Question 1

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because

Accepted Answer

A)  they are species specific. 
B)  they always lead to the same cellular response. 
C)  they amplify the original signal manyfold. 
D)  they counter the harmful effects of phosphatases. 
E)  the number of molecules used is small and fixed. 
A)  they are species specific. 
B)  they always lead to the same cellular response. 
C)  they amplify the original signal manyfold. 
D)  they counter the harmful effects of phosphatases. 
E)  the number of molecules used is small and fixed.

Question 2

Because most receptors are membrane proteins, which of the following is usually true?

Accepted Answer

A)  They lead to changes in intracellular ion concentration. 
B)  They open and close in response to protein signals. 
C)  They are only attached to one membrane surface: exterior or interior. 
D)  They preferentially bind with lipid or glycolipid signal molecules. 
E)  They change their conformation after binding with signal polypeptides. 
A)  They lead to changes in intracellular ion concentration. 
B)  They open and close in response to protein signals. 
C)  They are only attached to one membrane surface: exterior or interior. 
D)  They preferentially bind with lipid or glycolipid signal molecules. 
E)  They change their conformation after binding with signal polypeptides.

Question 3

The following questions are based on the figure below:
  
-Which of the following types of signaling is represented in the figure?

Accepted Answer

A)  autocrine 
B)  paracrine 
C)  hormonal 
D)  synaptic 
E)  long distance 
A)  autocrine 
B)  paracrine 
C)  hormonal 
D)  synaptic 
E)  long distance

Question 4

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

Question 5

Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?

Accepted Answer

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

Question 6

Adenylyl cyclase has the opposite effect of which of the following?

Accepted Answer

A)  protein kinase 
B)  protein phosphatase 
C)  phosphodiesterase 
D)  phosphorylase 
E)  GTPase 
A)  protein kinase 
B)  protein phosphatase 
C)  phosphodiesterase 
D)  phosphorylase 
E)  GTPase

Question 7

The toxin of Vibrio cholerae causes profuse diarrhea because it

Accepted Answer

A)  modifies a G protein involved in regulating salt and water secretion. 
B)  decreases the cytosolic concentration of calcium ions, making the cells hypotonic. 
C)  binds with adenylyl cyclase and triggers the formation of cAMP. 
D)  signals IP₃ to act as a second messenger for the release of calcium. 
E)  modifies calmodulin and activates a cascade of protein kinases. 
A)  modifies a G protein involved in regulating salt and water secretion. 
B)  decreases the cytosolic concentration of calcium ions, making the cells hypotonic. 
C)  binds with adenylyl cyclase and triggers the formation of cAMP. 
D)  signals IP₃ to act as a second messenger for the release of calcium. 
E)  modifies calmodulin and activates a cascade of protein kinases.

Question 8

Protein phosphorylation is commonly involved with all of the following except

Accepted Answer

A)  regulation of transcription by extracellular signaling molecules. 
B)  enzyme activation. 
C)  activation of G protein-coupled receptors. 
D)  activation of receptor tyrosine kinases. 
E)  activation of protein kinase molecules. 
A)  regulation of transcription by extracellular signaling molecules. 
B)  enzyme activation. 
C)  activation of G protein-coupled receptors. 
D)  activation of receptor tyrosine kinases. 
E)  activation of protein kinase molecules.

Question 9

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

Question 10

Which of the following is a correct association?

Accepted Answer

A)  kinase activity and the addition of a tyrosine 
B)  phosphodiesterase activity and the removal of phosphate groups 
C)  GTPase activity and hydrolysis of GTP to GDP 
D)  phosphorylase activity and the catabolism of glucose 
E)  adenylyl cyclase activity and the conversion of cAMP to AMP 
A)  kinase activity and the addition of a tyrosine 
B)  phosphodiesterase activity and the removal of phosphate groups 
C)  GTPase activity and hydrolysis of GTP to GDP 
D)  phosphorylase activity and the catabolism of glucose 
E)  adenylyl cyclase activity and the conversion of cAMP to AMP

Question 11

Which of the following describes the events of apoptosis?

Accepted Answer

A)  The cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled. 
B)  Its DNA and organelles become fragmented, it dies, and it is phagocytized. 
C)  The cell dies and the presence of its fragmented contents stimulates nearby cells to divide. 
D)  Its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell self-digests. 
E)  Its nucleus and organelles are lysed, then the cell enlarges and bursts. 
A)  The cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled. 
B)  Its DNA and organelles become fragmented, it dies, and it is phagocytized. 
C)  The cell dies and the presence of its fragmented contents stimulates nearby cells to divide. 
D)  Its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell self-digests. 
E)  Its nucleus and organelles are lysed, then the cell enlarges and bursts.

Question 12

Receptor tyrosine kinases (RTKs)are found at high levels on various cancer cells. A protein, Herceptin, has been found to bind to an RTK known as HER2. This information can now be utilized in breast cancer treatment if which of the following is true?

Accepted Answer

A)  If Herceptin is found in the breast lymph nodes of the patient. 
B)  If HER2, administered by injection, is in sufficient concentration. 
C)  If the patient's cancer cells have detectable HER2. 
D)  If the patient's genome codes for the HER2 receptor. 
E)  If the patient's genome codes for the manufacture of Herceptin. 
A)  If Herceptin is found in the breast lymph nodes of the patient. 
B)  If HER2, administered by injection, is in sufficient concentration. 
C)  If the patient's cancer cells have detectable HER2. 
D)  If the patient's genome codes for the HER2 receptor. 
E)  If the patient's genome codes for the manufacture of Herceptin.

