Question 1

What is an example of a lipid second messenger?

Accepted Answer

A)  Calcium 
B)  cAMP 
C)  cGMP 
D)  Diacylglycerol 
E)  Inositol phosphate 
A)  Calcium 
B)  cAMP 
C)  cGMP 
D)  Diacylglycerol 
E)  Inositol phosphate

Question 2

During signal transduction that involves heterotrimeric G proteins, the event that immediately precedes the dissociation to alpha monomer and beta-gamma dimer is the

Accepted Answer

A)  binding of a hormone ligand to the intact heterotrimer. 
B)  creation of new protein-protein interactions. 
C)  exchange of guanine nucleotides on the alpha subunit. 
D)  hydrolysis of guanosine triphosphate by the beta subunit. 
E)  posttranslational modification of the gamma subunit with a lipid anchor. 
A)  binding of a hormone ligand to the intact heterotrimer. 
B)  creation of new protein-protein interactions. 
C)  exchange of guanine nucleotides on the alpha subunit. 
D)  hydrolysis of guanosine triphosphate by the beta subunit. 
E)  posttranslational modification of the gamma subunit with a lipid anchor.

Question 3

Why are KD and EC50 usually not the same?

Accepted Answer

A)  Not all receptors are capable of activating cell response 
B)  Not all receptors are capable of binding ligand 
C)  Some receptors are inactive 
D)  Some receptors bind more than one ligand 
E)  The cell has "spare receptors" 
A)  Not all receptors are capable of activating cell response 
B)  Not all receptors are capable of binding ligand 
C)  Some receptors are inactive 
D)  Some receptors bind more than one ligand 
E)  The cell has "spare receptors"

Question 4

There are many types of proteins and protein domains that interact with signaling molecules. What domain interacts with inositol phospholipids?

Accepted Answer

A)  Phosphorylation site 
B)  Phosphotyrosine-binding site 
C)  Plekstrin homology 
D)  Src-homology type 2 
E)  Src-homology type 3 
A)  Phosphorylation site 
B)  Phosphotyrosine-binding site 
C)  Plekstrin homology 
D)  Src-homology type 2 
E)  Src-homology type 3

Question 5

As regards attenuation/control of the PI cycle second messengers, which of the following statements, if any, is/are true?

Accepted Answer

A)  Diacylglycerol (DAG) can be directly converted to Phosphatidic Acid. 
B)  Diacylglycerol (DAG) can also be converted to a fatty acid and a monoacylglycerol. 
C)  Upon ligand binding, GTP is exchanged for GDP on a monomeric G protein then hydrolysis of GTP to GDP will inactivate the G protein. 
D)  All of the above. 
E)  None of the above. 
A)  Diacylglycerol (DAG) can be directly converted to Phosphatidic Acid. 
B)  Diacylglycerol (DAG) can also be converted to a fatty acid and a monoacylglycerol. 
C)  Upon ligand binding, GTP is exchanged for GDP on a monomeric G protein then hydrolysis of GTP to GDP will inactivate the G protein. 
D)  All of the above. 
E)  None of the above.

Question 6

What characteristic is shared by molecules that signal via binding to intracellular receptors?

Accepted Answer

A)  Acidity 
B)  Aliphatic structure 
C)  Hydrophilicity 
D)  Hydrophobicity 
E)  Peptide nature 
A)  Acidity 
B)  Aliphatic structure 
C)  Hydrophilicity 
D)  Hydrophobicity 
E)  Peptide nature

Question 7

Which amino acid is modified when cholera toxin activates the G-protein cascade?

Accepted Answer

A)  Arginine in the a subunit 
B)  Glutamate in the adenyl cyclase 
C)  Histidine in protein kinase A 
D)  Lysine in the ab complex 
E)  Tyrosine in the receptor 
A)  Arginine in the a subunit 
B)  Glutamate in the adenyl cyclase 
C)  Histidine in protein kinase A 
D)  Lysine in the ab complex 
E)  Tyrosine in the receptor

Question 8

All of the following statements are true about cyclic AMP-dependent protein kinase EXCEPT which one?

Accepted Answer

A)  It is composed of a cyclic AMP binding protein dimer and 2 catalytic subunits. 
B)  It principally catalyzes the phosphorylation of tyrosine residues on proteins. 
C)  It catalyzes the conversion of inactive phosphorylase kinase to active phosphorylase kinase. 
D)  It activates hormone-sensitive lipase. 
E)  It inhibits glycogen synthase. 
A)  It is composed of a cyclic AMP binding protein dimer and 2 catalytic subunits. 
B)  It principally catalyzes the phosphorylation of tyrosine residues on proteins. 
C)  It catalyzes the conversion of inactive phosphorylase kinase to active phosphorylase kinase. 
D)  It activates hormone-sensitive lipase. 
E)  It inhibits glycogen synthase.

