Question 1

What are scaffolding proteins?

Accepted Answer

A)  Microtubule arrays that allow lipid-soluble hormones to get from the cell membrane to the nuclear pores. 
B)  Large molecules to which several relay proteins attach to facilitate cascade effects. 
C)  Relay proteins that orient receptors and their ligands in appropriate directions to facilitate complex formation. 
D)  Proteins that enter the nucleus of a cell to regulate transcription. 
A)  Microtubule arrays that allow lipid-soluble hormones to get from the cell membrane to the nuclear pores. 
B)  Large molecules to which several relay proteins attach to facilitate cascade effects. 
C)  Relay proteins that orient receptors and their ligands in appropriate directions to facilitate complex formation. 
D)  Proteins that enter the nucleus of a cell to regulate transcription.

Question 2

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

Accepted Answer

A)  binding of G proteins to G protein-coupled receptors 
B)  ligand-gated ion channel signalling pathways 
C)  adenylyl cyclase activity 
D)  receptor tyrosine kinase activity 
A)  binding of G proteins to G protein-coupled receptors 
B)  ligand-gated ion channel signalling pathways 
C)  adenylyl cyclase activity 
D)  receptor tyrosine kinase activity

Question 3

What is a primary function of transcription factors?

Accepted Answer

A)  They regulate the synthesis of DNA in response to a signal. 
B)  They convert ATP into cAMP. 
C)  They control gene expression. 
D)  They regulate the release of calcium from the endoplasmic reticulum. 
A)  They regulate the synthesis of DNA in response to a signal. 
B)  They convert ATP into cAMP. 
C)  They control gene expression. 
D)  They regulate the release of calcium from the endoplasmic reticulum.

Question 4

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

Accepted Answer

A)  protein kinase activity 
B)  adenylyl cyclase activity 
C)  cAMP activity 
D)  phosphorylase activity 
A)  protein kinase activity 
B)  adenylyl cyclase activity 
C)  cAMP activity 
D)  phosphorylase activity

Question 5

Many G protein-coupled receptors contain seven transmembrane α-helical domains. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior surface or on the cytosolic surface of the membrane. The loop on the cytosolic side between helices 5 and 6 is usually substantially longer than the others. Where would you expect to find the carboxyl end of the protein?

Accepted Answer

A)  at the exterior surface 
B)  at the cytosolic surface 
C)  connected with the loop at H5 and H6 
D)  embedded in the phospholipid bilayer of the membrane 
A)  at the exterior surface 
B)  at the cytosolic surface 
C)  connected with the loop at H5 and H6 
D)  embedded in the phospholipid bilayer of the membrane

Question 6

Protein phosphorylation is commonly involved with all of the following except

Accepted Answer

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

Question 7

Which of the following statements describes a likely effect of a drug designed that inhibits the cellular response to testosterone?

Accepted Answer

A)  The cytoplasmic levels of cAMP would decrease. 
B)  The transcription of certain genes would decrease. 
C)  The cytosolic calcium concentration would increase. 
D)  The activity of G proteins would decrease. 
A)  The cytoplasmic levels of cAMP would decrease. 
B)  The transcription of certain genes would decrease. 
C)  The cytosolic calcium concentration would increase. 
D)  The activity of G proteins would decrease.

Question 8

Scientists have found that extracellular matrix components may induce specific gene expression in embryonic tissues such as the liver and testes. For this to happen, there must be direct communication between the extracellular matrix and the developing cells. Which kind of transmembrane protein would most likely be involved in this kind of induction?

Accepted Answer

A)  integrins 
B)  fibronectins 
C)  actin microfilaments 
D)  receptor tyrosine kinases 
A)  integrins 
B)  fibronectins 
C)  actin microfilaments 
D)  receptor tyrosine kinases

Question 9

Many G protein-coupled receptors contain seven transmembrane α-helical domains. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior surface or on the cytosolic surface of the membrane. The loop on the cytosolic side between helices 5 and 6 is usually substantially longer than the others. Where would a coupled G protein most likely interact with this receptor?

Accepted Answer

A)  at the amino end 
B)  at the carboxyl end 
C)  along the exterior margin 
D)  at the loop between H5 and H6 
A)  at the amino end 
B)  at the carboxyl end 
C)  along the exterior margin 
D)  at the loop between H5 and H6

Question 10

Not all intercellular signals require transduction. Which one of the following signals would be processed without transduction?

Accepted Answer

A)  a lipid-soluble signal 
B)  a signal that is weakly bound to a nucleotide 
C)  a signal that binds to a receptor in the cell membrane 
D)  a signal that binds to the extracellular matrix 
A)  a lipid-soluble signal 
B)  a signal that is weakly bound to a nucleotide 
C)  a signal that binds to a receptor in the cell membrane 
D)  a signal that binds to the extracellular matrix

Question 11

Why does testosterone, a lipid-soluble signalling molecule that crosses the membranes of all cells, affect only target cells?

