Question 1

Certain receptor tyrosine kinases (RTKs)  that promote excessive cell division are found at high levels in various cancer cells. HER2 is an RTK that is present at excessively high levels in some breast cancer cells. Herceptin is a protein that binds to HER2 and inhibits cell division. Herceptin may be an effective treatment for breast cancer treatment under which of the following conditions?

Accepted Answer

A)   If injection of HER2 in the patient's cancer cells inhibits cell division.
B)   If the patient's cancer cells have excessive levels of HER2.
C)   If the patient lacks functional HER2 proteins.
D)   If the patient has excessive levels of other RTKs in cancer cells.E) B) and C)
F) A) and D)

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

Question 3

Which of the following occurs during apoptosis?

Accepted Answer

A)   lysis of the cell
B)   direct contact between signaling cells
C)   fragmentation of the DNA
D)   release of proteases outside the cellE) B) and C)
F) C) and D)

Question 4

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

Accepted Answer

A)   intracellular receptor
B)   G protein-coupled receptor
C)   phosphorylated receptor tyrosine kinase dimer
D)   ligand-gated ion channelE) A) and C)
F) B) and C)

Question 5

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 C)
F) A) and D)

Question 6

Which of the following statements best describes how steroid hormones access their receptors within target cells?

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 and nuclear membranes.
D)   Steroid hormones first bind to a steroid activator and this complex is transported across the cell membrane by a steroid transport protein.E) None of the above
F) B) and C)

Question 7

A type of localized signaling in which a cell secretes a signal molecule that affects neighboring cells is best described as which of the following?

Accepted Answer

A)   hormonal signaling
B)   autocrine signaling
C)   paracrine signaling
D)   cell-cell contact-dependent signalingE) C) and D)
F) A) and C)

Question 8

A drug could inhibit the release of glucose from liver cells by having which of the following effects on the liver cells?

Accepted Answer

A)   activating epinephrine receptors
B)   increasing cAMP production
C)   blocking G protein activity
D)   increasing glycogen phosphorylase activityE) A) and B)
F) A) and C)

Question 9

If an animal cell suddenly loses the ability to produce GTP, what will most likely happen to its signaling system?

Accepted Answer

A)   It will not be able to activate G proteins on the cytoplasmic side of the plasma membrane.
B)   It will be able to carry out reception and transduction but would not be able to respond to a signal.
C)   It will use ATP instead of GTP to activate G proteins on the cytoplasmic side of the plasma membrane.
D)   It will not be able to activate receptor tyrosine kinases.E) A) and C)
F) A) and B)

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) None of the above
F) All of the above

Question 11

Which of the following statements best explains why testosterone, a lipid-soluble signaling molecule that crosses the membranes of all cells, affects only target cells?

Accepted Answer

A)   Only target cells retain the appropriate genes regulated by testosterone.
B)   Only target cells contain the intracellular receptors for testosterone.
C)   Only target cells possess the cytosolic enzymes that transduce the signal from testosterone to adenylyl cyclase.
D)   Testosterone initiates a phosphorylation cascade only in target cells.E) B) and C)
F) A) and D)

Question 12

Which of the following statements describes a likely effect of a drug that inhibits testosterone binding to its receptor in human cells?

Accepted Answer

A)   The cytosolic levels of cAMP would decrease.
B)   The expression of certain genes would increase or decrease.
C)   The cytosolic calcium concentration would increase.
D)   The activity of G proteins would decrease.E) A) and B)
F) A) and C)

Question 13

Protein phosphorylation is commonly involved with which of the following?

Accepted Answer

A)   ligand binding by receptor tyrosine kinases
B)   activation of G protein-coupled receptors
C)   activation of protein kinase molecules
D)   release of Ca2+ from the ER lumenE) All of the above
F) B) and C)

Question 14

Binding of a growth factor to its receptor is most likely to immediately activate which of the following molecules?

Accepted Answer

A)   protein kinase
B)   adenylyl cyclase
C)   cAMP
D)   phosphorylaseE) None of the above
F) All of the above

Question 15

Which of the following statements best describes why phosphorylation cascades are useful in cellular signal transduction?

Accepted Answer

A)   they are species specific
B)   they always lead to the same cellular response
C)   they amplify the original signal many times
D)   they counter the harmful effects of phosphatasesE) B) and C)
F) A) and C)

Question 16

Which of the sequences below best describes the sequential steps (numbered 1-5)  in a signal transduction pathway that utilizes a G protein-coupled receptor?
1)  The signal-receptor complex activates a G protein.
2)  Protein kinases are activated.
3)  A signal molecule binds to a receptor.
4)  Target proteins are phosphorylated.
5)  cAMP is produced.

