Question 1

Lipid-soluble signal molecules, such as testosterone, cross the membranes of all cells but affect only target cells because

Accepted Answer

A) only target cells retain the appropriate DNA segments. 
B) intracellular receptors are present only in target cells. 
C) most cells lack the Y chromosome required. 
D) only target cells possess the cytosolic enzymes that transduce the testosterone. 
E) only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor. 
A) only target cells retain the appropriate DNA segments. 
B) intracellular receptors are present only in target cells. 
C) most cells lack the Y chromosome required. 
D) only target cells possess the cytosolic enzymes that transduce the testosterone. 
E) only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor. B

Question 2

An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?

Accepted Answer

A) tyrosine kinases 
B) serine/threonine kinases 
C) phosphodiesterase 
D) phospholipase C 
E) adenylyl cyclase 
A) tyrosine kinases 
B) serine/threonine kinases 
C) phosphodiesterase 
D) phospholipase C 
E) adenylyl cyclase D

Question 3

Which of the substances below is a protein that can hold several other relay proteins as it binds to an activated membrane receptor?

Accepted Answer

A) active transcription factor 
B) third messenger 
C) ligand 
D) scaffolding protein 
E) protein kinase 
A) active transcription factor 
B) third messenger 
C) ligand 
D) scaffolding protein 
E) protein kinase D

Question 4

The general name for an enzyme that transfers phosphate groups from ATP to a protein is

Accepted Answer

A) phosphorylase. 
B) phosphatase. 
C) protein kinase. 
D) ATPase. 
E) protease. 
A) phosphorylase. 
B) phosphatase. 
C) protein kinase. 
D) ATPase. 
E) protease.

Question 5

The termination phase of cell signaling requires which of the following?

Accepted Answer

A) removal of the receptor 
B) activation of a different set of relay molecules 
C) converting ATP to camp 
D) reversing the binding of signal molecule to the receptor 
E) apoptosis 
A) removal of the receptor 
B) activation of a different set of relay molecules 
C) converting ATP to camp 
D) reversing the binding of signal molecule to the receptor 
E) apoptosis

Question 6

Which of the following is True of the mating signal transduction pathway in yeast?

Accepted Answer

A) The pathway carries an electrical signal between mating cell types. 
B) Mating type a secretes a signal called a factor. 
C) The molecular details of the pathway in yeast and in animals are very different. 
D) Scientists think the pathway evolved long after multicellular creatures appeared on Earth. 
E) The signal reception, transduction, and response occur in the nucleus. 
A) The pathway carries an electrical signal between mating cell types. 
B) Mating type a secretes a signal called a factor. 
C) The molecular details of the pathway in yeast and in animals are very different. 
D) Scientists think the pathway evolved long after multicellular creatures appeared on Earth. 
E) The signal reception, transduction, and response occur in the nucleus.

Question 7

In general, a signal transmitted via phosphorylation of a series of proteins

Accepted Answer

A) brings a conformational change to each protein. 
B) requires binding of a hormone to a cytosol receptor. 
C) cannot occur in yeasts because they lack protein phosphatases. 
D) requires phosphorylase activity. 
E) allows target cells to change their shape and therefore their activity. 
A) brings a conformational change to each protein. 
B) requires binding of a hormone to a cytosol receptor. 
C) cannot occur in yeasts because they lack protein phosphatases. 
D) requires phosphorylase activity. 
E) allows target cells to change their shape and therefore their activity.

Question 8

When a cell releases a signal molecule into the environment and a number of cells in the immediate vicinity respond, this type of signaling is

Accepted Answer

A) typical of hormones. 
B) autocrine signaling. 
C) paracrine signaling. 
D) endocrine signaling. 
E) synaptic signaling. 
A) typical of hormones. 
B) autocrine signaling. 
C) paracrine signaling. 
D) endocrine signaling. 
E) synaptic signaling.

Question 9

Which of the following describes cell communication systems?