Question 13

The receptors for a group of signaling molecules known as growth factors are often

Accepted Answer

A)  ligand-gated ion channels. 
B)  G protein-coupled receptors. 
C)  cyclic AMP. 
D)  receptor tyrosine kinases. 
E)  neurotransmitters. 
A)  ligand-gated ion channels. 
B)  G protein-coupled receptors. 
C)  cyclic AMP. 
D)  receptor tyrosine kinases. 
E)  neurotransmitters.

Question 14

What is most likely to happen to an animal's target cells that lack receptors for local regulators?

Accepted Answer

A)  They might compensate by receiving nutrients via a factor. 
B)  They could develop normally in response to neurotransmitters instead. 
C)  They could divide but never reach full size. 
D)  They might not be able to multiply in response to growth factors from nearby cells. 
E)  Hormones would not be able to interact with target cells. 
A)  They might compensate by receiving nutrients via a factor. 
B)  They could develop normally in response to neurotransmitters instead. 
C)  They could divide but never reach full size. 
D)  They might not be able to multiply in response to growth factors from nearby cells. 
E)  Hormones would not be able to interact with target cells.

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 activates epinephrine receptors. 
B)  that increases cAMP production in liver cells. 
C)  to block G protein activity in liver cells. 
D)  that increases phosphorylase activity. 
E)  that keeps sugar molecules from crossing the plasma membrane of liver cells. 
A)  that activates epinephrine receptors. 
B)  that increases cAMP production in liver cells. 
C)  to block G protein activity in liver cells. 
D)  that increases phosphorylase activity. 
E)  that keeps sugar molecules from crossing the plasma membrane of liver cells.

Question 16

Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to

Accepted Answer

A)  the active site of an allosteric enzyme that binds to a specific substrate. 
B)  tRNA specifying which amino acids are in a polypeptide. 
C)  a metabolic pathway operating within a specific organelle. 
D)  an enzyme having an optimum pH and temperature for activity. 
E)  an antibody in the immune system. 
A)  the active site of an allosteric enzyme that binds to a specific substrate. 
B)  tRNA specifying which amino acids are in a polypeptide. 
C)  a metabolic pathway operating within a specific organelle. 
D)  an enzyme having an optimum pH and temperature for activity. 
E)  an antibody in the immune system.

Question 17

GTPase activity is involved in the regulation of signal transduction because it

Accepted Answer

A)  increases the available concentration of phosphate. 
B)  decreases the amount of G protein in the membrane. 
C)  hydrolyzes GTP binding to G protein. 
D)  converts cGMP to GTP. 
E)  phosphorylates protein kinases. 
A)  increases the available concentration of phosphate. 
B)  decreases the amount of G protein in the membrane. 
C)  hydrolyzes GTP binding to G protein. 
D)  converts cGMP to GTP. 
E)  phosphorylates protein kinases.

Question 18

Lipid-soluble signaling 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.

Question 19

One inhibitor of cGMP is Viagra. It provides a signal that leads to dilation of blood vessels and increase of blood in the penis, facilitating erection. Since cGMP is inhibited, the signal is prolonged. The original signal that is now inhibited would have

Accepted Answer

A)  hydrolyzed cGMP to GMP. 
B)  hydrolyzed GTP to GDP. 
C)  phosphorylated GDP. 
D)  dephosphorylated cGMP. 
E)  removed GMP from the cell. 
A)  hydrolyzed cGMP to GMP. 
B)  hydrolyzed GTP to GDP. 
C)  phosphorylated GDP. 
D)  dephosphorylated cGMP. 
E)  removed GMP from the cell.

Question 20

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.
-Beta 2 antagonist drugs might also be used most effectively for which of the following?

Accepted Answer

A)  cardiac arrhythmias 
B)  increased gastric acid production 
C)  neuropathy of the extremities 
D)  increasing low blood pressure 
E)  decreasing peristalsis 
A)  cardiac arrhythmias 
B)  increased gastric acid production 
C)  neuropathy of the extremities 
D)  increasing low blood pressure 
E)  decreasing peristalsis

Exam 11: Cell Communication

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because

Because most receptors are membrane proteins, which of the following is usually true?

The following questions are based on the figure below: -Which of the following types of signaling is represented in the figure?

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

Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?

Adenylyl cyclase has the opposite effect of which of the following?

The toxin of Vibrio cholerae causes profuse diarrhea because it

Protein phosphorylation is commonly involved with all of the following except

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

Which of the following is a correct association?

Which of the following describes the events of apoptosis?

Receptor tyrosine kinases (RTKs)are found at high levels on various cancer cells. A protein, Herceptin, has been found to bind to an RTK known as HER2. This information can now be utilized in breast cancer treatment if which of the following is true?

The receptors for a group of signaling molecules known as growth factors are often

What is most likely to happen to an animal's target cells that lack receptors for local regulators?

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

Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to

GTPase activity is involved in the regulation of signal transduction because it

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

One inhibitor of cGMP is Viagra. It provides a signal that leads to dilation of blood vessels and increase of blood in the penis, facilitating erection. Since cGMP is inhibited, the signal is prolonged. The original signal that is now inhibited would have

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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