Accepted Answer

A)   1, 2, 3, 4, 5
B)   3, 1, 2, 4, 5
C)   3, 1, 5, 2, 4
D)   1, 2, 5, 3, 4E) All of the above
F) B) and C)

Question 17

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

Accepted Answer

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

Question 18

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

Question 19

Consider the following pathway:
Epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP
Which of the following molecules serves as the second messenger in this pathway?

Accepted Answer

A)   cAMP
B)   G protein
C)   adenylyl cyclase
D)   G protein-coupled receptorE) A) and B)
F) A) and C)

Question 20

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogen and other steroid hormones. How can one hormone, such as estrogen, mediate so many different effects?

Accepted Answer

A)   Estrogen is produced in very large concentration by nearly every tissue of the body.
B)   Each cell responds in the same way when steroids bind to the cell surface.
C)   Estrogen is kept away from the surface of any cells, not able to bind it at the surface.
D)   Estrogen binds to specific receptors inside many kinds of cells, each with different responses.E) A) and B)
F) B) and C)

Exam 9: Cellular Signaling

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

Correct Answer
verified

Protein phosphorylation is commonly involved with which of the following?

Correct Answer
verified

If an animal cell suddenly loses the ability to produce GTP, what will most likely happen to its signaling system?

Correct Answer
verified

Correct Answer
verified

Which of the following statements best explains why testosterone, a lipid-soluble signaling molecule that crosses the membranes of all cells, affects only target cells?

Correct Answer
verified

Which of the following statements best describes why phosphorylation cascades are useful in cellular signal transduction?

Correct Answer
verified

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogen and other steroid hormones. How can one hormone, such as estrogen, mediate so many different effects?

Correct Answer
verified

Which of the following statements describes a likely effect of a drug that inhibits testosterone binding to its receptor in human cells?

Correct Answer
verified

A drug could inhibit the release of glucose from liver cells by having which of the following effects on the liver cells?

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

What is a primary function of transcription factors?

Correct Answer
verified

Which of the following occurs during apoptosis?

Correct Answer
verified

Which of the following statements best describes how steroid hormones access their receptors within target cells?

Correct Answer
verified

Consider the following pathway: Epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP Which of the following molecules serves as the second messenger in this pathway?

Correct Answer
verified

Binding of a growth factor to its receptor is most likely to immediately activate which of the following molecules?

Correct Answer
verified

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

Correct Answer
verified

Correct Answer
verified

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

Correct Answer
verified

A type of localized signaling in which a cell secretes a signal molecule that affects neighboring cells is best described as which of the following?

Correct Answer
verified

Exam 9: Cellular Signaling

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

Correct AnswerverifiedShow Answer

Protein phosphorylation is commonly involved with which of the following?

Correct AnswerverifiedShow Answer

If an animal cell suddenly loses the ability to produce GTP, what will most likely happen to its signaling system?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following statements best explains why testosterone, a lipid-soluble signaling molecule that crosses the membranes of all cells, affects only target cells?

Correct AnswerverifiedShow Answer

Which of the following statements best describes why phosphorylation cascades are useful in cellular signal transduction?

Correct AnswerverifiedShow Answer

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogen and other steroid hormones. How can one hormone, such as estrogen, mediate so many different effects?

Correct AnswerverifiedShow Answer

Which of the following statements describes a likely effect of a drug that inhibits testosterone binding to its receptor in human cells?

Correct AnswerverifiedShow Answer

A drug could inhibit the release of glucose from liver cells by having which of the following effects on the liver cells?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

What is a primary function of transcription factors?

Correct AnswerverifiedShow Answer

Which of the following occurs during apoptosis?

Correct AnswerverifiedShow Answer

Which of the following statements best describes how steroid hormones access their receptors within target cells?

Correct AnswerverifiedShow Answer

Consider the following pathway: Epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP Which of the following molecules serves as the second messenger in this pathway?

Correct AnswerverifiedShow Answer

Binding of a growth factor to its receptor is most likely to immediately activate which of the following molecules?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

A type of localized signaling in which a cell secretes a signal molecule that affects neighboring cells is best described as which of the following?

Correct AnswerverifiedShow Answer

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