Question 1

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

Question 2

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

Question 3

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 D)
F) All of the above

Question 4

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) A) and C)

Question 5

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

Question 6

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.E) B) and D)
F) A) and C)

Question 7

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 cyclaseE) All of the above
F) B) and D)

Question 8

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 C)
F) B) and D)

Question 9

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 activityE) A) and B)
F) None of the above

Question 10

What does it mean to say that a signal is transduced?

Accepted Answer

A)   The signal enters the cell directly and binds to a receptor inside.
B)   The physical form of the signal changes as it passes from the cell membrane to the ultimate intracellular target.
C)   The signal is amplified, such that even one signal molecule evokes a large response.
D)   The signal triggers a sequence of phosphorylation events inside the cell.E) A) and B)
F) None of the above

Question 11

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

Accepted Answer

A)   C. elegans does not naturally use apoptosis, but can be induced to do so in the laboratory.
B)   C. elegans undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development.
C)   C. elegans has large cells wherein apoptosis is easily observed without the aid of a microscope.
D)   As C. elegans ages, its cells die progressively until the whole organism is dead.E) All of the above
F) C) and D)

Question 12

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 kinasesE) B) and C)
F) All of the above

Question 13

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 D)

Question 14

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)   activation of a developmental pathway found in the worm but not in humans
B)   a form of cancer in which there is insufficient apoptosis
C)   formation of molecular pores in the mitochondrial outer membrane
D)   excess skin lossE) A) and D)
F) All of the above

Question 15

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 matrixE) All of the above
F) None of the above

Question 16

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 C)
F) B) and D)

Question 17

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 AMPE) B) and D)
F) B) and C)

Question 18

Which of the following statements describes the events of apoptosis?

Accepted Answer

A)   The cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled.
B)   The cell's DNA and organelles become fragmented, the cell dies, and it is phagocytized.
C)   The cell's DNA and organelles become fragmented, the cell shrinks and forms blebs, and the cell's parts are packaged in vesicles that are digested by specialized cells.
D)   The cell's nucleus and organelles are lysed, and then the cell enlarges and bursts.E) None of the above
F) B) and C)

Question 19

Cells that are infected, damaged, or have reached the end of their functional life span often undergo "programmed cell death." This controlled cell suicide is called apoptosis. Select the appropriate description of this event on a cell's life cycle.

Accepted Answer

A)   Apoptosis is regulated by cell surface receptors that signal when a cell has reached its density-dependent limits.
B)   During apoptosis, dying cells leak out their contents, including digestive enzymes that also destroy healthy cells.
C)   During apoptosis, cellular agents chop up the DNA and fragment the organelles and other cytoplasmic components of a cell.
D)   Each cell organelle has protein signals that initiate the breakdown of the organelle's components, which leads to cell death.E) A) and C)
F) B) and D)

Question 20

Use the following figure to answer the question.

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)   hormonesE) A) and B)
F) All of the above

Exam 11: Cell Communication

The activation of receptor tyrosine kinases is characterized by

Correct Answer
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Correct Answer
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Correct Answer
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Cells that are infected, damaged, or have reached the end of their functional life span often undergo "programmed cell death." This controlled cell suicide is called apoptosis. Select the appropriate description of this event on a cell's life cycle.

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

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?

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

Which of the following statements describes the events of apoptosis?

Correct Answer
verified

Which of the following is a correct association?

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

Use the following figure to answer the question. In the figure, the dots in the space between the two structures represent which of the following?

Correct Answer
verified

What does it mean to say that a signal is transduced?

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

Correct Answer
verified

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

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

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?

Correct Answer
verified

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

Correct Answer
verified

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

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

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

Correct Answer
verified

Exam 11: Cell Communication

The activation of receptor tyrosine kinases is characterized by

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Cells that are infected, damaged, or have reached the end of their functional life span often undergo "programmed cell death." This controlled cell suicide is called apoptosis. Select the appropriate description of this event on a cell's life cycle.

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

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?

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

Which of the following statements describes the events of apoptosis?

Correct AnswerverifiedShow Answer

Which of the following is a correct association?

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

Use the following figure to answer the question. In the figure, the dots in the space between the two structures represent which of the following?

Correct AnswerverifiedShow Answer

What does it mean to say that a signal is transduced?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

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

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?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

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

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

Correct AnswerverifiedShow Answer

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