Question 1

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?

Accepted Answer

A)  Enzymatic activity was proportional to the amount of calcium added to a cell-free extract. 
B)  Receptor studies indicated that epinephrine was a ligand. 
C)  Glycogen breakdown was observed only when epinephrine was administered to intact cells. 
D)  Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined. 
E)  Epinephrine was known to have different effects on different types of cells. 
A)  Enzymatic activity was proportional to the amount of calcium added to a cell-free extract. 
B)  Receptor studies indicated that epinephrine was a ligand. 
C)  Glycogen breakdown was observed only when epinephrine was administered to intact cells. 
D)  Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined. 
E)  Epinephrine was known to have different effects on different types of cells.

Question 2

Where do apoptotic signals come from?

Accepted Answer

A)  the nucleus only 
B)  the ER only 
C)  ligand binding only 
D)  mitochondrial protein leakage only 
E)  all of the above 
A)  the nucleus only 
B)  the ER only 
C)  ligand binding only 
D)  mitochondrial protein leakage only 
E)  all of the above

Question 3

In yeast signal transduction, the yeast cells

Accepted Answer

A)  must physically and directly interact. 
B)  produce signal molecules that change themselves so they can interact with one another. 
C)  produce response molecules that diffuse to other yeast cells. 
D)  secrete molecules that result in response by other yeast cells. 
E)  mate, after which the new cells secrete hybrid signals. 
A)  must physically and directly interact. 
B)  produce signal molecules that change themselves so they can interact with one another. 
C)  produce response molecules that diffuse to other yeast cells. 
D)  secrete molecules that result in response by other yeast cells. 
E)  mate, after which the new cells secrete hybrid signals.

Question 4

Using the yeast signal transduction pathways, both types of mating cells release the mating factors. These factors bind to specific receptors on the correct cells,

Accepted Answer

A)  which induce changes in the cells that lead to cell fusion. 
B)  which produce more of the a factor in a positive feedback. 
C)  then one cell nucleus binds the mating factors and produces a new nucleus in the opposite cell. 
D)  stimulating cell membrane disintegration, releasing the mating factors that lead to new yeast cells. 
E)  which in turn releases a growth factor that stimulates mitosis in both cells. 
A)  which induce changes in the cells that lead to cell fusion. 
B)  which produce more of the a factor in a positive feedback. 
C)  then one cell nucleus binds the mating factors and produces a new nucleus in the opposite cell. 
D)  stimulating cell membrane disintegration, releasing the mating factors that lead to new yeast cells. 
E)  which in turn releases a growth factor that stimulates mitosis in both cells.

Question 5

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?

Accepted Answer

A)  hormonal signaling 
B)  autocrine signaling 
C)  paracrine signaling 
D)  endocrine signaling 
E)  synaptic signaling 
A)  hormonal signaling 
B)  autocrine signaling 
C)  paracrine signaling 
D)  endocrine signaling 
E)  synaptic signaling

Question 6

Sutherland discovered that epinephrine signals

Accepted Answer

A)  a decrease in levels of cAMP as a result of bypassing the plasma membrane. 
B)  lower blood glucose by binding to liver cells. 
C)  interactions with insulin inside muscle cells. 
D)  interactions directly with glycogen phosphorylase. 
E)  elevation of cytosolic concentrations of cyclic AMP. 
A)  a decrease in levels of cAMP as a result of bypassing the plasma membrane. 
B)  lower blood glucose by binding to liver cells. 
C)  interactions with insulin inside muscle cells. 
D)  interactions directly with glycogen phosphorylase. 
E)  elevation of cytosolic concentrations of cyclic AMP.

Question 7

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?

Accepted Answer

A)  G protein-coupled receptors 
B)  ligand-gated ion channels 
C)  steroid receptors 
D)  receptor tyrosine kinases 
A)  G protein-coupled receptors 
B)  ligand-gated ion channels 
C)  steroid receptors 
D)  receptor tyrosine kinases

Question 8

What are scaffolding proteins?

