Deck 9: Cell Signaling

Question 1

Which is the CORRECT order for these steps in cell signaling?

A)signal transduction, receptor activation, response
B)response, signal transduction, termination
C)receptor activation, response, signal transduction
D)receptor activation, signal transduction, response

Answer 1

D

Question 2

The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on:

A)the location of the tissue or organ with respect to the circulatory path.
B)the membrane potential of the cells of the target organ.
C)the presence of the appropriate receptors on the cells of the target tissue or organ.
D)nothing. All hormones of the body are able to stimulate all cell types because hormones are powerful and nonspecific.

Answer 2

C

Question 3

Which of the following is NOT an essential element involved in communication between all cells?

A)responding cell
B)signaling molecule
C)second messenger
D)receptor protein

Answer 3

C

Question 4

List the four essential components of cell communication, and describe their functions.

Question 5

Signal transduction results in:

A)a change in the conformation of the receptor protein.
B)a response by the cell.
C)production of more signal molecules.
D)termination of the signal.

Question 6

Which is NOT one of the steps in cell signaling?

A)signal transduction
B)obtaining a high density of signaling molecules
C)receptor activation
D)signal termination
E)cellular response

Question 7

In which of the following is cell signaling prevented?

A)The nicotine in cigarette smoke binds to and activates the acetylcholine receptor in plasma membranes of neurons in the brain.
B)Proteins on the surface of cells in taste buds called umami receptors bind to glutamates and nucleotides in food, which changes the membrane potential of these cells and tells the brain, "This is savory."
C)Allergy medicines, which are called antihistamines, bind to and block histamine receptors to keep fluids in capillaries that would normally be released and cause stuffy noses and watery eyes.

Question 8

Which of the following is NOT part of the general response of cells during cellular communication?

A)The cell does not return to its normal activities after the signal has exerted its effect.
B)Receptors on the outside of the cell bind to specific signal molecules.
C)A cell-surface receptor molecule becomes activated by binding to a molecular signal.
D)An activated cell-surface receptor transfers the signal to the interior of the cell.
E)The signal is transmitted inside the cell and amplified as a series of proteins are activated in sequence, affecting cellular activities according to the type of signal involved.

Question 9

Choose from the following terms to fill in the blanks in the CORRECT order. A. ligand
B) signaling cell
C) receptor
D) responding cell
In communication between cells, the _____ produces the signaling molecule, also known as the _____; the _____ produces the _____, to which the signaling molecule binds,

A)B, A, D, C
B)A, B, C, D
C)B, C, A, D
D)D, C, B, A

Question 10

Which of the following is a cellular response to signal transduction?

A)a change in the proteins found in the cytosol
B)the release of more signal molecules
C)a change in the activity of an enzyme
D)All of these choices are correct.

Question 11

In cell communication, which one of the following is a requirement of the responding cell?

A)It must be a eukaryotic cell.
B)It must produce signaling molecules.
C)It must have receptor proteins.
D)It must be a prokaryotic cell.

Question 12

To have communication between cells, you must have a:

A)receptor.
B)signaling molecule.
C)responding cell.
D)All of these choices are correct.

Question 13

Signaling pathways have been conserved in a wide range of organisms.

Question 14

A protein on a cell surface that binds to a signaling molecule is an example of which of the following elements of cellular communication?

A)a signaling cell
B)a signaling molecule
C)a receptor protein
D)a responding cell
E)None of the other answer options is correct.

Question 15

A cell that responds to an environmental condition by the release of a chemical is an example of which of the following elements of cellular communication?

A)a signaling cell
B)a signaling molecule
C)a receptor protein
D)a responding cell
E)None of the other answer options is correct.

Question 16

During the signal transduction process, the signal often triggers a signal transduction cascade. For example, an activated receptor activates hundreds of protein A. Each activated protein A activates hundreds of protein B and so on until a cellular response occurs. What purpose does this cascade serve?

