Question 1

What is expected to happen when epinephrine binds to its receptor in a myocyte?

Accepted Answer

A)  Intracellular cAMP levels will rise. 
B)  Glycogen synthase will become active. 
C)  Glycogen phosphorylase will be phosphorylated. 
D)  Intracellular cAMP levels will rise, and glycogen phosphorylase will be phosphorylated. 
E)  Glycogen synthase will become active, and glycogen phosphorylase will be phosphorylated. 
A)  Intracellular cAMP levels will rise. 
B)  Glycogen synthase will become active. 
C)  Glycogen phosphorylase will be phosphorylated. 
D)  Intracellular cAMP levels will rise, and glycogen phosphorylase will be phosphorylated. 
E)  Glycogen synthase will become active, and glycogen phosphorylase will be phosphorylated.

Question 2

Phosphorylation of a tyrosine in the cyclin-dependent kinases (CDK) inactivates the protein by:

Accepted Answer

A)  inhibiting the binding of cyclin. 
B)  inhibiting the binding of ATP. 
C)  inhibiting the binding of the "T loop." 
D)  preventing dissociation of the CDK/cyclin complex. 
A)  inhibiting the binding of cyclin. 
B)  inhibiting the binding of ATP. 
C)  inhibiting the binding of the "T loop." 
D)  preventing dissociation of the CDK/cyclin complex.

Question 3

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) A mutation in the regulatory (R) sub

Question 4

Which factor is NOT involved in the specificity of signal transduction?

Accepted Answer

A)  interactions between receptor and signal molecules 
B)  location of receptor molecules 
C)  structure of receptor molecules 
D)  structure of signal molecules 
E)  transmembrane transport of signal molecules by receptor molecules 
A)  interactions between receptor and signal molecules 
B)  location of receptor molecules 
C)  structure of receptor molecules 
D)  structure of signal molecules 
E)  transmembrane transport of signal molecules by receptor molecules

Question 5

Briefly explain the difference between nitric oxide (NO)-dependent cGMP synthesis and atrial natriuretic factor (ANF)-dependent cGMP synthesis.

Accepted Answer

Nitric oxide (NO)-dependent cGMP synthes

Question 6

How do ligand-gated ion channels play a role in sensory transduction in the eye?

Accepted Answer

Ligand-gated ion channels play a crucial

Question 7

Describe the relationship between a proto-oncogene and an oncogene, and explain how one arises from the other.

Accepted Answer

A proto-oncogene is a normal gene that h

Question 8

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

Accepted Answer

Tamoxifen is a selective estrogen recept

Question 9

Proto-oncogenes CANNOT be transformed to oncogenes by:

Accepted Answer

A)  chemically induced mutagenesis. 
B)  chromosomal rearrangements. 
C)  during a viral infection cycle. 
D)  elimination of their start signals for translation. 
E)  radiation-induced mutation. 
A)  chemically induced mutagenesis. 
B)  chromosomal rearrangements. 
C)  during a viral infection cycle. 
D)  elimination of their start signals for translation. 
E)  radiation-induced mutation.

Question 10

Which item is NOT one of the general types of signaling mechanisms found in multicellular organisms?

Accepted Answer

A)  gated ion channels 
B)  receptor tyrosine kinases 
C)  G protein-coupled receptors 
D)  receptor cAMP cyclases 
E)  adhesion receptors 
A)  gated ion channels 
B)  receptor tyrosine kinases 
C)  G protein-coupled receptors 
D)  receptor cAMP cyclases 
E)  adhesion receptors

Question 11

Which feature of signal-transduction comes from high structural and chemical complementarity between a signal molecule and its receptor?

Accepted Answer

A)  specificity 
B)  cooperativity 
C)  amplification 
D)  desensitization 
E)  integration 
A)  specificity 
B)  cooperativity 
C)  amplification 
D)  desensitization 
E)  integration

Question 12

Describe the sequence of biochemical events between the release of epinephrine into the bloodstream and the activation of the enzyme glycogen phosphorylase.

Accepted Answer

When epinephrine is released into the bl

Question 13

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

Accepted Answer

Erythropoietin is a cytokine that plays

Question 14

Which gated ion channel is associated with membrane repolarization in neurons?

