Chapter 5 - Chemical Messengers

Question 1

the process by which the binding of a chemical messenger to receptors brings about a response in a target cell

Answer 1

signal transduction

Question 2

protein on a target cell that recognizes and binds a chemical messenger

Answer 2

receptor

Question 3

type of chemical messenger that communicates with neighboring cells by simple diffusion

Answer 3

paracrine

Question 4

proteins that stimulate proliferation and differentiation of cells

Answer 4

growth factors

Question 5

proteins that stimulate formation of a blood clot

Answer 5

clotting factors

Question 6

peptides that coordinate the body’s defense against infections

Answer 6

cytokines

Question 7

What are the three main functional classes of chemical messengers?

Answer 7

1. paracrines
2. neurotransmitters
3. hormones

Question 8

What are the five major chemical classes of messengers?

Answer 8

1. amino acids
2. amines
3. peptides/proteins
4. steroids
5. eicosanoids

Question 9

What determines whether a polypeptide is classified as a protein or a peptide?

Answer 9

Peptides are chains containing fewer than 50 amino acids.

Question 10

Which messengers are lipophobic?

Answer 10

1. amino acids
2. amines
3. peptides/proteins

Question 11

Which messengers are liphphilic?

Answer 11

1. steroids

2. eicosanoids

Question 12

lipophilic

Answer 12

lipid soluble, crosses the plasma membrane

Question 13

lipophobic

Answer 13

water soluble, cannot cross the plasma membrane

Question 14

samples of paracrines

Answer 14

growth factors, clotting factors, cytokines

Question 15

communication by neurotransmitters

Answer 15

synaptic signaling

Question 16

Direct communication between cells in contact with one another is accomplished through _____.

Answer 16

gap junctions

Question 17

The number of bound receptors on a target cell depends on what two things?

Answer 17

1. the concentration of the messenger

2. the concentration of receptors on the target cell

Question 18

Which type of chemical messenger, when released, binds to receptors on the cell that released the chemical messenger?

Answer 18

autocrine

Question 19

Which type of chemical messenger is released into the bloodstream by an endocrine gland where it can affect target cells throughout the body?

Answer 19

hormone

Question 20

Vasopressin is an example of which type of chemical messenger?

Answer 20

neurohormone

Question 21

Histamine acts as a(n) _____ in its role in inflammation.

Answer 21

paracrine

Question 22

Which class of messengers are derived from cholesterol?

Answer 22

steroids

Question 23

Arachidonic acid is the raw material for the synthesis of _____.

Answer 23

eicosanoids

Question 24

Most chemical messengers fall into which chemical class?

Answer 24

peptides/proteins

Question 25

All amino acid chemical messengers function as _____.

Answer 25

neurotransmitters

Question 26

All steroid chemical messengers function as _____.

Answer 26

hormones

Question 27

Which amines are lipophilic?

Answer 27

thyroid hormones

Question 28

Where are the receptors located on all eicosanoids and most steroids?

Answer 28

cytosol

Question 29

the strength of the binding between a messenger and its receptor

Answer 29

affinity

Question 30

ligands that produce a response

Answer 30

agonists

Question 31

ligands that do not produce a response

Answer 31

antagonists

Question 32

Receptors for which messengers are located on the plasma membrane?

Answer 32

lipophobic

Question 33

What are the three types of lipophobic receptors?

Answer 33

1. channel-linked 2. enzyme-linked 3. G protein-linked

Question 34

In the cAMP second messenger system, the G protein releases the alpha subunit, which binds to and activates the enzyme _____.

Answer 34

adenylate cyclase

Question 35

Adenylate cyclase catalyzes the conversion of _____ to _____.

Answer 35

ATP; cAMP

Question 36

cAMP

Answer 36

cyclic AMP

Question 37

cAMP activates _____.

Answer 37

protein kinase A (also called cAMP-dependent protein kinase)

Question 38

In the phosphatidylinositol second messenger system, the G protein releases the alpha subunit, which binds to and activates the enzyme _____.

Answer 38

phospholipase C

Question 39

Phospholipase C catalyzes the conversion of _____ to _____ and ___, each of which functions as a second messenger.

Answer 39

PIP2; DAG; IP3

Question 40

_____ remains in the membrane and activates the enzyme protein kinase C.

Answer 40

DAG

Question 41

_____ moves into the cytosol and triggers the release of calcium from the endoplasmic reticulum.

Answer 41

IP3

Question 42

_____ catalyzes the phosphorylation of a protein.

Answer 42

Protein kinase C

Question 43

Hormones travel through the bloodstream dissolved in plasma or attached to _____.

Answer 43

carrier proteins