Accepted Answer

A)  ladderlike proteins that allow receptor-ligand complexes to climb through cells from one position to another 
B)  microtubular protein arrays that allow lipid-soluble hormones to get from the cell membrane to the nuclear pores 
C)  large molecules to which several relay proteins attach to facilitate cascade effects 
D)  relay proteins that orient receptors and their ligands in appropriate directions to facilitate their complexing 
E)  proteins that can reach into the nucleus of a cell to affect transcription 
A)  ladderlike proteins that allow receptor-ligand complexes to climb through cells from one position to another 
B)  microtubular protein arrays that allow lipid-soluble hormones to get from the cell membrane to the nuclear pores 
C)  large molecules to which several relay proteins attach to facilitate cascade effects 
D)  relay proteins that orient receptors and their ligands in appropriate directions to facilitate their complexing 
E)  proteins that can reach into the nucleus of a cell to affect transcription

Question 9

If an adult person has a faulty version of the human analog to ced-4 of the nematode, which of the following is most likely to result?

Accepted Answer

A)  neurodegeneration 
B)  activation of a developmental pathway found in the worm but not in humans 
C)  a form of cancer in which there is insufficient apoptosis 
D)  webbing of fingers or toes 
E)  excess skin exfoliation 
A)  neurodegeneration 
B)  activation of a developmental pathway found in the worm but not in humans 
C)  a form of cancer in which there is insufficient apoptosis 
D)  webbing of fingers or toes 
E)  excess skin exfoliation

Question 10

Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger.

Accepted Answer

A)  cAMP 
B)  G protein 
C)  GTP 
D)  adenylyl cyclase 
E)  G protein-coupled receptor 
A)  cAMP 
B)  G protein 
C)  GTP 
D)  adenylyl cyclase 
E)  G protein-coupled receptor

Question 11

What explains the increased concentration of Ca⁺⁺ in the ER?

Accepted Answer

A)  Calcium ions are actively imported from the cytoplasm into the ER. 
B)  Calcium concentration is kept low in the cytoplasm because of its high usage level. 
C)  Calcium cannot enter the plasma membrane through ion channels. 
D)  Calcium levels in the blood or other body fluids are extremely low. 
E)  The Ca ions are recycled from other molecules in the ER. 
A)  Calcium ions are actively imported from the cytoplasm into the ER. 
B)  Calcium concentration is kept low in the cytoplasm because of its high usage level. 
C)  Calcium cannot enter the plasma membrane through ion channels. 
D)  Calcium levels in the blood or other body fluids are extremely low. 
E)  The Ca ions are recycled from other molecules in the ER.

Question 12

In research on aging (both cellular aging and organismal aging), it has been found that aged cells do not progress through the cell cycle as they had previously. Which of the following would provide evidence that this is related to cell signaling?

Accepted Answer

A)  Growth factor ligands do not bind as efficiently to receptors. 
B)  Their lower hormone concentrations elicit a lesser response. 
C)  cAMP levels change very frequently. 
D)  Enzymatic activity declines. 
E)  ATP production decreases. 
A)  Growth factor ligands do not bind as efficiently to receptors. 
B)  Their lower hormone concentrations elicit a lesser response. 
C)  cAMP levels change very frequently. 
D)  Enzymatic activity declines. 
E)  ATP production decreases.

Question 13

In the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function?

Accepted Answer

A)  formation of mating complexes 
B)  secretion of apoptotic signals 
C)  aggregation of bacteria that can cause cavities 
D)  secretion of substances that inhibit foreign bacteria 
E)  digestion of unwanted parasite populations 
A)  formation of mating complexes 
B)  secretion of apoptotic signals 
C)  aggregation of bacteria that can cause cavities 
D)  secretion of substances that inhibit foreign bacteria 
E)  digestion of unwanted parasite populations

Question 14

Why has C. elegans proven to be a useful model for understanding apoptosis?

Accepted Answer

A)  The animal has as many genes as complex organisms, but finding those responsible is easier than in a more complex organism. 
B)  The nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development. 
C)  This plant has a long-studied aging mechanism that has made understanding its death just a last stage. 
D)  While the organism ages, its cells die progressively until the whole organism is dead. 
E)  All of its genes are constantly being expressed so all of its proteins are available from each cell. 
A)  The animal has as many genes as complex organisms, but finding those responsible is easier than in a more complex organism. 
B)  The nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development. 
C)  This plant has a long-studied aging mechanism that has made understanding its death just a last stage. 
D)  While the organism ages, its cells die progressively until the whole organism is dead. 
E)  All of its genes are constantly being expressed so all of its proteins are available from each cell.