A)Having several intermediates allows for greater control of the response.
B)The cascade serves to amplify the signal, so one activated receptor can have a significant response.
C)Having a cascade allows the cell to respond to different signals.
D)The cascade makes signaling easier to shut off or terminate.

Question 17

Which of the following statements about communication among bacteria is CORRECT?

A)At low population density, a high concentration of signaling molecules involved in DNA uptake is typically observed.
B)Unlike communication among eukaryotes, no receptor molecule is required in communication among bacteria.
C)Small peptides can stimulate a DNA-uptake response.
D)Cellular communication in bacteria is based on the same principles as communication among eukaryotic cells.

Question 18

Which of the following types of cellular activities can be a response to cell signaling?

A)Cell division is triggered.
B)Gene expression patterns are changed.
C)Enzyme activities are changed.
D)Cell signals are released to communicate with other cells.
E)All of these choices are correct.

Question 19

Nicotine from cigarette smoke acts as a ligand and associates with specific cells in the nervous system. Nicotine eventually produces feelings of pleasure and well-being. Below are the events that happen in the cellular response to nicotine. Place the events in the correct order to describe the steps in the signaling pathway. A. The acetylcholine receptor is an ion channel, and, when a ligand binds, the ion channel opens.
B) An influx of ions carries the signal to the reward areas of the brain.
C) Nicotine binds to the transmembrane protein that normally binds the neurotransmitter acetylcholine.
D) The signal causes release of dopamine in the brain, which causes good feelings.
E) Nicotine is quickly eliminated from the body (causing cravings for more cigarettes to produce good feelings).

A)C, A, B, D, E
B)A, D, B, C, E
C)B, A, C, D, E
D)C, D, B, A, E
E)Nicotine is quickly eliminated from the body (causing cravings for more cigarettes to produce good feelings).

Question 20

A chemical that binds to a cell and causes its activity to change is an example of which of the following elements of cellular communication?

A)a signaling cell
B)a signaling molecule
C)a receptor protein
D)a responding cell
E)None of the other answer options is correct.

Question 21

Vascular endothelial growth factor (abbreviated VEGF and pronounced "Veg-F") is a peptide signaling molecule related to platelet-derived growth factor. VEGF is important in the formation of the circulatory system because its signaling pathway causes the formation of new blood vessels in developing embryos during normal development. Tumors also produce and secrete VEGF, causing the formation of new blood vessels that supply these tumors. Given what you know about the different kinds of cell signaling and about VEGF, is VEGF a paracrine or an endocrine-signaling molecule? Justify your answer.

Question 22

Many scientists use chemical inhibitors to interfere with normal signaling pathways within eukaryotic cells. If such inhibitors are large, nonpolar molecules, what is the likely method of action of these chemical inhibitors?

A)These chemical inhibitors likely enter eukaryotic cells and interfere with components of the signal transduction pathway.
B)These chemical inhibitors likely enter the nucleus and prevent the transcription of the pathway of interest's target genes.
C)These chemical inhibitors likely bind to receptors and interfere with receptor activation or signal-receptor binding.
D)These chemical inhibitors likely interfere with the termination of signaling, so eukaryotic cells can't process new signals.

Question 23

You create a cell that has a mutation in a receptor protein that binds a signaling molecule, which is also produced by the same cell. When you overexpress the signaling molecule produced by this cell, nothing happens. What is defective in this cell?

A)endocrine signaling
B)contact-dependent signaling
C)paracrine signaling
D)autocrine signaling

Question 24

Which of the following types of cell signaling generally occurs between cells that are distant from each other?

A)paracrine
B)autocrine
C)endocrine
D)All of these choices are correct.

Question 25

Of the choices below, what is the MOST likely reason that paracrine signaling does not activate the cell that is producing the signaling molecule?

A)The concentration of the signaling molecule is not high enough.
B)The neighboring cells are too far away.
C)The cell does not have the proper receptor.
D)The cell's receptors have a mutation.

