Question 1

Illustrate how a conformational change is critical in the two-step model of EGF function.

Accepted Answer

After dimerization of the receptor, the

Question 2

If protein kinase A is activated in a liver cell in response to glucagon binding to the $\beta$2-adrenergic receptor, which of the following will result?

Accepted Answer

A)  Glycogen synthesis will be turned on. 
B)  Glycogen degradation will be turned on. 
C)  Glucose synthesis will be turned off. 
D)  GLUT1 expression will be upregulated. 
A)  Glycogen synthesis will be turned on. 
B)  Glycogen degradation will be turned on. 
C)  Glucose synthesis will be turned off. 
D)  GLUT1 expression will be upregulated.

Question 3

Some breast cancers express estrogen receptors and are estrogen dependent. Tamoxifen is a chemotherapy agent used in the treatment of estrogen-responsive breast cancers. What is tamoxifen in relation to the estrogen receptor and why does it have this effect?

Accepted Answer

Tamoxifen is an antagonist of

Question 4

Explain how the conformational organization of a nuclear receptor homodimer allows it to recognize inverted repeat sequences of DNA.

Accepted Answer

The homodimer is organized hea

Question 5

Glycogen synthesis was monitored in a liver cell in the presence of glucagon binding to the
$\beta$2-adrenergic receptor and after its removal. How would the activity of enzymes involved in glycogen synthesis and glycogen degradation be altered if the experiment were carried out after the cells were treated with caffeine, an inhibitor of cAMP phosphodiesterase? Explain your reasoning.

Accepted Answer

If cAMP phosphodiesterase is inhibited,

Question 6

The levels of the second messenger involved in vasodilation are increased by and decreased by _.

Accepted Answer

A)  cGMP cyclase; guanylate phosphodiesterase 
B)  guanylate phosphodiesterase; cGMP cyclase 
C)  guanylate cyclase; cGMP phosphodiesterase 
D)  cGMP phosphodiesterase; guanylate cyclase 
A)  cGMP cyclase; guanylate phosphodiesterase 
B)  guanylate phosphodiesterase; cGMP cyclase 
C)  guanylate cyclase; cGMP phosphodiesterase 
D)  cGMP phosphodiesterase; guanylate cyclase

Question 7

If GRB2 were truncated so that the N-terminal domain was missing, the truncated protein would be unable to bind the

Accepted Answer

A)  phosphorylated Tyr of the SOS protein. 
B)  phosphorylated Tyr of the RTK substrate. 
C)  proline-rich sequence of the SOS protein. 
D)  protein-rich sequence of the RTK substrate. 
A)  phosphorylated Tyr of the SOS protein. 
B)  phosphorylated Tyr of the RTK substrate. 
C)  proline-rich sequence of the SOS protein. 
D)  protein-rich sequence of the RTK substrate.

Question 8

Predict which bond of a target protein would be cleaved by caspase 3 executioner enzyme.

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
A)  1 
B)  2 
C)  3 
D)  4

Question 9

An inhibitor of PTEN is accidentally ingested by an infant. The infant displays symptoms of hypoglycemia. How would inhibiting PTEN lead to this outcome?

Accepted Answer

PTEN removes the phosphate from PIP3 to

Question 10

When bound to GTP, GS $\alpha$  obtains a conformation that promotes interaction with

Accepted Answer

A)  adenylate cyclase. 
B)  PKA. 
C)  the G protein-coupled receptor. 
D)  phospholipase C. 
A)  adenylate cyclase. 
B)  PKA. 
C)  the G protein-coupled receptor. 
D)  phospholipase C.

Question 11

If a mutation occurred in SODD that prohibited its interaction with the DD of TNF receptor, the TNF receptor would

Accepted Answer

A)  no longer form a trimer. 
B)  no longer be able to release TNF-$\alpha$. 
C)  bind TRADD, even in the absence of TNF-$\alpha$. 
D)  bind NF$\kappa$B, even in the absence of TNF-$\alpha$. 
A)  no longer form a trimer. 
B)  no longer be able to release TNF-$\alpha$. 
C)  bind TRADD, even in the absence of TNF-$\alpha$. 
D)  bind NF$\kappa$B, even in the absence of TNF-$\alpha$.

Question 12

Outline the steps that occur in the shared pathway of glucagon and epinephrine signaling in a liver cell. Include the specific receptors, G protein subunits, upstream signaling protein, and second messengers.

Accepted Answer

Glucagon binds specifically to glucagon

Question 13

A Western blot analysis of the expression of estrogen receptors in ovarian tissues at different times of the estrous cycle showed approximately four times greater protein levels at day 2 compared with day 10 of the cycle. Which of the following may be true given these data?

Accepted Answer

A)  Estrogen is acting as an endocrine signal in the ovaries. 
B)  Estrogen is acting as an autocrine signal in the ovaries. 
C)  Ovaries only secrete estrogen early in the estrous cycle. 
D)  Ovarian tissue is responsive to estrogen only early in the estrous cycle. 
A)  Estrogen is acting as an endocrine signal in the ovaries. 
B)  Estrogen is acting as an autocrine signal in the ovaries. 
C)  Ovaries only secrete estrogen early in the estrous cycle. 
D)  Ovarian tissue is responsive to estrogen only early in the estrous cycle.