Question 15

If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound

Accepted Answer

A)  that mimics epinephrine and can bind to the epinephrine receptor. 
B)  that stimulates cAMP production in liver cells. 
C)  to stimulate G protein activity in liver cells. 
D)  that increases phosphodiesterase activity. 
E)  that does any of the above. 
A)  that mimics epinephrine and can bind to the epinephrine receptor. 
B)  that stimulates cAMP production in liver cells. 
C)  to stimulate G protein activity in liver cells. 
D)  that increases phosphodiesterase activity. 
E)  that does any of the above.

Question 16

Which of the following is the best explanation for the inability of a specific animal cell to reduce the Ca2⁺ concentration in its cytosol compared with the extracellular fluid?

Accepted Answer

A)  blockage of the synaptic signal 
B)  loss of transcription factors 
C)  insufficient ATP levels in the cytoplasm 
D)  low oxygen concentration around the cell 
E)  low levels of protein kinase in the cell 
A)  blockage of the synaptic signal 
B)  loss of transcription factors 
C)  insufficient ATP levels in the cytoplasm 
D)  low oxygen concentration around the cell 
E)  low levels of protein kinase in the cell

Question 17

Which of the following most likely would be an immediate result of growth factor binding to its receptor?

Accepted Answer

A)  protein kinase activity 
B)  adenylyl cyclase activity 
C)  GTPase activity 
D)  protein phosphatase activity 
E)  phosphorylase activity 
A)  protein kinase activity 
B)  adenylyl cyclase activity 
C)  GTPase activity 
D)  protein phosphatase activity 
E)  phosphorylase activity

Question 18

Use this information to respond to the following questions.
Humans have receptors for two kinds of beta adrenergic compounds such as catecholamines to control cardiac muscle contractions. Some are beta 1 receptors that promote increased heart rate. Other drugs, called beta blockers, slow heart rate. Smooth muscle cells, however, have beta 2 receptors, which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma.
-The use of beta 2 antagonist drugs may be useful in asthma because they may

Accepted Answer

A)  increase constriction of the skeletal muscle of the chest wall. 
B)  increase heart rate and therefore allow the patient to get more oxygen circulated. 
C)  dilate the bronchioles by relaxing their smooth muscle. 
D)  override the beta blockers that the patient is already taking. 
E)  obstruct all G protein-mediated receptors. 
A)  increase constriction of the skeletal muscle of the chest wall. 
B)  increase heart rate and therefore allow the patient to get more oxygen circulated. 
C)  dilate the bronchioles by relaxing their smooth muscle. 
D)  override the beta blockers that the patient is already taking. 
E)  obstruct all G protein-mediated receptors.

Question 19

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

Accepted Answer

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

Question 20

Which of the following is the best explanation for the fact that most transduction pathways have multiple steps?

Accepted Answer

A)  Most of the steps were already in place because they are steps in other pathways. 
B)  Multiple steps in a pathway require the least amount of ATP. 
C)  Multiple steps provide for greater possible amplification of a signal. 
D)  Each individual step can remove excess phosphate groups from the cytoplasm. 
E)  Each step can be activated by several G proteins simultaneously. 
A)  Most of the steps were already in place because they are steps in other pathways. 
B)  Multiple steps in a pathway require the least amount of ATP. 
C)  Multiple steps provide for greater possible amplification of a signal. 
D)  Each individual step can remove excess phosphate groups from the cytoplasm. 
E)  Each step can be activated by several G proteins simultaneously.

Exam 11: Cell Communication

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?

Where do apoptotic signals come from?

In yeast signal transduction, the yeast cells

Using the yeast signal transduction pathways, both types of mating cells release the mating factors. These factors bind to specific receptors on the correct cells,

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?

Sutherland discovered that epinephrine signals

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?

What are scaffolding proteins?

If an adult person has a faulty version of the human analog to ced-4 of the nematode, which of the following is most likely to result?

Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger.

What explains the increased concentration of Ca⁺⁺ in the ER?

In research on aging (both cellular aging and organismal aging), it has been found that aged cells do not progress through the cell cycle as they had previously. Which of the following would provide evidence that this is related to cell signaling?

In the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function?

Why has C. elegans proven to be a useful model for understanding apoptosis?

If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound

Which of the following is the best explanation for the inability of a specific animal cell to reduce the Ca2⁺ concentration in its cytosol compared with the extracellular fluid?

Which of the following most likely would be an immediate result of growth factor binding to its receptor?

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

Which of the following is the best explanation for the fact that most transduction pathways have multiple steps?

Introduction: Themes in the Study of Life

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

From Gene to Protein

Regulation of Gene Expression

Viruses

Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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