Question 1

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 acidE) A) and B)
F) C) and D)

Question 2

Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. Which of the following conditions is required for the target organ to respond to a particular hormone?

Accepted Answer

A)   Cells in the target organ must modify their plasma membranes to allow the hormone to enter the cytoplasm.
B)   The target organ must be the same as the organ that produced the hormone.
C)   The target organ must have the opposite mating type of the organ that produced the hormone.
D)   The target organ must have receptors that recognize and bind the hormone molecule.E) None of the above
F) All of the above

Question 3

Protein kinase is an enzyme that functions in which of the following ways?

Accepted Answer

A)   as a second messenger molecule
B)   as a receptor for various signal molecules
C)   activates or inactivates other proteins by adding a phosphate group to them
D)   activates a G proteinE) All of the above
F) A) and B)

Question 4

A signal transmitted via phosphorylation of a series of proteins is generally associated with which of the following events?

Accepted Answer

A)   conformational changes to each protein in the series
B)   binding of a hormone to an intracellular receptor
C)   activation of a ligand-gated ion channel
D)   production of ATP in the process of signal transductionE) A) and B)
F) C) and D)

Question 5

Why does testosterone, a lipid-soluble signaling 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.E) A) and C)
F) C) and D)

Question 6

Which of the following statements is true of steroid receptors?

Accepted Answer

A)   The receptor molecules are themselves lipids or glycolipids.
B)   The receptor may be inside the nucleus of a target cell.
C)   The unbound steroid receptors are quickly recycled by lysosomes.
D)   Steroid receptors are typically bound to the external surface of the nuclear membrane.E) None of the above
F) A) and D)

Question 7

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

Accepted Answer

A)   phosphorylated proteins
B)   cAMP
C)   adenylyl cyclase
D)   activated G proteinsE) A) and C)
F) None of the above

Question 8

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.E) C) and D)
F) All of the above

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 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 membraneE) A) and B)
F) C) and D)

Question 10

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.E) A) and B)
F) None of the above

Question 11

The activation of receptor tyrosine kinases is characterized by

Accepted Answer

A)   dimerization and phosphorylation.
B)   dimerization and IP₃ binding.
C)   a phosphorylation cascade.
D)   GTP hydrolysis.E) B) and D)
F) B) and C)

Question 12

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 signaling molecules.E) C) and D)
F) A) and D)

Question 13

In the nematode C. elegans, ced-9 prevents apoptosis in a normal cell in which of the following ways?

Accepted Answer

A)   It prevents the caspase activity of ced-3 and ced-4.
B)   Ced-9 remains inactive until it is signaled by ced-3 and other caspases.
C)   Ced-9 cleaves to produce ced-3 and ced-4.
D)   Ced-9 prevents blebbing by its action on the cell membrane.E) B) and C)
F) None of the above

Question 14

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

Accepted Answer

A)   cAMP
B)   G protein
C)   GTP
D)   adenylyl cyclaseE) B) and D)
F) A) and B)

Question 15

One of the major categories of receptors in the plasma membrane functions 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 kinasesE) A) and B)
F) A) and C)

Question 16

Which of the following provides the best evidence that cell-signaling pathways evolved early in the history of life?

Accepted Answer

A)   Cell-signaling pathways are seen in "primitive" cells such as bacteria and yeast.
B)   Bacteria and yeast cells signal each other in a process called quorum sensing.
C)   Signal transduction molecules identified in distantly related organisms are similar.
D)   Most signals in all types of cells are received by cell surface receptors.E) B) and D)
F) None of the above

Question 17

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 transcriptionE) A) and C)
F) A) and B)

Question 18

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 signaling pathways
C)   adenylyl cyclase activity
D)   receptor tyrosine kinase activityE) C) and D)
F) A) and D)

Question 19

Which of the following is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells?

Accepted Answer

A)   hormonal signaling
B)   autocrine signaling
C)   paracrine signaling
D)   synaptic signalingE) A) and D)
F) None of the above

Question 20

Lipid-soluble signaling molecules, such as aldosterone, 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)   only target cells have enzymes that break down aldosterone.
D)   only in target cells is aldosterone able to initiate the phosphorylation cascade that turns genes on.E) A) and B)
F) A) and C)

Exam 11: Cell Communication

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

Correct Answer
verified

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

Correct Answer
verified

Which of the following statements is true of steroid receptors?

Correct Answer
verified

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

Correct Answer
verified

What is a primary function of transcription factors?

Correct Answer
verified

In the nematode C. elegans, ced-9 prevents apoptosis in a normal cell in which of the following ways?

Correct Answer
verified

Protein phosphorylation is commonly involved with all of the following except

Correct Answer
verified

Which of the following provides the best evidence that cell-signaling pathways evolved early in the history of life?

Correct Answer
verified

What are scaffolding proteins?

Correct Answer
verified

A signal transmitted via phosphorylation of a series of proteins is generally associated with which of the following events?

Correct Answer
verified

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

Correct Answer
verified

Correct Answer
verified

Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. Which of the following conditions is required for the target organ to respond to a particular hormone?

Correct Answer
verified

Which of the following is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells?

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

Protein kinase is an enzyme that functions in which of the following ways?

Correct Answer
verified

The activation of receptor tyrosine kinases is characterized by

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

Exam 11: Cell Communication

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Which of the following statements is true of steroid receptors?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

What is a primary function of transcription factors?

Correct AnswerverifiedShow Answer

In the nematode C. elegans, ced-9 prevents apoptosis in a normal cell in which of the following ways?

Correct AnswerverifiedShow Answer

Protein phosphorylation is commonly involved with all of the following except

Correct AnswerverifiedShow Answer

Which of the following provides the best evidence that cell-signaling pathways evolved early in the history of life?

Correct AnswerverifiedShow Answer

What are scaffolding proteins?

Correct AnswerverifiedShow Answer

A signal transmitted via phosphorylation of a series of proteins is generally associated with which of the following events?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. Which of the following conditions is required for the target organ to respond to a particular hormone?

Correct AnswerverifiedShow Answer

Which of the following is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Protein kinase is an enzyme that functions in which of the following ways?

Correct AnswerverifiedShow Answer

The activation of receptor tyrosine kinases is characterized by

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Correct Answer
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