Question 14

When the regulatory subunit of PKA is bound to cAMP,

Accepted Answer

A)  it dissociates into monomers. 
B)  the pseudosubstrate is phosphorylated. 
C)  it cannot bind to catalytic subunit of PKA. 
D)  it is part of a tetramer. 
A)  it dissociates into monomers. 
B)  the pseudosubstrate is phosphorylated. 
C)  it cannot bind to catalytic subunit of PKA. 
D)  it is part of a tetramer.

Question 15

Which of the following compounds is a pharmaceutical adrenergic receptor agonist?

Accepted Answer

A)  dopamine 
B)  metoprolol 
C)  norepinephrine 
D)  clonidine 
A)  dopamine 
B)  metoprolol 
C)  norepinephrine 
D)  clonidine

Question 16

Below is shown the structure of a homodimer of the GR DNA-binding domain. Four areas are highlighted. Which is most likely to interact with DNA?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
A)  A 
B)  B 
C)  C 
D)  D

Question 17

Which of the following is a GTPase?

Accepted Answer

A)  G $\beta$ 
B)  G $\gamma$ 
C)  Gs $\alpha$ 
D)  G $\beta$ $\gamma$ 
A)  G $\beta$ 
B)  G $\gamma$ 
C)  Gs $\alpha$ 
D)  G $\beta$ $\gamma$

Question 18

On binding of insulin to the insulin receptor, the receptor becomes phosphorylated. What is the name of the protein that carried out this phosphorylation?

Accepted Answer

The insuli

Question 19

Construct a functional signal transduction pathway by placing the following actors in the correct order: 
A. upstream signaling protein
B. second messenger
C. receptor protein
D. first messenger
E. target proteins
F. downstream signaling protein

Accepted Answer

A)  D, E, C, A, B, F 
B)  C, D, A, B, F, E 
C)  D, C, A, B, F, E 
D)  D, C, B, A, F, E 
A)  D, E, C, A, B, F 
B)  C, D, A, B, F, E 
C)  D, C, A, B, F, E 
D)  D, C, B, A, F, E

Question 20

Consider a mutation in procaspase 3 that changes Asp28 to an amino acid that is no longer a substrate for autocleavage. This mutant would

Accepted Answer

A)  no longer be cleaved by caspase 8. 
B)  no longer obtain a quaternary structure. 
C)  be partially activated. 
D)  be fully activated. 
A)  no longer be cleaved by caspase 8. 
B)  no longer obtain a quaternary structure. 
C)  be partially activated. 
D)  be fully activated.

Exam 8: Cell Signaling Systems

Illustrate how a conformational change is critical in the two-step model of EGF function.

If protein kinase A is activated in a liver cell in response to glucagon binding to the β\betaβ 2-adrenergic receptor, which of the following will result?

Some breast cancers express estrogen receptors and are estrogen dependent. Tamoxifen is a chemotherapy agent used in the treatment of estrogen-responsive breast cancers. What is tamoxifen in relation to the estrogen receptor and why does it have this effect?

Explain how the conformational organization of a nuclear receptor homodimer allows it to recognize inverted repeat sequences of DNA.

The levels of the second messenger involved in vasodilation are increased by and decreased by _.

If GRB2 were truncated so that the N-terminal domain was missing, the truncated protein would be unable to bind the

Predict which bond of a target protein would be cleaved by caspase 3 executioner enzyme.

An inhibitor of PTEN is accidentally ingested by an infant. The infant displays symptoms of hypoglycemia. How would inhibiting PTEN lead to this outcome?

When bound to GTP, GS α\alphaα obtains a conformation that promotes interaction with

If a mutation occurred in SODD that prohibited its interaction with the DD of TNF receptor, the TNF receptor would

Outline the steps that occur in the shared pathway of glucagon and epinephrine signaling in a liver cell. Include the specific receptors, G protein subunits, upstream signaling protein, and second messengers.

A Western blot analysis of the expression of estrogen receptors in ovarian tissues at different times of the estrous cycle showed approximately four times greater protein levels at day 2 compared with day 10 of the cycle. Which of the following may be true given these data?

When the regulatory subunit of PKA is bound to cAMP,

Which of the following compounds is a pharmaceutical adrenergic receptor agonist?

Below is shown the structure of a homodimer of the GR DNA-binding domain. Four areas are highlighted. Which is most likely to interact with DNA?

Which of the following is a GTPase?

On binding of insulin to the insulin receptor, the receptor becomes phosphorylated. What is the name of the protein that carried out this phosphorylation?

Construct a functional signal transduction pathway by placing the following actors in the correct order: A. upstream signaling protein B. second messenger C. receptor protein D. first messenger E. target proteins F. downstream signaling protein

Consider a mutation in procaspase 3 that changes Asp28 to an amino acid that is no longer a substrate for autocleavage. This mutant would

Principles of Biochemistry

Physical Biochemistry: Energy Conversion, Water, and Membranes

Nucleic Acid Structure and Function

Protein Structure

Methods in Protein Biochemistry

Protein Function

Enzyme Mechanisms

Glycolysis: a Paradigm of Metabolic Regulation

The Citrate Cycle

Oxidative Phosphorylation

Photosynthesis

Carbohydrate Structure and Function

Carbohydrate Metabolism

Lipid Structure and Function

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Metabolic Integration

DNA Replication, Repair, and Recombination

RNA Synthesis, Processing, and Gene Silencing

Protein Synthesis, Posttranslational Modification, and Transport

Gene Regulation

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If protein kinase A is activated in a liver cell in response to glucagon binding to the $\beta$ 2-adrenergic receptor, which of the following will result?

When bound to GTP, G_S _$\alpha$ obtains a conformation that promotes interaction with