Question 9

Plasma membrane G protein? coupled receptors share which of these characteristics?

Accepted Answer

A)  catalytic activity for synthesis of a cyclic nucleoside monophosphate 
B)  covalent modification by ADP?ribosylation 
C)  identical primary sequences in the cytosolic domains 
D)  ligand binding site on the external surface 
E)  transmembrane core consisting of 10 alpha-helices. 
A)  catalytic activity for synthesis of a cyclic nucleoside monophosphate 
B)  covalent modification by ADP?ribosylation 
C)  identical primary sequences in the cytosolic domains 
D)  ligand binding site on the external surface 
E)  transmembrane core consisting of 10 alpha-helices.

Question 10

Which is a protein that can be translocated from cytosol to nucleus during cytokine-initiated signaling?

Accepted Answer

A)  Interferon 
B)  JAK 
C)  NFkB 
D)  SMAD 
E)  Src 
A)  Interferon 
B)  JAK 
C)  NFkB 
D)  SMAD 
E)  Src

Question 11

What type of signaling do prostaglandins use?

Accepted Answer

A)  Autocrine 
B)  Endocrine 
C)  Juxtacrine 
D)  Pilus 
E)  Synaptic 
A)  Autocrine 
B)  Endocrine 
C)  Juxtacrine 
D)  Pilus 
E)  Synaptic

Question 12

Some calmodulin kinases, such as CAM kinase II, remain active after calcium concentration has returned to the baseline. How is this achieved?

Accepted Answer

A)  Autophosphorylation 
B)  Calcium bind covalently to CAM 
C)  CAM associates with another activating ion 
D)  CAM binds to another protein 
E)  CAM is cleaved at the amino terminal 
A)  Autophosphorylation 
B)  Calcium bind covalently to CAM 
C)  CAM associates with another activating ion 
D)  CAM binds to another protein 
E)  CAM is cleaved at the amino terminal

Question 13

The role of phosphorylation of protein Tyr residues during signal transduction serves to

Accepted Answer

A)  deplete a pool of protein?bound Ca2+. 
B)  direct certain receptors to the endoplasmic reticulum. 
C)  promote specific interactions between proteins. 
D)  regulate the conversion of normal proteins to oncoproteins. 
E)  stimulate the synthesis of cyclic-AMP. 
A)  deplete a pool of protein?bound Ca2+. 
B)  direct certain receptors to the endoplasmic reticulum. 
C)  promote specific interactions between proteins. 
D)  regulate the conversion of normal proteins to oncoproteins. 
E)  stimulate the synthesis of cyclic-AMP.

Question 14

Where is intracellular calcium stored that can rapidly released when needed?

Accepted Answer

A)  Endoplasmic reticulum 
B)  Golgi 
C)  Lysosomes 
D)  Mitochondria 
E)  Nucleus 
A)  Endoplasmic reticulum 
B)  Golgi 
C)  Lysosomes 
D)  Mitochondria 
E)  Nucleus

Question 15

Certain bacterial exotoxins, such as cholera and pertussis, are useful in defining the steps and proteins in signal transduction pathways. Which of the following reactions best accounts for this toxin property?

Accepted Answer

A)  activation of specific lipid kinases 
B)  covalent modification of heterotrimeric G proteins 
C)  high?affinity binding to nuclear receptors 
D)  inhibition of cyclic nucleotide hydrolysis 
E)  rapid release of Ca2+ into cytosol 
A)  activation of specific lipid kinases 
B)  covalent modification of heterotrimeric G proteins 
C)  high?affinity binding to nuclear receptors 
D)  inhibition of cyclic nucleotide hydrolysis 
E)  rapid release of Ca2+ into cytosol

Question 16

What are the end products of arachidonic acid metabolism?

Accepted Answer

A)  Cyclic nucleotides 
B)  Cytokines 
C)  Eicosanoids 
D)  Lysolecithins 
E)  Steroid hormones 
A)  Cyclic nucleotides 
B)  Cytokines 
C)  Eicosanoids 
D)  Lysolecithins 
E)  Steroid hormones

Question 17

Which form of phosphatidylinositol phosphate is the precursor of IP3?

Accepted Answer

A)  Monophospho 
B)  Bisphospho 
C)  Trisphospho 
D)  Tetrakisphospho 
E)  Pentaphospho 
A)  Monophospho 
B)  Bisphospho 
C)  Trisphospho 
D)  Tetrakisphospho 
E)  Pentaphospho

Question 18

After a ligand-receptor complex enters a cell, how is the ligand disaggregated from the receptor so that the receptor can be reincorporated in the cell membrane?