Question 26

Which of the following is a type of cell communication where the signaling molecule is released by the same cell that responds to the signal?

A)contact-dependent
B)paracrine
C)autocrine
D)endocrine
E)All of these choices are correct.

Question 27

The differentiation of embryonic stem cells into neurons and glial cells is a consequence of which type of cell signaling?

A)contact-dependent
B)paracrine
C)autocrine
D)endocrine
E)All of these choices are correct.

Question 28

Recall from the text the example of cell communication in Streptococcus pneumoniae: The rate of DNA uptake by pneumococcal cells increases sharply when they are at high density, due to changes in gene expression brought about by signaling between cells. If the pneumococcal cells did not express receptor proteins, how would the rate of DNA uptake be affected when the cells reach high density?

A)There would be no change in the rate of DNA uptake.
B)There would be a larger than normal increase in the rate of DNA uptake.
C)There would be a smaller than normal increase in the rate of DNA uptake.
D)There would be a decrease in the rate of DNA uptake.

Question 29

A cell can only respond to signals from other cells, not from the physical environment.

Question 30

Vascular endothelial growth factor (abbreviated VEGF and pronounced "Veg-F") is a peptide signaling molecule related to platelet-derived growth factor. VEGF is important in the formation of the circulatory system because its signaling pathway causes the formation of blood vessels in developing embryos during normal development. Tumors also produce and secrete VEGF, causing the formation of new blood vessels that supply these tumors. Given what you know about the different kinds of cell signaling and VEGF, which one of the following statements is TRUE?

A)VEGF is an endocrine-signaling molecule because it circulates through the bloodstream inside of platelets.
B)VEGF is an endocrine-signaling molecule because it is released from platelets into the bloodstream and is carried throughout the body, causing widespread activation of platelet-derived growth factor receptors on cells in a variety of tissues.
C)VEGF is a paracrine signaling molecule because it binds to receptors on cells at the site where new blood vessels are needed.

Question 31

Which of the following CORRECTLY lists the types of cellular communication from shortest to longest distance traveled by the signaling molecule to reach its responding cell?

A)paracrine, autocrine, endocrine
B)autocrine, endocrine, paracrine
C)autocrine, paracrine, endocrine
D)endocrine, paracrine, autocrine

Question 32

Platelet-derived growth factor (PDGF) is a signaling molecule that functions in which of the following types of cell signaling?

A)contact-dependent
B)paracrine
C)autocrine
D)endocrine
E)All of these choices are correct.

Question 33

Many diseases are the result of a problem with cell signaling. Which of the following diseases BEST exemplifies this fact?

A)cystic fibrosis, which is caused by a mutation in a channel protein, resulting in a buildup of mucus
B)congestive heart failure, which is caused by chronic high blood pressure due to excessive sodium intake
C)a specific type of cancer, which is caused by a truncated receptor that becomes stuck in the activated for.
D)familial hypercholesterolemia (high cholesterol in the blood), which is caused by a decrease in the number of receptors for cholesterol.

Question 34

The first event that happens after a signaling molecule binds to a receptor is:

A)the receptor transmits the message in a process called signal transduction.
B)there is a cellular response.
C)the receptor is activated.
D)the signal is quickly terminated to ensure a moderate response.

Question 35

Which type of cell signaling does not rely on the diffusion of a chemical signal molecule?

A)contact-dependent
B)paracrine
C)autocrine
D)endocrine
E)All of these choices are correct.

Question 36

Which of the following is TRUE about the Delta protein?

A)Delta is a transmembrane protein found in embryonic brain cells.
B)Delta is produced by embryonic stem cells as they differentiate into neurons in the brain.
C)Delta directly signals to a Notch transmembrane protein in adjacent cells.
D)Delta directs adjacent cells to differentiate into glial cells.
E)All of these choices are correct.

