Question 1

Calmodulin is a(n):

Accepted Answer

A) allosteric activator of calcium-dependent enzymes. 
B) allosteric inhibitor of calcium-dependent enzymes. 
C) calcium-dependent enzyme. 
D) cell surface calcium receptor. 
E) regulatory subunit of calcium-dependent enzymes. 
A) allosteric activator of calcium-dependent enzymes. 
B) allosteric inhibitor of calcium-dependent enzymes. 
C) calcium-dependent enzyme. 
D) cell surface calcium receptor. 
E) regulatory subunit of calcium-dependent enzymes.

Question 2

What is meant by multivalent adaptor proteins in signaling pathways?

Accepted Answer

The reversible phosphorylation (at Ser,T

Question 3

Protein kinase A (PKA)is:

Accepted Answer

A) activated by covalent binding of cyclic AMP. 
B) affected by cyclic AMP only under unusual circumstances. 
C) allosterically activated by cyclic AMP. 
D) competitively inhibited by cyclic AMP. 
E) noncompetitively inhibited by cyclic AMP. 
A) activated by covalent binding of cyclic AMP. 
B) affected by cyclic AMP only under unusual circumstances. 
C) allosterically activated by cyclic AMP. 
D) competitively inhibited by cyclic AMP. 
E) noncompetitively inhibited by cyclic AMP.

Question 4

The ion channel that opens in response to acetylcholine is an example of a ____________ signal transduction system.

Accepted Answer

A) G-protein 
B) ligand-gated 
C) receptor-enzyme 
D) serpentine receptor 
E) voltage-gated 
A) G-protein 
B) ligand-gated 
C) receptor-enzyme 
D) serpentine receptor 
E) voltage-gated

Question 5

Explain how mutations in the following proteins might result in either loss of responsiveness to a given hormone or production of a continuous signal even in the absence of the hormone: 
(a)a mutation in the regulatory (R)subunit of cAMP-dependent protein kinase,making R incapable of binding to the catalytic (C)subunit; 
(b)a mutation in a growth factor receptor with protein kinase activity; 
(c)a defect in a G protein that renders the GTPase activity inactive.

Accepted Answer

(a)When a mutation in the R subunit of c

Question 6

Steroid hormones are carried on specific carrier proteins because the hormones:

Accepted Answer

A) are too unstable to survive in the blood on their own. 
B) cannot dissolve readily in the blood because they are too hydrophobic. 
C) cannot find their target cells without them. 
D) need them in order to pass through the plasma membrane. 
E) require subsequent binding to specific receptor proteins in the nucleus. 
A) are too unstable to survive in the blood on their own. 
B) cannot dissolve readily in the blood because they are too hydrophobic. 
C) cannot find their target cells without them. 
D) need them in order to pass through the plasma membrane. 
E) require subsequent binding to specific receptor proteins in the nucleus.

Question 7

Explain how the cytokine erythropoetin activates transcription of specific genes essential in blood maturation.

Accepted Answer

Binding of erythropoetin to its plasma m

Question 8

Compare and contrast the modes of action of epinephrine,acting through the $\beta$-adrenergic receptor,and of insulin,acting through the insulin receptor.

Accepted Answer

[The mechanisms of epinephrine and insul

Question 9

What is the mechanism of action of the drug tamoxifen in the treatment of breast cancer?

Accepted Answer

Tamoxifen is an antagonist of estrogen,a

Question 10

Which of the following statements concerning signal transduction by the insulin receptor is not correct?

Accepted Answer

A) Activation of the receptor protein kinase activity results in the activation of additional protein kinases. 
B) Binding of insulin to the receptor activates a protein kinase. 
C) Binding of insulin to the receptor results in a change in its quaternary structure. 
D) The receptor protein kinase activity is specific for tyrosine residues on the substrate proteins. 
E) The substrates of the receptor protein kinase activity are mainly proteins that regulate transcription. 
A) Activation of the receptor protein kinase activity results in the activation of additional protein kinases. 
B) Binding of insulin to the receptor activates a protein kinase. 
C) Binding of insulin to the receptor results in a change in its quaternary structure. 
D) The receptor protein kinase activity is specific for tyrosine residues on the substrate proteins. 
E) The substrates of the receptor protein kinase activity are mainly proteins that regulate transcription.

Question 11

Compare and contrast ligand-gated and voltage-gated ion channels;give an example of each.

