Deck 8: Cell Communication

Question 1

When epidermal growth factor binds to a(n)_______ receptor,the receptor phosphorylates itself,triggering a signal transduction pathway.

A)G-protein coupled
B)enzyme-linked
C)mechano
D)ligand-gated ion channel
E)thermo

Answer 1

B

Question 2

What happens immediately after a signaling molecule binds to its G-protein coupled receptor (GPCR)?

A)The signaling molecule enters the cell through its GPCR and travels to the nucleus,where it acts as a transcription factor.
B)The G protein exchanges GTP for GDP,and becomes inactivated.
C)The G protein exchanges GDP for GTP,and becomes inactivated.
D)The G protein exchanges GTP for GDP,and becomes activateD.
E)The G protein exchanges GDP for GTP,and becomes activated.

Answer 2

E

Question 3

A cell secretes a growth factor that binds to receptors on its own membrane preventing it from proliferating.This is an example of

A)direct intercellular signaling.
B)autocrine signaling.
C)endocrine signaling.
D)paracrine signaling.
E)contact-dependent signaling.

Answer 3

B

Question 4

Hormones are released from one cell and act on other cells in distant organs.This is an example of

A)paracrine signaling.
B)endocrine signaling.
C)contact-to-contact signaling.
D)autocrine signaling.
E)intercellular signaling.

Question 5

When the concentration of a ligand is equal to the K_D,

A)all of the ligands and receptors are bound to each other.
B)half of the ligands are bound to receptors.
C)all of the ligands are bound to receptors.
D)half of the receptors are bound to ligands.
E)all of the receptors are bound to ligands.

Question 6

A substrate binding to an enzyme is most similar to a signal molecule binding to a

A)G-protein.
B)receptor.
C)kinase.
D)second messenger.
E)transcriptional factor.

Question 7

The process through which cells can detect and respond to signals in their extracellular environment is

A)sensory response.
B)reception.
C)cell communication.
D)cell sensation.
E)transduction.

Question 8

Sodium ions move from one cardiac muscle cell to an adjacent cell causing them to contract in unison.This is an example of

A)contact-dependent signaling.
B)paracrine signaling.
C)endocrine signaling.
D)autocrine signaling.
E)direct intercellular signaling.

Question 9

Diabetics can be given insulin which binds to receptors on cells throughout the body increasing glucose uptake.Insulin is an example of a

A)G-protein.
B)signal.
C)transcription factor.
D)kinase.
E)response element.

Question 10

In some cases,just a few hormone molecules binding to the surface of a cell can trigger a very large response because

A)each hormone can bind to transcription factors simultaneously causing amplification of the signal.
B)the signal is amplified by activation of transcription factors that each catalyze multiple reactions.
C)each hormone can bind to multiple receptors simultaneously causing amplification of the signal.
D)the hormone triggers the cell to release more hormones,amplifying the signal.
E)the signal is amplified by activation of enzymes that each catalyze multiple reactions.

Question 11

G-protein coupled,enzyme-linked,and ligand-gated ion channel receptors are similar in that they

A)associate with a protein bound to GDP or GTP.
B)are all linked to protein kinase activation.
C)change their conformation when bound to a hormone.
D)bind similar hormones.
E)open ion channels.

Question 12

Following its initial activation,what becomes of a G protein?

A)The G-protein a subunit containing a GTP eventually reassociates with the G-protein bg dimer.
B)The G-protein a subunit GTP is hydrolyzed to GDP allowing reassociation of the G-protein a subunit and bg dimer.
C)The G-protein a subunit is digested and recycled.
D)It spontaneously loses activity within a few seconds.
E)The receptor becomes internalized.

Question 13

A cell responds to a signal it sent.This is an example of

A)contact-dependent signaling.
B)paracrine signaling.
C)endocrine signaling.
D)direct intercellular signaling.
E)autocrine signaling.

Question 14

A key is placed into a keyhole then turned and the door opens.When considering the components of cell signaling,the action of turning the key would best correspond to

A)the concentration of the hormone.
B)the cell response that occurs when the receptor binds the hormone.
C)the binding site of the receptor.
D)conformational change in the receptor once bound to the hormone.
E)signal transduction that occurs when the receptor binds the hormonE.

Question 15

If the concentration of a ligand is 100 times greater than the Kd of its receptor,

A)half of the receptors will be bound to a ligand.
B)few of the receptors will be bound to a ligand.
C)none of the receptors will be bound to a ligand.
D)most of the receptors will be bound to a liganD.

Question 16

During exposure to elevated glucose,a yeast cell will increase its uptake of glucose.Describe the mechanism by which the yeast sense the extracellular glucose.

A)By glucose diffusing into the nucleus and binding to transcription factors.
B)By the increase in energy outside the cell when the glucose is metabolized.
C)By glucose binding to glucose receptors.
D)By the increase in energy inside the cell when the glucose is metabolizeD.
E)By glucose uptake through glucose transporters.

Question 17

What do contact-dependent signaling and paracrine signaling have in common?

A)Cells release a signal that affects cells at long distances.
B)Cells bind a membrane bound signal on a neighboring cell.
C)Cells release a signal that affects it and neighboring cells.
D)Cells release a signal that affects neighboring cells.
E)Cells release a signal through gap junctions to affect neighboring cells.