Question 37

Types of steroids include:

A)sex hormones such as estrogen and testosterone.
B)glucocorticoids that regulate blood glucose levels.
C)insect molting hormones.
D)lipid-soluble hormones derived from cholesterol.
E)All of these choices are correct.

Question 38

In many signaling pathways, once a signaling molecule binds to a receptor, the receptor becomes phosphorylated. This initial phosphorylation step BEST demonstrates:

A)receptor activation.
B)signal transduction.
C)cellular response.
D)termination.
E)either cellular response or signal transduction.

Question 39

A researcher introduces a signal produced by bacteria to eukaryotic cells that she is culturing in the laboratory. Remarkably, she notices that this signal results in an increase in eukaryotic gene expression. How is this possible?

A)This signal is likely similar in structure to ligands utilized by eukaryotic cells.
B)This signaling pathway might actually be used by both prokaryotes and eukaryotes.
C)This gene expression is likely independent of the presence of the prokaryotic signal.
D)This prokaryotic signal likely travels directly into eukaryotic cells and acts as a transcription factor.
E)The signal is either similar in structure to a ligand used by eukaryotes, or this signaling pathway is used by both prokaryotes and eukaryotes.

Question 40

Communication between neurons is an example of which type of cell signaling?

A)contact-dependent
B)paracrine
C)autocrine
D)endocrine
E)All of these choices are correct.

Question 41

Notch and Delta are both transmembrane proteins involved in cell communication in the developing nervous system of vertebrate animals. What makes Notch different from Delta?

A)Notch is a receptor, and Delta is a signaling molecule.
B)Notch is a signaling molecule, and Delta is a receptor.
C)Notch is required at higher density than Delta to alter cell fate.
D)All of these choices are correct.

Question 42

Imagine that a researcher is studying the embryonic development of mice that do not express the signal molecule Delta. What will likely be TRUE of these mice?

A)These mice will have more neurons compared with their normal counterparts.
B)These mice will have fewer neurons compared with their normal counterparts.
C)These mice will have more glia compared with their normal counterparts.
D)The mice will have fewer glia compared with their normal counterparts.
E)The mice will have fewer neurons and more glia compared with their normal counterparts.

Question 43

Cell signaling between two nerve cells can be thought of as an example of paracrine signaling because:

A)a signaling molecule (neurotransmitter)is released.
B)a receptor is activated.
C)the cells are in close proximity.
D)the responding cell releases more of the signaling molecule (neurotransmitter).

Question 44

Review the experiments by Kohler and Lipton described in Figure 9.5. What is the key difference between blood serum and blood plasma that affects their ability to help fibroblasts grow in culture?

A)Serum contains more platelet cells than plasma, and platelet cells promote cell growth.
B)Molecules found in serum promote cell growth; these molecules are not found in plasma.
C)Plasma contains more platelet cells than serum, and platelet cells inhibit cell growth.
D)Molecules found in plasma inhibit cell growth; these molecules are not found in serum.

Question 45

Which signaling system involves the LONGEST time interval between release of a signaling molecule and activation of a receptor?

A)autocrine
B)contact-dependent
C)paracrine
D)endocrine

Question 46

Signaling molecules involved in paracrine and autocrine signaling:

A)remain attached to the plasma membrane.
B)travel by diffusion.
C)travel in the circulatory system.

Question 47

Which of the following would NOT be considered a cell-surface receptor?

A)a receptor that binds a nonpolar steroid hormone and activates transcription
B)a receptor that allows ions to enter the cell when a ligand binds
C)a receptor that causes GDP to be exchanged for GTP in a G protein
D)a receptor that must form a dimer after binding the ligand to transmit a signal

Question 48

Growth factors, such as platelet-derived growth factor, function in _____ signaling.

A)autocrine
B)paracrine
C)endocrine
D)contact-dependent

Question 49

Cell signaling over a long distance is known as _____ signaling.