Accepted Answer

A) 
Cell signaling evolved more recently than systems such as the immune system of vertebrates. 
B) Communicating cells are usually close together. 
C) Most signal receptors are bound to the outer membrane of the nuclear envelope. 
D) Lipid phosphorylation is a major mechanism of signal transduction. 
E) In response to a signal, the cell may alter activities by changes in cytosol activity or in transcription of RNA. 
A) 
Cell signaling evolved more recently than systems such as the immune system of vertebrates. 
B) Communicating cells are usually close together. 
C) Most signal receptors are bound to the outer membrane of the nuclear envelope. 
D) Lipid phosphorylation is a major mechanism of signal transduction. 
E) In response to a signal, the cell may alter activities by changes in cytosol activity or in transcription of RNA.

Question 10

One of the major categories of receptors in the plasma membrane reacts by forming dimmers, adding phosphate groups, then activating relay proteins. Which type does this?

Accepted Answer

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

Question 11

Which of the following statements is True?

Accepted Answer

A) When signal molecules first bind to receptor tyrosine kinases, the receptors phosphorylate a number of nearby molecules. 
B) In response to some G-protein-mediated signals, a special type of lipid molecule associated with the plasma membrane is cleaved to form IP3 and calcium. 
C) In most cases, signal molecules interact with the cell at the plasma membrane and then enter the cell and eventually the nucleus. 
D) Toxins such as those that cause botulism and cholera interfere with the ability of activated G proteins to hydrolyze GTP to GDP, resulting in phosphodiesterase activity in the absence of an appropriate signal molecule. 
E) Protein kinase A activation is one possible result of signal molecules binding to G protein-linked receptors. 
A) When signal molecules first bind to receptor tyrosine kinases, the receptors phosphorylate a number of nearby molecules. 
B) In response to some G-protein-mediated signals, a special type of lipid molecule associated with the plasma membrane is cleaved to form IP3 and calcium. 
C) In most cases, signal molecules interact with the cell at the plasma membrane and then enter the cell and eventually the nucleus. 
D) Toxins such as those that cause botulism and cholera interfere with the ability of activated G proteins to hydrolyze GTP to GDP, resulting in phosphodiesterase activity in the absence of an appropriate signal molecule. 
E) Protein kinase A activation is one possible result of signal molecules binding to G protein-linked receptors.

Question 12

The description above illustrates which of the following?

Accepted Answer

A) Just because a drug acts on one type of receptor does not mean that it will act on another type. 
B) Beta blockers can be used effectively on any type of muscle. 
C) Beta adrenergic receptors must be in the cytosol if they are going to influence contraction and relaxation. 
D) The chemical structures of the beta 1 and beta 2 receptors must have the same active sites. 
A) Just because a drug acts on one type of receptor does not mean that it will act on another type. 
B) Beta blockers can be used effectively on any type of muscle. 
C) Beta adrenergic receptors must be in the cytosol if they are going to influence contraction and relaxation. 
D) The chemical structures of the beta 1 and beta 2 receptors must have the same active sites.

Question 13

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

Accepted Answer

A) design a compound that mimics epinephrine and can bind to the epinephrine receptor. 
B) design a compound that stimulates cAMP production in liver cells. 
C) design a compound to stimulate G protein activity in liver cells. 
D) design a compound that increases phosphodiesterase activity. 
E) All of the above are possible approaches. 
A) design a compound that mimics epinephrine and can bind to the epinephrine receptor. 
B) design a compound that stimulates cAMP production in liver cells. 
C) design a compound to stimulate G protein activity in liver cells. 
D) design a compound that increases phosphodiesterase activity. 
E) All of the above are possible approaches.

Question 14

The activation of receptor tyrosine kinases is characterized by

Accepted Answer

A) dimerization and phosphorylation. 
B) IP₃ binding. 
C) a phosphorylation cascade. 
D) GTP hydrolysis. 
E) channel protein shape change. 
A) dimerization and phosphorylation. 
B) IP₃ binding. 
C) a phosphorylation cascade. 
D) GTP hydrolysis. 
E) channel protein shape change.

Question 15

Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of

Accepted Answer

A) phosphorylated proteins. 
B) GTP. 
C) cAMP. 
D) adenylyl cyclase. 
E) activated G proteins. 
A) phosphorylated proteins. 
B) GTP. 
C) cAMP. 
D) adenylyl cyclase. 
E) activated G proteins.