Question 18

Insulin is secreted from the pancreas and acts on muscle cells to increase glucose uptake.This is an example of

A)contact-dependent signaling.
B)direct intercellular signaling.
C)autocrine signaling.
D)paracrine signaling.
E)endocrine signaling.

Question 19

After being fed glucose a cell increases its intracellular glucose concentrations by

A)increasing membrane glucose receptors.
B)increasing glucose synthesis in the cell.
C)decreasing glucose receptors on the cell.
D)increasing membrane glucose transporters.
E)decreasing glucose breakdown in the cell.

Question 20

A cell secretes a growth factor that binds to receptors on neighboring cells causing them to proliferate.This is an example of

A)paracrine signaling.
B)direct intercellular signaling.
C)endocrine signaling.
D)contact-dependent signaling.
E)autocrine signaling.

Question 21

One common feature with G-protein coupled,enzyme-linked,and growth factor receptors is that their activation leads to activation of protein kinases.

Question 22

Which signaling molecule is composed of $\alpha$ , $\beta$ ,and $\gamma$ subunits?

A)G-protein coupled receptor
B)ion-channel receptor
C)tyrosine kinase receptor
D)G-protein
E)ligand

Question 23

When epinephrine binds to its G-protein linked receptor,

A)adenylyl cyclase is activated producing cAMP.
B)kinase is activated producing calcium.
C)enzyme linked receptors is activated producing protein kinase.
D)kinase is activated producing transcription factor.
E)phospholipase C is activated producing diacylglyceridE.

Question 24

Epinephrine blocks the contraction of muscles in the airways.Which of the other activities of epinephrine is most likely to be regulated by the same type of pathway?

A)Contraction of smooth muscle cells in blood vessels
B)Increased sweating
C)Stimulation of heart muscle cell contraction
D)Inhibition of saliva production in salivary glands
E)Promotes the breakdown of glycogen in skeletal muscle cells

Question 25

After estrogen binds to receptors,these estrogen receptors gain activity of

A)transcription factor.
B)phosphatase.
C)GTP binding.
D)protein kinase.
E)phospholipasE.

Question 26

Cyclic AMP activates protein kinase C in producing a cell response.

Question 27

If epinephrine increases glycogen metabolism in muscle cells it would have the same function in brain cells.

Question 28

A phosphatase is capable of dephosphorylating molecules.What would this enzyme do in a signal transduction pathway that used a kinase cascade?

A)Phosphorylate a transcription factor.
B)Serve as a ligand for the receptor.
C)Activate the cascade.
D)Phosphorylate a receptor.
E)Turn off the cascadE.

Question 29

When a signal is released from one neuron and it moves to another neuron or to a muscle cell,the signal binds to a

A)ligand-gated ion channel.
B)voltage-gated ion channel.
C)nuclear receptor.
D)enzyme-linked receptor.
E)G-protein coupled receptor.

Question 30

Estrogen is a lipid soluble hormone that can easily cross membranes.Knowing this,what can be concluded about estrogen receptors?

A)The receptors would be linked to enzymes that triggered a kinase cascade.
B)The receptors would be found inside the cell.
C)The receptors would be coupled to a G-protein.
D)The receptors would be on the plasma membrane.
E)The receptors would also be lipid soluble and able to cross membranes.

Question 31

If you add the plant hormone auxin to one side of a plant the cells exposed to the auxin elongate.If you measured auxin levels in plant cells exposed to light what you would you expect to find?

A)They would be higher,causing the plant to bend towards the light.
B)They would be lower,causing the plant to bend away from the light.
C)They would be higher,causing the plant to bend away from the light.
D)They would be lower,causing the plant to bend towards the light.

Question 32

Whether a signaling molecule operates locally or over long distances,it must bind to a specific receptor to elicit a cellular response.

Question 33

Patients who have type 2 diabetes no longer express genes when exposed to insulin.How might this phenomenon be explained?

A)The nucleus of their cells are altered so that insulin can not bind.
B)The insulin signal transduction pathway becomes permanently activated.
C)Transcription factors normally activated by insulin remain off.
D)Insulin can no longer bind to the insulin receptor because the receptor is mutateD.
E)The signal transduction pathways in the cells no longer exist.

Question 34

In terms of cell signaling,estrogen in animal cells works in a similar fashion as the plant hormone auxin via binding to intracellular receptors.

Question 35

Smooth muscle cells in the airways relax while those in the blood vessels contract in response to the hormone epinephrine.What would you expect to be different in these two types of cells exposed to epinephrine?

A)Types of proteins expressed
B)Exposure to epinephrine released by neighboring cells
C)Activation of protein kinases
D)Presence of epinephrine receptors
E)Rate of metabolism

Question 36

Patients who have type 2 diabetes no longer respond normally to insulin.This symptom would be best explained by

A)the signal transduction pathways in the cells no longer exist.
B)Type 2 diabetics do not produce insulin.
C)the insulin receptors on their cells have mutated.
D)the nucleus of their cells are altered so that insulin can not binD.
E)their cells express less insulin receptor.

Question 37

The production of second messengers in signal transduction offers at least two advantages,speed and

A)specificity.
B)amplification.
C)one-to-one stoichiometry.
D)reversibility.
E)affinity.

Question 38

G proteins and Ras are activated when bound to GDP.

Question 39

Auxin is a plant hormone that causes cells to shorten and allow plant growing tips to move toward the sun.