A)paracrine
B)endocrine
C)contact-dependent
D)autocrine

Question 50

Describe how a nonpolar steroid hormone receptor is different from a cell-surface receptor.

Question 51

In the developing nervous system, _____ is the signaling molecule that results in the differentiation of _____.

A)Notch; neurons
B)Notch; glial cells
C)Delta; glial cells
D)Delta; neurons

Question 52

A drug designed to inhibit the response of cells to the steroid testosterone would almost certainly result in which of the following?

A)lower levels of cAMP
B)a decrease in receptor kinase activity
C)a decrease in the transcription of certain genes
D)an increase in cytosolic calcium levels
E)a decrease in G protein activity

Question 53

Which one of the following would be found bound to the regulatory region of a gene?

A)steroid hormone receptor
B)MAP kinase
C)adenylyl cyclase
D)cAMP
E)protein kinase A

Question 54

The signaling molecule involved in contact-dependent cell signaling is a:

A)small soluble peptide.
B)neurotransmitter.
C)transmembrane protein.
D)growth factor.

Question 55

A researcher is evaluating the role of a growth factor during embryonic development. She notices that this factor functions in both neural development and limb development. How is that possible?

A)The effects of the growth factor may be concentration-dependent.
B)The effects of the growth factor may be dependent on location.
C)The growth factor may result in the transcription of different genes, depending on cell type.
D)The growth factor may be signaling through different transduction pathways.
E)All of these choices are possible explanations for the observations.

Question 56

Which of the following signaling molecules would you expect to travel the LONGEST distance in the human body?

A)testosterone
B)Delta
C)PDGF
D)neurotransmitters
E)Notch

Question 57

Based on the data provided in the two graphs shown in Figure 9.5, which method of culturing resulted in the greatest number of fibroblast cells on day 6?

A)fibroblasts cultured with serum
B)fibroblasts cultured with platelet proteins
C)fibroblasts cultured with plasma
D)The same results are obtained whether the fibroblasts are cultured with serum or with platelet proteins.

Question 58

What is a growth factor?

A)a small protein that influences cell growth and division
B)a signaling molecule involved in paracrine signaling
C)a soluble molecule that can alter gene expression in a cell
D)All of these choices are correct.

Question 59

Which of the following statements is FALSE regarding a neurotransmitter?

A)Neurotransmitters are typically dispersed over small distances.
B)Similar to Delta or Notch, neurotransmitters are usually attached to the cell surface.
C)Neurotransmitters can be growth factors.
D)Neurotransmitters play a role in muscle contraction.
E)Neurotransmitters are produced by neurons.

Question 60

Mammalian steroid hormones are signaling molecules that function in which of the following types of cell signaling?

A)paracrine
B)autocrine
C)endocrine
D)All of these choices are correct.

Question 61

Despite their differences, steroid hormones:

A)have the same effect on different types of cells.
B)bind to cell-surface receptors.
C)bind intracellular receptors to form complexes that enter the nucleus.
D)are hydrophilic small molecules that bind to intracellular receptors.
E)facilitate the initiation of translation by ribosomes.

Question 62

What does a ligand-gated channel do?

A)It binds small, nonpolar signaling molecules.
B)It activates a G protein.
C)It allows ions to move across the plasma membrane.
D)It triggers the activity of a phosphatase.

Question 63

Ion channels can be involved in cell signaling because:

A)they interact with G proteins.
B)they lead to receptor phosphorylation.
C)their signal is amplified in the cell by a series of phosphorylation events.
D)they receive signals from other cells and lead to a cellular response.
E)Ion channels are not involved in cell signaling.

Question 64

Which type of receptor is membrane-associated?

A)G protein-coupled receptor
B)receptor kinase
C)ligand-gated ion channel
D)intracellular receptor

Question 65

What is the cell's likely response to ligand binding to a steroid receptor located in the nucleus?