Accepted Answer

A)  Only target cells retain the appropriate genes regulated by testosterone. 
B)  Intracellular receptors for testosterone are present only in target cells. 
C)  Only target cells possess the cytosolic enzymes that transduce the signal from testosterone to adenylyl cyclase. 
D)  Only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor. 
A)  Only target cells retain the appropriate genes regulated by testosterone. 
B)  Intracellular receptors for testosterone are present only in target cells. 
C)  Only target cells possess the cytosolic enzymes that transduce the signal from testosterone to adenylyl cyclase. 
D)  Only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor.

Question 12

Which of the following amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction?

Accepted Answer

A)  tyrosines 
B)  glycine and histidine 
C)  serine and threonine 
D)  glycine and glutamic acid 
A)  tyrosines 
B)  glycine and histidine 
C)  serine and threonine 
D)  glycine and glutamic acid

Question 13

Which of the following statements is true of signal molecules?

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, enter the cell, and eventually enter the nucleus. 
D)  Protein kinase A activation is one possible result of signal molecules binding to G protein-coupled 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, enter the cell, and eventually enter the nucleus. 
D)  Protein kinase A activation is one possible result of signal molecules binding to G protein-coupled receptors.

Question 14

In which of the following ways do plant hormones differ from hormones in animals?

Accepted Answer

A)  Plant hormones frequently travel through the air as a gas. 
B)  Animal hormones are only local regulators. 
C)  Plant hormones commonly travel through the soil from one plant to another. 
D)  Animal hormones typically travel from the hormone producing cell to an adjacent responding cell through gap junctions. 
A)  Plant hormones frequently travel through the air as a gas. 
B)  Animal hormones are only local regulators. 
C)  Plant hormones commonly travel through the soil from one plant to another. 
D)  Animal hormones typically travel from the hormone producing cell to an adjacent responding cell through gap junctions.

Question 15

Consider this pathway:
Adrenaline → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP
The second messenger in this pathway is ________.

Accepted Answer

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

Question 16

The receptors for steroid hormones are located inside the cell instead of the membrane surface like most other signal receptors. How do steroids gain access to their receptors?

Accepted Answer

A)  Steroid hormone receptors undergo conformational changes that relocate them on the membrane surface. 
B)  Both steroid hormones and their receptors are produced by the same cells. 
C)  Steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane. 
D)  Steroid hormones first bind to a steroid activator and this complex is transported across the cell membrane by a steroid transport protein. 
A)  Steroid hormone receptors undergo conformational changes that relocate them on the membrane surface. 
B)  Both steroid hormones and their receptors are produced by the same cells. 
C)  Steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane. 
D)  Steroid hormones first bind to a steroid activator and this complex is transported across the cell membrane by a steroid transport protein.

Question 17

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

Accepted Answer

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

Question 18

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)  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)  adenylyl cyclase activity and the conversion of cAMP to AMP

Question 19

-In the figure, the dots in the space between the two structures represent which of the following?

Accepted Answer

A)  receptor molecules 
B)  signal transducers 
C)  neurotransmitters 
D)  hormones 
A)  receptor molecules 
B)  signal transducers 
C)  neurotransmitters 
D)  hormones

Question 20

Which observation suggested to Sutherland (1971 Nobel Prize winner) the involvement of a second messenger in adrenaline's effect on liver cells?

Accepted Answer

A)  Receptor studies indicated that adrenaline was a ligand. 
B)  Glycogen breakdown was observed only when adrenaline was administered to intact cells. 
C)  Glycogen breakdown was observed when adrenaline and glycogen phosphorylase were combined in a cell-free system. 
D)  Adrenaline was known to have different effects on many types of cells. 
A)  Receptor studies indicated that adrenaline was a ligand. 
B)  Glycogen breakdown was observed only when adrenaline was administered to intact cells. 
C)  Glycogen breakdown was observed when adrenaline and glycogen phosphorylase were combined in a cell-free system. 
D)  Adrenaline was known to have different effects on many types of cells.

Exam 11: Cell Communication

What are scaffolding proteins?

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

What is a primary function of transcription factors?

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

Protein phosphorylation is commonly involved with all of the following except

Which of the following statements describes a likely effect of a drug designed that inhibits the cellular response to testosterone?

Not all intercellular signals require transduction. Which one of the following signals would be processed without transduction?

Why does testosterone, a lipid-soluble signalling molecule that crosses the membranes of all cells, affect only target cells?

Which of the following amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction?

Which of the following statements is true of signal molecules?

In which of the following ways do plant hormones differ from hormones in animals?

Consider this pathway: Adrenaline → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP The second messenger in this pathway is ________.

The receptors for steroid hormones are located inside the cell instead of the membrane surface like most other signal receptors. How do steroids gain access to their receptors?

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

Which of the following is a correct association?

-In the figure, the dots in the space between the two structures represent which of the following?

Which observation suggested to Sutherland (1971 Nobel Prize winner) the involvement of a second messenger in adrenaline's effect on liver cells?

Evolution, the Themes of Biology, and Scientific Inquiry

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

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Viruses

Dna Tools and 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 Colonised 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

Vascular 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 Signalling

Nervous Systems

Sensory and Motor Mechanisms

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