Chapter 9

Question 1

An example of a ligand for a cytoplasmic receptor is

Answer 1

a steroid

Question 2

Which type of receptor undergoes a conformational change upon activation

Answer 2

all of them do

Question 3

What is an example of a GPCRs and the role of a second messenger

Answer 3

adrenaline

Question 4

What is an example of receptor kinases

Answer 4

growth factors

Question 5

What is an example of ligand-gated ion channels

Answer 5

nervous system

Question 6

What are the four steps in cell signaling

Answer 6

receptor activation, signal transduction, response, termination

Question 7

When a signal binds to a receptor what happens to the receptor

Answer 7

it changes shape, this reaction is reversible/transient

Question 8

What is an endocrine signal

Answer 8

hormone signal to distant cells usually via circulatory system

Question 9

What is a paracrine signal

Answer 9

affects nearby cells

Question 10

What is an autocrine signal

Answer 10

affect the cells that made them

Question 11

What is a contact-development signal

Answer 11

touch to activate

Question 12

Membrane receptors: location, bind what, example

Answer 12

in the plasma membrane, bind polar ligands, insulin

Question 13

Intracellular receptors: location, bind what, example

Answer 13

in the cytoplasm, bind nonpolar ligands that diffuse across the PM, estrogen (lipids)

Question 14

What is another name for an intracellular receptor

Answer 14

cytoplasmic receptor

Question 15

Caffeine _______ brain activity and _______ adenosine, which _______ brain activities

Answer 15

increases, blocks, slows down

Question 16

Caffeine binds ______ activating the receptor

Answer 16

without

Question 17

Active cells signal ______ the cell causing a ____ response

Answer 17

inside, new

Question 18

What does heterotrimeric mean? What does monomeric mean?

Answer 18

3 different subunits
one subunit

Question 19

How are heterotrimeric G proteins, such as Gα, and
the monomeric G proteins such as Ras different

Answer 19

They are structurally different and are activated by different
signaling pathways

Question 20

G proteins are active when they are bound to

Answer 20

GTP

Question 21

Is the term “G-protein” just a shorter name for a G-protein coupled receptor?

Answer 21

No

Question 22

You strip off any proteins on the cell surface by using a protease. Now when you add a specific signaling molecule, the cell still responds. Why?

Answer 22

the receptor is in the interior of the cell

Question 23

What component of the pathway is not a protein kinase

Answer 23

Ras

Question 24

What is a components of the pathway of GTPase

Answer 24

Ras

Question 25

In a flight or fight response which molecules are activated by a shape change when adrenaline is present?

Answer 25

receptor, protein kinase A

Question 26

Would you expect phosphorylation of glycogen synthase to activate or inactive the enzyme?

Answer 26

Inactivate

Question 27

A mutation that inactivates the ability of the receptor to interact with the G protein would?

Answer 27

inhibit the fight-or-flight response

Question 28

Suppose a mutation occurred that resulted in the G protein losing its ability to hydrolyze GTP to GDP. How would this mutation affect the fight-or-flight response?

Answer 28

It would over-activate the fight-or-flight response

Question 29

In the fight-or-flight signaling pathway, suppose there is a mutation that results in the permanent activation of PKA. How would this mutation affect the response?

Answer 29

It would over-activate it

Question 30

Supposed you are a research scientist studying the fight-or-flight response in cultured liver cells. You inject these cells with cAMP. What outcome would you predict?

Answer 30

Increased glucose production from glycogen

Question 31

Suppose you are a research scientist studying the fight-or-flight response in cultured liver cells. You inject these cells with adrenaline. What outcome would you predict?

Answer 31

No change in glycogen mobilization

Question 32

Which component of the cytoskeleton is the smallest in diameter?