Accepted Answer

A)  Na+ channel 
B)  K+ channel 
C)  Ca2+ channel 
D)  acetylcholine receptor ion channel 
E)  both Na+ and Ca2+ channels 
A)  Na+ channel 
B)  K+ channel 
C)  Ca2+ channel 
D)  acetylcholine receptor ion channel 
E)  both Na+ and Ca2+ channels

Question 15

Cyclin-dependent protein kinases can regulate the progression of cells through the cell cycle by phosphorylation of proteins such as:

Accepted Answer

A)  insulin. 
B)  myoglobin. 
C)  myosin. 
D)  retinal rod and cone proteins. 
E)  All of the answers are correct. 
A)  insulin. 
B)  myoglobin. 
C)  myosin. 
D)  retinal rod and cone proteins. 
E)  All of the answers are correct.

Question 16

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

Accepted Answer

Ligand-gated ion channels and voltage-ga

Question 17

Which statement is NOT true for G protein-coupled receptors (GPCRs)?

Accepted Answer

A)  Agonists mimic the effect of the natural ligand. 
B)  Antagonists block the normal effect of the natural ligand. 
C)  GPCRs interact with heterodimeric G proteins. 
D)  GPCRs are have seven transmembrane helices. 
E)  There exist >100 orphan GPCRs in the human genome with no known ligand. 
A)  Agonists mimic the effect of the natural ligand. 
B)  Antagonists block the normal effect of the natural ligand. 
C)  GPCRs interact with heterodimeric G proteins. 
D)  GPCRs are have seven transmembrane helices. 
E)  There exist >100 orphan GPCRs in the human genome with no known ligand.

Question 18

GTP binding to which subunit in a heterotrimeric G-protein is associated with a receptor signal?

Accepted Answer

A)  the $\alpha$ subunit 
B)  the $\beta$ subunit 
C)  the$\gamma$ subunit 
D)  a $\beta$/$\gamma$ dimer 
E)  None of the answers is correct. 
A)  the $\alpha$ subunit 
B)  the $\beta$ subunit 
C)  the$\gamma$ subunit 
D)  a $\beta$/$\gamma$ dimer 
E)  None of the answers is correct.

Question 19

Briefly describe the ethylene detection system of plants.

Accepted Answer

Plants have evolved a sophisticated ethy

Question 20

Which process acts through a G protein-coupled receptor?

Accepted Answer

A)  $\beta$-adrenergic response 
B)  light detection by rhodopsin 
C)  insulin-dependent activation of protein kinase B 
D)  both $\beta$-adrenergic response and light detection by rhodopsin 
E)  both light detection by rhodopsin and insulin-dependent activation of protein kinase B 
A)  $\beta$-adrenergic response 
B)  light detection by rhodopsin 
C)  insulin-dependent activation of protein kinase B 
D)  both $\beta$-adrenergic response and light detection by rhodopsin 
E)  both light detection by rhodopsin and insulin-dependent activation of protein kinase B

Exam 12: Biosignaling

What is expected to happen when epinephrine binds to its receptor in a myocyte?

Phosphorylation of a tyrosine in the cyclin-dependent kinases (CDK) inactivates the protein by:

Which factor is NOT involved in the specificity of signal transduction?

Briefly explain the difference between nitric oxide (NO)-dependent cGMP synthesis and atrial natriuretic factor (ANF)-dependent cGMP synthesis.

How do ligand-gated ion channels play a role in sensory transduction in the eye?

Describe the relationship between a proto-oncogene and an oncogene, and explain how one arises from the other.

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

Proto-oncogenes CANNOT be transformed to oncogenes by:

Which item is NOT one of the general types of signaling mechanisms found in multicellular organisms?

Which feature of signal-transduction comes from high structural and chemical complementarity between a signal molecule and its receptor?

Describe the sequence of biochemical events between the release of epinephrine into the bloodstream and the activation of the enzyme glycogen phosphorylase.

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

Which gated ion channel is associated with membrane repolarization in neurons?

Cyclin-dependent protein kinases can regulate the progression of cells through the cell cycle by phosphorylation of proteins such as:

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

Which statement is NOT true for G protein-coupled receptors (GPCRs)?

GTP binding to which subunit in a heterotrimeric G-protein is associated with a receptor signal?

Briefly describe the ethylene detection system of plants.

Which process acts through a G protein-coupled receptor?

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

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Bioenergetics and Biochemical Reaction Types

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

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

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