A)a change in gene expression
B)activation of a kinase
C)initiation of a signal transduction pathway
D)change in ion transport

Question 66

Which of the following would NOT be considered a cell-surface receptor?

A)a receptor that binds a nonpolar steroid hormone and activates transcription
B)a receptor that allows ions to enter the cell when a ligand binds
C)a receptor that causes GDP to be exchanged for GTP in a G protein
D)a receptor that forms a dimer after binding the ligand

Question 67

Which type of receptor is involved in rapid responses of muscle cells and neurons?

A)G protein-coupled receptor
B)receptor kinase
C)ligand-gated ion channel
D)intracellular receptor

Question 68

In the context of cell signaling, to what does the term ligand refer?

A)a signaling molecule
B)the extracellular domain of a receptor protein
C)the proteins activated as part of a signal transduction pathway
D)a type of gated channel

Question 69

Which type of receptor does NOT generally lead to a signaling cascade in the cell that involves the transfer of phosphate groups?

A)G protein-coupled receptor
B)receptor kinase
C)ligand-gated ion channel
D)intracellular receptor

Question 70

You strip off all proteins on the cell surface by using a protease (an enzyme that destroys proteins). Now, when you add a specific signaling molecule, the cell still responds. Why is this?

A)The signaling molecule doesn't need a receptor.
B)The signaling molecule is polar and can diffuse into the cell.
C)The receptor is in the interior of the cell.
D)The signaling molecule is nonpolar and binds a cell-surface receptor.

Question 71

Which type of protein adds a phosphate group to another molecule?

A)kinase
B)G protein
C)phosphatase
D)phosphorylase

Question 72

According to Figure 9.6, what is a key difference between cell signaling by a cell-surface receptor and cell signaling by an intracellular receptor?

A)Cell-surface receptors bind to specific signaling molecules; intracellular receptors bind any signaling molecule.
B)Cell-surface receptors typically bind to signaling molecules that are smaller than those bound by intracellular receptors.
C)Cell-surface receptors bind polar signaling molecules; intracellular receptors bind nonpolar signaling molecules.
D)Signaling molecules that bind to cell-surface receptors lead to cellular responses restricted to the cytoplasm; signaling molecules that bind to intracellular receptors lead to cellular responses restricted to the nucleus.
E)None of the other answer options is correct.

Question 73

Where would you expect to find the receptor for a nonpolar ligand?

A)on the cell surface
B)in the nucleus of the cell
C)in the cytosol
D)either in the nucleus of the cell or in the cytosol

Question 74

What determines the specificity of a receptor protein?

A)the cytoplasmic domain
B)the transmembrane domain
C)the ligand-binding site
D)the extracellular domain

Question 75

How are steroid hormone receptors and cell-surface receptors similar?

A)When bound to their ligand, both types enter the nucleus to activate transcription.
B)Both types cause G proteins to exchange GDP for GTP.
C)Both types undergo a conformational change when they bind to their ligand.
D)When activated, both types carry signals across the plasma membrane.

Question 76

Which type of receptor undergoes a conformational change upon activation?

A)G protein-coupled receptor
B)receptor kinase
C)ligand-gated ion channel
D)intracellular receptor

Question 77

Which one of the following is NOT a cell surface-type receptor?

A)G protein-coupled receptor
B)steroid receptor
C)ligand-gated receptor
D)receptor kinase

Question 78

Which type of cell-surface receptor undergoes changes in phosphorylation in response to binding of its ligand?

A)G protein-coupled receptor
B)receptor kinase
C)ligand-gated ion channel
D)both the G protein-coupled receptor and the receptor kinase

Question 79

How are steroid hormone receptors and cell-surface receptors similar?

Question 80

How does an "activated" receptor transfer information into the cell?

A)by altering the ligand-binding site of the receptor
B)through a conformational change of the receptor
C)by decreased phosphorylation of the receptor
D)by increased translation of the receptor