Chapter 6 Cell communication

Question 1

cell signaling

Answer 1

Mechanisms of communication between cells. Cells
signal one another with secreted signaling molecules, or a signaling molecule on one cell combines with a receptor on another cell.

Question 2

reception

Answer 2

Process of detecting a stimulus.

Question 3

target cells

Answer 3

A cell or tissue with receptors that bind a

hormone.

Question 4

signal transduction

Answer 4

process in which a cell converts and amplifies an extracellular signal into an intracellular signal that affects some function in the cell.

Question 5

response

Answer 5

any behavior of a living organism that results from an external or internal stimulus.

Question 6

neurotransmitters

Answer 6

A chemical signal used by neurons to transmit

impulses across a synapse

Question 7

Hormones

Answer 7

A chemical messenger, oft en produced in one region of the body of a multicellular organism and transported to another region where it signals cells to alter some aspect of growth, development, or metabolism.

Question 8

endocrine glands

Answer 8

A gland that secretes hormones directly

into the blood or tissue fluid instead of into ducts.

Question 9

Local regulators

Answer 9

Prostaglandins (a group of local hormones), growth
factors, cytokines, and other soluble molecules that act on nearby cells by paracrine regulation or act on the cells that produce them (autocrine regulation).

Question 10

paracrine regulation

Answer 10

A type of regulation in which a signal molecule (e.g., certain hormones) diffuses through interstitial fluid and acts on nearby target cells.

Question 11

prostaglandins

Answer 11

A group of local regulators derived from fatty acids; synthesized by most cells of the body and produce a wide variety of effects; sometimes called local hormones.

Question 12

nitric oxide

Answer 12

A gaseous signaling molecule; a neurotransmitter.

Question 13

ion channel–linked receptor

Answer 13

are cell membrane bound receptors. They act through synaptic signaling on electrically excitable cells and convert chemical signals (ligand) to electrical ones.[1] It is essential in neuronal activities.

Question 14

G protein–linked receptors

Answer 14

a large protein family of receptors that sense molecules outside the cell and activate inside signal transduction pathways and, ultimately, cellular responses. are found only in eukaryotes, including yeast, choanoflagellates,[3] and animals.

Question 15

G protein

Answer 15

One of a group of proteins that bind GTP and are involved

in the transfer of signals across the plasma membrane.

Question 16

Enzyme-linked receptors

Answer 16

also known as a catalytic receptor, is a transmembrane receptor, where the binding of an extracellular ligand causes enzymatic activity on the intracellular side.[

Question 17

Intracellular receptors

Answer 17

Receptors located inside the cell rather than on its cell membrane. Classic hormones that use intracellular receptors include thyroid and steroid hormones.

Question 18

protein kinase cascade

Answer 18

A signaling pathway in which a series of protein kinase molecules are phosphorylated

Question 19

guanosine

diphosphate (GDP)

Answer 19

consists of the pyrophosphate group, the pentose sugar ribose, and the nucleobase guanine.

Question 20

guanosine triphosphate

GTP

Answer 20

An energy transfer molecule similar to ATP that releases free energy with the hydrolysis of its terminal phosphate group.

Question 21

transcription factors

Answer 21

a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the rate of transcription of genetic information from DNA to messenger RNA.

Question 22

first messenger

Answer 22

extracellular factor that elicits a response within a cell. As such, first messengers are incredibly diverse, ranging from environmental factors, such as light or heat, to small molecules and peptides, up through large multivalent proteins.

Question 23

second

messenger

Answer 23

are intracellular signaling molecules released by the cell to trigger physiological changes such as proliferation, differentiation, migration, survival, and apoptosis. Examples of second messenger molecules include Cyclic AMP, Cyclic GMP, Inositol Triphosphate, Diacylglycerol, and Calcium.

Question 24

adenylyl cyclase

Answer 24

Is an enzyme with key regulatory roles in essentially all cells. Adenylyl cyclase catalyze the conversion of adenosine triphosphate (ATP) and pyrophosphate.

