Ch 09: Cell Communication

Question 1

apoptosis

Answer 1

programmed cell death

Question 2

autocrine signal

Answer 2

**signal **that is sent and received by the same or similar nearby cells

Question 3

autoinducer

Answer 3

signaling molecule secreted by bacteria to communicate with other bacteria of its kind

Question 4

cell-surface receptor

Answer 4

cell-surface protein that transmits a signal from the exterior of the cell to the interior, even though the ligand does not enter the cell

Question 5

chemical synapse

Answer 5

small space between axon terminals and dendrites of nerve cells where neurotransmitters function

Question 6

cyclic AMP (cAMP)

Answer 6

second messenger that is derived from ATP

Question 7

cyclic AMP-dependent kinase
(also, protein kinase A, or PKA)

Answer 7

kinase that is activated by binding to cAMP

Question 8

diacylglycerol (DAG)

Answer 8

cleavage product of PIP2 that is used for signaling within the plasma membrane

Question 9

dimer

Answer 9

chemical compound formed when two molecules join together

Question 10

dimerization

Answer 10

(of receptor proteins) interaction of two receptor proteins to form a functional complex called a dimer

Question 11

endocrine cell

Answer 11

**cell ** that releases ligands involved in endocrine signaling (hormones)

Question 12

endocrine signal

Answer 12

long-distance signal that is delivered by ligands (hormones) traveling through an organism’s circulatory system from the signaling cell to the target cell

Question 13

enzyme-linked receptor

Answer 13

cell-surface receptor with intracellular domains that are associated with membrane-bound enzymes

Question 14

extracellular domain

Answer 14

region of a cell-surface receptor that is located on the cell surface

Question 15

G-protein-linked receptor

Answer 15

cell-surface receptor that activates membrane-bound G-proteins to transmit a signal from the receptor to nearby membrane components

Question 16

growth factor

Answer 16

ligand that binds to cell-surface receptors and stimulates cell growth

Question 17

inhibitor

Answer 17

molecule that binds to a protein (usually an enzyme) and keeps it from functioning

Question 18

inositol phospholipid

Answer 18

lipid present at small concentrations in the plasma membrane that is converted into a second messenger; it has inositol (a carbohydrate) as its hydrophilic head group

Question 19

inositol triphosphate (IP3)

Answer 19

cleavage product of PIP2 that is used for signaling within the cell

Question 20

intercellular signaling

Answer 20

communication between a cell

Question 21

internal receptor
(also, intracellular receptor)

Answer 21

receptor protein that is located in the cytosol of a cell and binds to ligands that pass through the plasma membrane

Question 22

intracellular mediator
(also, second messenger)

Answer 22

small molecule that transmits signals within a cell

Question 23

intracellular signaling

Answer 23

communication within cells

Question 24

ion channel-linked receptor

Answer 24

cell-surface receptor that forms a plasma membrane channel, which opens when a ligand binds to the extracellular domain (ligand-gated channels)

Question 25

kinase

Answer 25

enzyme that catalyzes the transfer of a phosphate group from ATP to another molecule

Question 26

ligand

Answer 26

molecule produced by a signaling cell that binds with a specific receptor, delivering a signal in the process

Question 27

mating factor

Answer 27

signaling molecule secreted by yeast cells to communicate to nearby yeast cells that they are available to mate

Question 28

neurotransmitter

Answer 28

chemical ligand that carries a signal from one nerve cell to the next

Question 29

paracrine signal

Answer 29

**signal **between nearby cells that is delivered by ligands traveling in the liquid medium in the space between the cells

Question 30

phosphatase

Answer 30

enzyme that removes the phosphate group from a molecule that has been previously phosphorylated

Question 31

phosphodiesterase

Answer 31

enzyme that degrades cAMP, producing AMP, to terminate signaling

Question 32

quorum sensing

Answer 32

method of cellular communication used by bacteria that informs them of the abundance of similar (or different) bacteria in the environment

Question 33

receptor

Answer 33

protein in or on a target cell that bind to ligands

Question 34

second messenger

Answer 34

small, non-protein molecule that propagates a signal within the cell after activation of a receptor causes its release

Question 35

signal integration

Answer 35

interaction of signals from two or more different cell-surface receptors that merge to activate the same response in the cell

Question 36

signal transduction

Answer 36

propagation of the signal through the cytoplasm (and sometimes also the nucleus) of the cell

Question 37

signaling cell

Answer 37

**cell **that releases signal molecules that allow communication with another cell

Question 38

signaling pathway
(also signaling cascade)

Answer 38

chain of events that occurs in the cytoplasm of the cell to propagate the signal from the plasma membrane to produce a response

Question 39

synaptic signal

Answer 39

chemical signal (neurotransmitter) that travels between nerve cells

Question 40

target cell

Answer 40

**cell **that has a receptor for a signal or ligand from a signaling cell