic ion; its activation can trigger an action potential in a postsynaptic cell.

Answer 32

transmitter-gated ion channel

Question 33

Membrane transport protein that moves a solute across a cell membrane by undergoing a series of conformational changes.

Answer 33

transporter

Question 34

Force exerted on a plant cell wall when water enters the cell by osmosis; keeps plant from wilting.

Answer 34

turgor pressure

Question 35

Protein that selectively allows particular ions to cross a membrane in response to a change in membrane potential. Found mainly in electrically excitable cells such as nerve and muscle cells.

Answer 35

voltage-gated ion channel

Question 36

Protein in the plasma membrane of electrically excitable cells that opens in response to membrane depolarization - allowing Na+ to enter the cell. It is responsible for action potentials in these cells.

Answer 36

voltage-gated Na+ channel

Question 37

Type of coupled transporter that transfers two different ions or small molecules across a membrane in opposite directions - either simultaneously or in sequence.

Answer 37

antiport

Question 38

See Na+ pump

Answer 38

sodium pump

Question 39

Channel protein that permits the passage of selected ions - such as Na+ - across a membrane in response to changes in the membrane potential. Found primarily in electrically excitable cells such as nerve and muscle.

Answer 39

voltage-gated channel