Ch 16 - Cell Signaling

Question 1

adaptation

Answer 1

adjustment of sensitivity following repeated stimulation; allows a cell or organism to register small changes in a signal despite a high background level of stimulation

Question 2

adenylyl cyclase

Answer 2

enzyme that catalyzes the formation of cyclic AMP from ATP; an important component in some intracellular signaling pathways

Question 3

Ca2+/calmodulin-dependent protein kinase (CaM-kinase)

Answer 3

enzyme that phosphorylates target proteins in response to an increase in Ca2+ ion concentration through its interaction with the Ca2+ binding protein calmodulin

Question 4

calmodulin

Answer 4

small Ca2+-binding protein that modifies the activity of many target proteins in response to changes in Ca2+ concentration

Question 5

cell signaling

Answer 5

the molecular mechanisms by which cells detect and respond to external stimuli and send messages to other cells

Question 6

cyclic AMP

Answer 6

small intracellular signaling molecule generated from ATP in response to hormonal stimulation of cell-surface receptors

Question 7

cyclic-AMP-dependent-protein-kinase (PKA)

Answer 7

enzyme that phosphorylates target proteins in response to a rise in intracellular cyclic AMP concentration

Question 8

diacylglycerol (DAG)

Answer 8

small messenger molecule produced by the cleavage of membrane inositol phospholipids in response to extracellular signals. helps activate protein kinase C

Question 9

enzyme-coupled-receptor

Answer 9

transmembrane protein that, when stimulated by the binding of a ligand, activates an intracellular enzyme (either a separate enzyme or part of the receptor itself)

Question 10

extracellular signal molecule

Answer 10

any molecule present outside the cell that can elicit a response inside the cell when the molecule binds to a receptor

Question 11

G protein

Answer 11

a membrane-bound GTP-binding protein involved in intracellular signaling; composed of three subunits, this intermediary is usually activated by the binding of a hormone or other ligand to a transmembrane receptor

Question 12

G-protein-coupled receptor (GPCR)

Answer 12

Cell-surface receptor that associates with an intracellular trimeric GTP-binding protein (G protein) after activation by an extracellular ligand. these receptors are embedded in the membrane by seven transmembrane α helices

Question 13

GTP-binding protein

Answer 13

intracellular signaling protein whose activity is determined by its association with either GTP or GDP. includes both trimeric G proteins and monomeric GTPases, such as Ras

Question 14

hormone

Answer 14

extracellular signaling molecule that is secreted and transported via the bloodstream (in animals) or the sap (in plants) to target issues on which it exerts a specific effect

Question 15

inositol 1,4,5-triphosphate (IP3)

Answer 15

small intracellular signaling molecule that triggers the release of Ca2+ from the endoplasmic reticulum into the cytosol; produced when a signal molecule activates a membrane-bound protein called phospholipase C.

Question 16

inositol phospholipid

Answer 16

minor lipid component of plasma membrane proteins that plays a part in signal transduction in eukaryotic cells; cleavage yields two smaller messenger molecules: IP3 and diacylglycerol

Question 17

intracellular signaling pathway

Answer 17

a set of proteins and small-molecule second messengers that interact with each other to relay a signal from the cell membrane to its final destination in the cytoplasm or nucleus

Question 18

ion-channel-coupled receptor

Answer 18

transmembrane receptor protein or protein complex that opens in response to the binding of a ligand to its external face, allowing the passage of a specific ion

Question 19

local mediator

Answer 19

secreted signal molecule that acts at a short range of adjacent cells

Question 20

MAP kinase

Answer 20

mitogen activated protein kinase. signaling molecule that is the final kinase in a three-kinase sequence called the MAP-kinase signaling module

Question 21

MAP-kinase signaling module

Answer 21

set of three functionally interlinked protein kinases that allows cells to respond to extracellular signal molecules taht stimulate proliferation; includes a mitogen-activated protein kinase (MAP kinase), a MAP kinase kinase and a MAP kinase kinase kinase

Question 22

molecular switch

Answer 22

intracellular signaling protein that toggles between an active and inactive state in response to receiving a signal

Question 23

monomeric GTPase

Answer 23

small, single-subunit GTP-binding protein. proteins of this family, such as Ras and Rho, are part of many different signaling pathways

Question 24

neurotransmitter

Answer 24

small signaling molecule secreted by a nerve cell at a synapse to transmit information to a postsynaptic cell. examples include acetylcholine, glutamate, GABA, glycine

Question 25

nitric oxide (NO)

Answer 25

locally acting gaseous signal molecule that diffuses across cell membranes to affect the activity of intracellular proteins

Question 26

nuclear receptor

Answer 26

protein inside of eukaryotic cell that, on binding to a signal molecule, enters the nucleus and regulates transcription

Question 27

phosphoinositide 3-kinase (PI 3-kinase)

Answer 27

enzyme that phosphorylates inositol phospholipids in the plasma membrane, which generates docking sites for intracellular signaling proteins that promote cell growth and survival

Question 28

phospholipase C

Answer 28

enzyme associated with the plasma membrane that generates two small messenger molecules in response to activation

Question 29

protein kinase

Answer 29

enzyme that catalyzes the transfer of a phosphate group from ATP to a specific amino acid side chain on a target protein

Question 30

protein kinase C (PKC)

Answer 30

enzyme that phosphorylates target proteins in response to a rise in diacylglycerol and Ca2+ ions

Question 31

protein phosphatase

Answer 31

enzyme that catalyzes the removal of a phosphate group from a protein, often with high specificity for the phosphorylation site

Question 32

Ras

Answer 32

one of a large family of small GTP-binding proteins (the monomeric GTPases) that helps relay signals from cell-surface receptors to the nucleus. many human cancers contain an overactive mutant form of the protein

Question 33

receptor

Answer 33

protein that recognizes and responds to a specific signal molecule

Question 34

receptor serine/threonine kinase

Answer 34

enzyme-coupled receptor that phosphorylates target proteins on serine or threonine

Question 35

receptor tyrosine kinase (RTK)

Answer 35

enzyme-coupled receptor in which the intracellular domain has a tyrosine kinase activity, which is activated by ligand binding to the receptor's extracellular domain

Question 36

serine/threonine kinase

Answer 36

enzyme that phosphorylates target proteins on serines or threonines

Question 37

signal transduction

Answer 37

conversion of an impulse or stimulus from one physical or chemical form to another. in cell biology, the process by which a cell responds to an extracellular signal

Question 38

steroid hormone

Answer 38

hydrophobic signal molecule related to cholesterol; can pass through the plasma membrane to interact with intracellular receptors that affect gene expression in the target cell. examples include oestrogen and testosterone

Question 39

tyrosine kinase

Answer 39

enzyme that phosphorylates target proteins on tyrosines