Accepted Answer

A)  Alteration of lysosomal pH separates the molecules 
B)  Both return to membrane, and ligand is degraded extracellularly 
C)  Covalent binding of two ligands to each other 
D)  Degradation of receptor and ligand in the lysosome 
E)  Transfer to nucleus where ligand binds DNA 
A)  Alteration of lysosomal pH separates the molecules 
B)  Both return to membrane, and ligand is degraded extracellularly 
C)  Covalent binding of two ligands to each other 
D)  Degradation of receptor and ligand in the lysosome 
E)  Transfer to nucleus where ligand binds DNA

Question 19

In the hormonal activation of adenylate cyclase, and the subsequent formation of cyclic AMP, which of the following components is NOT necessary?

Accepted Answer

A)  hormone receptor 
B)  GTP 
C)  ATP 
D)  GDP 
E)  guanyl nucleotide regulatory protein 
A)  hormone receptor 
B)  GTP 
C)  ATP 
D)  GDP 
E)  guanyl nucleotide regulatory protein

Question 20

What class of compounds inhibit phosphodiesterases, thereby raising cAMP levels?

Accepted Answer

A)  Guanidinium 
B)  Indoles 
C)  Pyrimidines 
D)  Pyrroles 
E)  Xanthines 
A)  Guanidinium 
B)  Indoles 
C)  Pyrimidines 
D)  Pyrroles 
E)  Xanthines

Exam 13: Fundamentals of Signal Transduction

What is an example of a lipid second messenger?

During signal transduction that involves heterotrimeric G proteins, the event that immediately precedes the dissociation to alpha monomer and beta-gamma dimer is the

Why are KD and EC50 usually not the same?

There are many types of proteins and protein domains that interact with signaling molecules. What domain interacts with inositol phospholipids?

As regards attenuation/control of the PI cycle second messengers, which of the following statements, if any, is/are true?

What characteristic is shared by molecules that signal via binding to intracellular receptors?

Which amino acid is modified when cholera toxin activates the G-protein cascade?

All of the following statements are true about cyclic AMP-dependent protein kinase EXCEPT which one?

Plasma membrane G protein? coupled receptors share which of these characteristics?

Which is a protein that can be translocated from cytosol to nucleus during cytokine-initiated signaling?

What type of signaling do prostaglandins use?

Some calmodulin kinases, such as CAM kinase II, remain active after calcium concentration has returned to the baseline. How is this achieved?

The role of phosphorylation of protein Tyr residues during signal transduction serves to

Where is intracellular calcium stored that can rapidly released when needed?

Certain bacterial exotoxins, such as cholera and pertussis, are useful in defining the steps and proteins in signal transduction pathways. Which of the following reactions best accounts for this toxin property?

What are the end products of arachidonic acid metabolism?

Which form of phosphatidylinositol phosphate is the precursor of IP3?

After a ligand-receptor complex enters a cell, how is the ligand disaggregated from the receptor so that the receptor can be reincorporated in the cell membrane?

In the hormonal activation of adenylate cyclase, and the subsequent formation of cyclic AMP, which of the following components is NOT necessary?

What class of compounds inhibit phosphodiesterases, thereby raising cAMP levels?

Eukaryotic Cell Structure

DNA and RNA: Composition and Structure

Protein I: Composition and Structure

DNA Replication, Recombination, and Repair

RNA: Transcription and Rna Processing

Protein Synthesis: Translation and Posttranslational Modifications

Recombinant Dna and Biotechnology

Regulation of Gene Expression

Protein II: Structure-Function Relationships in Protein Families

Enzymes: Classification, Kinetics, and Control

The Cytochromes P450 and Nitric Oxide Synthases

Biological Membranes: Structure and Membrane Transport

Bioenergetics and Oxidative Metabolism

Carbohydrate Metabolism I: Major Metabolic Pathways and Their Control

Carbohydrate Metabolism II: Special Pathways and Glycoconjugates

Lipid Metabolism I: Synthesis, Storage, and Utilization of Fatty Acids and Triacylglycerols

Lipid Metabolism II: Pathways of Metabolism of Special Lipids

Amino Acid Metabolism

Purine and Pyrimidine Nucleotide Metabolism

Metabolic Interrelationships

Biochemistry of Hormones

Molecular Cell Biology

Cell Cycle, Programmed Cell Death, and Cancer

Digestion and Absorption of Basic Nutritional Constituents

Digestion and Absorption of Basic Nutritional Constituents

Principles of Nutrition I and II

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Why are K_Dand EC₅₀usually not the same?