Answer 32

Microfilaments

Question 33

GCPRs: bind to, activate what

Answer 33

bind to heterotrimeric G proteins ligand binding to GPCRs activates G proteins

Question 34

Heterotrimeric G proteins (like RAS)

Answer 34

Membrane-associated proteins with 3 subunits Bind GDP (inactive) to GTP (active)

Question 35

Is activated adenylyl cyclase an effectivor

Answer 35

yes

Question 36

What is the pathway for GCPRs

Answer 36

activated receptor activate adenylyl cyclase converts ATP into cAMP which activates kinase A Kinase A phosphorylates proteins in the heart muscle

Question 37

Is cAMP a first messenger or second messenger

Answer 37

Second

Question 38

What is the difference between a first messenger and a second messenger

Answer 38

first messenger-ligand signal second messenger-small, soluble, non-protein molecule, relay the initial signal to target molecules inside the cell

Question 39

Difference between active form and inactive form

Answer 39

Active form-interaction and turned on Inactive form-no interaction, turned off

Question 40

Second messengers:

Answer 40

Affect many processes Amplify signal Regulate target enzymes

Question 41

What are the four steps in termination?

Answer 41

Transient (temp. bound signal) Devactives itself Get rid of cAMP Loses phosphates

Question 42

Ion channel receptors:

Answer 42

Channel proteins that allow ions to enter or leave a cell

Question 43

In a ligand-gated channel, how is it activated

Answer 43

nerotransmitters

Question 44

What are 3 effects of a signal

Answer 44

opening ion channels changing enzyme activity differential gene transcription

Question 45

Cell signaling over a long distance is known as: A. autocrine signaling. B. paracrine signaling. C. endocrine signaling. D. juxtacrine signaling.

Answer 45

endocrine signaling

Question 46

How many subunits make up a G protein? A. three B. two C. four D. The number is variable.

Answer 46

three (It is heterotrimeric, meaning that it has three subunits that are all different!)

Question 47

What happens to the alpha subunit of a G protein with GDP attached? A. It re-assembles with the beta and gamma subunits. B. It no longer activates an effector protein. C. It re-associates with the G protein–coupled receptor. D. All of these answer options are correct.

Answer 47

All correct

Question 48

Which one of the following initiates signal termination? A. the reduction of signal amplification B. the shut down of transcription C. the release of signal molecules from their receptors D. the shut down of translation

Answer 48

the release of signal molecules from their receptors

Question 49

Which of the following is characterized by a cell releasing a signal molecule into the environment, followed by a number of cells in the immediate vicinity responding? A. juxtacrine signaling B. autocrine signaling C. paracrine signaling D. endocrine signaling

Answer 49

paracrine signaling

Question 50

One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this? A. G protein-coupled receptors B. ligand-gated ion channels C. steroid receptors D. receptor kinases

Answer 50

receptor kinases

Question 51

The receptors for a group of signaling molecules known as growth factors are often A. ligand-gated ion channels. B. G protein-coupled receptors. C. receptor kinases.

Answer 51

receptor kinases

Question 52

An inhibitor of phosphodiesterase activity would have which of the following effects? A. decrease the amount of cAMP in the cytoplasm B. block the activation of G proteins in response to epinephrine binding to its receptor C. prolong the effect by maintaining elevated cAMP levels in the cytoplasm D. block the activation of protein kinase A

Answer 52

prolong the effect by maintaining elevated cAMP levels in the cytoplasm

Question 53

The epithelial cell junctions that, respectively, 1) restrict the extracellular movement of molecules across an epithelium, 2) maintain tissue integrity and strength, and 3) allow the passage of small molecules between adjacent cells are: A. gap junctions, desmosomes, and tight junctions B. desmosomes, tight junctions, and gap junctions C. tight junctions, gap junctions, tight junctions D. gap junctions, tight junctions, desmosomes E. tight junctions, desmosomes, gap junctions

Answer 53

tight junctions, desmosomes, gap junctions

Question 54

Which of the following cell junctions is designed in such a manner to create a “tube” connecting one cell to the other such as in cardiomyocytes? A. gap junctions B. tight junctions C. desmosomes

Answer 54

gap junctions

Question 55

Cadherin is a component of which two types of cell junctions? A. Adheres junctions B. Desmosomes C. Gap junctions D. B+C E. A+B

Answer 55

A+B

Question 56

What is the difference between a tissue and organ?

Answer 56

Cells make tissues and tissues make an organ, and different organs present in the body make an organ system. The tissue is capable of performing the simple task while organs are known for operating the complex one.

Question 57

In an ion-gated channel what activates the channel? What breaks down the activator?

Answer 57

Acetylcholine Acetylcholinesterase