Question 25

cyclic AMP (cAMP)

Answer 25

A form of adenosine monophosphate in which the phosphate is part of a ring-shaped structure; acts as a regulatory molecule and second messenger in organisms ranging from bacteria to humans.

Question 26

protein kinase

Answer 26

One of a group of enzymes that activate or inactivate

other proteins by phosphorylating (adding phosphate groups to) them.

Question 27

inositol trisphosphate (IP3)

Answer 27

A second messenger that increases intracellular calcium concentration and activates enzymes.

Question 28

diacylglycerol (DAG)

Answer 28

A lipid consisting of glycerol combined chemically with two fatty acids; also called diglyceride. Compare with monoacylglycerol and triacylglycerol.

Question 29

calmodulin

Answer 29

A calcium-binding protein; when bound, it alters the

activity of certain enzymes or transport proteins.

Question 30

Signal amplification

Answer 30

The process by which a few signaling molecules can effect major responses in the cell; the strength of each signaling
molecule is magnified.

Question 31

Signal termination

Answer 31

a specific sequence in DNA at which the RNA polymerase and the newly made RNA transcript are released from their DNA association.

Question 32

biofilm

Answer 32

community of microorganisms attached to a solid surface

Question 33

Receptors

Answer 33

large proteins or glycoproteins that bind with signaling molecules. Many types of signaling molecules do not actually enter the target cell.

Question 34

interstitial fluid

Answer 34

the fluid surrounding the cells, and acts on nearby cells.

Question 35

Histamine

Answer 35

is a local regulator that is stored in certain cells of the

immune system and is released in response to allergic reactions, injury, or infection

Question 36

Ligand

Answer 36

a molecule, other than an enzyme, that binds specifically to a macromolecule (usually a protein), forming a macromolecule-ligand complex Most ligands are hydrophilic molecules that bind to protein receptors on the surface of target cells

Question 37

rhodopsin

Answer 37

is part of a signal transduction pathway that leads to vision in dim light.

Question 38

phytochromes

Answer 38

family of blue-green pigment proteins that are activated by red light. Activation can lead to changes, such as flowering

Question 39

cryptochromes

Answer 39

pigments that absorb blue light. Cryptochromes play a role in biological rhythms.

Question 40

receptor down-regulation.

Answer 40

the concentration of the hormone insulin is too high for an extended period, cells decrease the number of their insulin receptors.

Question 41

Receptor up-regulation

Answer 41

occurs in response to low hormone concentrations amplifies the signaling molecule’s effect on the cell.

Question 42

acetylcholine

Answer 42

a neurotransmitter that binds to an acetylcholine receptor. This receptor is a ligand-gated sodium ion channel that is important in muscle contraction.

Question 43

kinase

Answer 43

enzyme that transfers the terminal phosphate group from ATP to a substrate This process is called phosphorylation

Question 44

tyrosine kinase

Answer 44

an enzyme that catalyzes the transfer of phosphate groups from ATP to a specific tyrosine that is part of a protein. (Tyrosine is an amino acid.)

Question 45

Brassinosteroids (BRs)

Answer 45

group of plant steroid hormones, regulate many plant processes, including cell division, cell elongation, and flower development

Question 46

ethylene

Answer 46

plant hormone that regulates a variety of processes, including seed germination and ripening of fruit. Ethylene is also important in plant responses to stressors.

Question 47

phosphatase

Answer 47

enzyme that catalyzes the removal of a phosphate group by hydrolysis; the process is called dephosphorylation. Protein phosphatases help regulate protein kinase cascades

Question 48

Gamma-aminobutyric acid (GABA)

Answer 48

neurotransmitter that binds to GABA receptors. One class of GABA receptors consists of ligand-gated chloride ion channels.

Question 49

phosphodiesterase

Answer 49

an enzyme that converts cAMP to adenosine monophosphate (AMP)