Accepted Answer

Ion channels are protein-based passages

Question 12

What is meant by the two-component system of bacterial cell signaling?

Accepted Answer

The two-component system drives bacteria

Question 13

Which of the following is not a shared feature of signaling by mammalian vision and gustatory receptor pathways?

Accepted Answer

A) Changes in cAMP levels 
B) GDP/GTP exchange 
C) Heterotrimeric G proteins 
D) Open/closing of ion channels 
E) Transmembrane receptors 
A) Changes in cAMP levels 
B) GDP/GTP exchange 
C) Heterotrimeric G proteins 
D) Open/closing of ion channels 
E) Transmembrane receptors

Question 14

Describe three factors that contribute to the high degree of sensitivity of signal transduction systems.

Accepted Answer

The sensitivity of signal transduction r

Question 15

Match the signal input with the result:
-

Accepted Answer

(a)-(2);

Question 16

Most transduction systems for hormones and sensory stimuli that involve trimeric G proteins have in common all of the following except:

Accepted Answer

A) cyclic nucleotides. 
B) nuclear receptors. 
C) receptors that interact with a G protein. 
D) receptors with multiple transmembrane segments. 
E) self-inactivation. 
A) cyclic nucleotides. 
B) nuclear receptors. 
C) receptors that interact with a G protein. 
D) receptors with multiple transmembrane segments. 
E) self-inactivation.

Question 17

Briefly compare the two types of guanylyl cyclases that participate in signal transduction.

Accepted Answer

One type is a membrane-bound homodimer w

Question 18

Describe two examples of steroid hormone action that occur too rapidly to be the consequence of altered levels of

Accepted Answer

Progesterone can cause a rapid decrease

Question 19

Which of the following is not a step in the response to photon absorption by rhodopsin?

Accepted Answer

A) Rhodopsin catalyzes GDP/GTP exchange on transducin. 
B) Rhodopsin is phosphorylated by rhodopsin kinase. 
C) Arrestin binds to the phosphorylated end of rhodopsin. 
D) Light absorption converts all-trans?-retinal to 11-cis-retinal. 
E) All-trans?-retinal is replaced with 11-cis-retinal. 
A) Rhodopsin catalyzes GDP/GTP exchange on transducin. 
B) Rhodopsin is phosphorylated by rhodopsin kinase. 
C) Arrestin binds to the phosphorylated end of rhodopsin. 
D) Light absorption converts all-trans?-retinal to 11-cis-retinal. 
E) All-trans?-retinal is replaced with 11-cis-retinal.

Question 20

Explain two different approaches to targeting the activity of aberrant protein kinases for treating cancer.Give examples of each.

Accepted Answer

One approach is to design small molecule

Exam 12: Biosignaling

Calmodulin is a(n):

What is meant by multivalent adaptor proteins in signaling pathways?

Protein kinase A (PKA)is:

The ion channel that opens in response to acetylcholine is an example of a ____________ signal transduction system.

Steroid hormones are carried on specific carrier proteins because the hormones:

Explain how the cytokine erythropoetin activates transcription of specific genes essential in blood maturation.

Compare and contrast the modes of action of epinephrine,acting through the β\betaβ -adrenergic receptor,and of insulin,acting through the insulin receptor.

What is the mechanism of action of the drug tamoxifen in the treatment of breast cancer?

Which of the following statements concerning signal transduction by the insulin receptor is not correct?

Compare and contrast ligand-gated and voltage-gated ion channels;give an example of each.

What is meant by the two-component system of bacterial cell signaling?

Which of the following is not a shared feature of signaling by mammalian vision and gustatory receptor pathways?

Describe three factors that contribute to the high degree of sensitivity of signal transduction systems.

Match the signal input with the result: -

Most transduction systems for hormones and sensory stimuli that involve trimeric G proteins have in common all of the following except:

Briefly compare the two types of guanylyl cyclases that participate in signal transduction.

Describe two examples of steroid hormone action that occur too rapidly to be the consequence of altered levels of

Which of the following is not a step in the response to photon absorption by rhodopsin?

Explain two different approaches to targeting the activity of aberrant protein kinases for treating cancer.Give examples of each.

The Foundations of Biochemistry

Water

Amino Acids, peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Principles of Bioenergetics

Glycolysis, gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, nucleotides, and Related Molecules

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Compare and contrast the modes of action of epinephrine,acting through the $\beta$ -adrenergic receptor,and of insulin,acting through the insulin receptor.