Question 16

Chemical signal pathways

Accepted Answer

A) operate in animals, but not in plants. 
B) are absent in bacteria, but are plentiful in yeast. 
C) involve the release of hormones into the blood. 
D) often involve the binding of signal molecules to a protein on the surface of a target cell. 
E) use hydrophilic molecules to activate enzymes. 
A) operate in animals, but not in plants. 
B) are absent in bacteria, but are plentiful in yeast. 
C) involve the release of hormones into the blood. 
D) often involve the binding of signal molecules to a protein on the surface of a target cell. 
E) use hydrophilic molecules to activate enzymes.

Question 17

Use the following information to answer the following questions.
Affinity chromatography is a method that can be used to purify cell-surface receptors, while they retain their hormone-binding ability. A ligand (hormone) for a receptor of interest is chemically linked to polystyrene beads. A solubilized preparation of membrane proteins is passed over a column containing these beads. Only the receptor binds to the beads.
-This method of affinity chromatography would be expected to collect which of the following?

Accepted Answer

A) molecules of the hormone 
B) molecules of purified receptor 
C) G proteins 
D) assorted membrane proteins 
E) hormone-receptor complexes 
A) molecules of the hormone 
B) molecules of purified receptor 
C) G proteins 
D) assorted membrane proteins 
E) hormone-receptor complexes

Question 18

The coupled G protein most likely interacts with this receptor

Accepted Answer

A) at the NH3 end 
B) at the COO- end 
C) along the exterior margin 
D) along the interior margin 
E) at the loop between H5 and H6 
A) at the NH3 end 
B) at the COO- end 
C) along the exterior margin 
D) along the interior margin 
E) at the loop between H5 and H6

Question 19

An inhibitor of phosphodiesterase activity would have which of the following effects?

Accepted Answer

A) block the response of epinephrine 
B) decrease the amount of cAMP in the cytoplasm 
C) block the activation of G proteins in response to epinephrine binding to its receptor 
D) prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm 
E) block the activation of protein kinase A 
A) block the response of epinephrine 
B) decrease the amount of cAMP in the cytoplasm 
C) block the activation of G proteins in response to epinephrine binding to its receptor 
D) prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm 
E) block the activation of protein kinase A

Question 20

Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins?

Accepted Answer

A) G-protein-linked receptor signaling 
B) ligand-gated ion channel signaling 
C) adenylyl cyclase activity 
D) phosphatase activity 
E) receptor tyrosine kinase activity 
A) G-protein-linked receptor signaling 
B) ligand-gated ion channel signaling 
C) adenylyl cyclase activity 
D) phosphatase activity 
E) receptor tyrosine kinase activity

Exam 11: Cell Communication

Lipid-soluble signal molecules, such as testosterone, cross the membranes of all cells but affect only target cells because

An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?

Which of the substances below is a protein that can hold several other relay proteins as it binds to an activated membrane receptor?

The general name for an enzyme that transfers phosphate groups from ATP to a protein is

The termination phase of cell signaling requires which of the following?

Which of the following is True of the mating signal transduction pathway in yeast?

In general, a signal transmitted via phosphorylation of a series of proteins

When a cell releases a signal molecule into the environment and a number of cells in the immediate vicinity respond, this type of signaling is

Which of the following describes cell communication systems?

One of the major categories of receptors in the plasma membrane reacts by forming dimmers, adding phosphate groups, then activating relay proteins. Which type does this?

Which of the following statements is True?

The description above illustrates which of the following?

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

The activation of receptor tyrosine kinases is characterized by

Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of

Chemical signal pathways

The coupled G protein most likely interacts with this receptor

An inhibitor of phosphodiesterase activity would have which of the following effects?

Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins?

Introduction: Themes in the Study of Life

The Chemical Context of Life

Water and the Fitness of the Environment

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: Harvesting Chemical Energy

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

Control 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 Introduction to Animal Diversity

Invertebrates

Vertebrates

Plant Structure, Growth, and Development

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

Conservation Biology and Restoration Ecology

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