Question 1

What is cell-cell signaling that requires the cells to be in contact called?

Accepted Answer

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

Question 2

Extracellular calcium has approximately the same concentration as the intra-organelle-stored calcium. Approximately what is this concentration?

Accepted Answer

A)  10-1 M 
B)  10-3 M 
C)  10-6 M 
D)  10-9 M 
E)  10-12 M 
A)  10-1 M 
B)  10-3 M 
C)  10-6 M 
D)  10-9 M 
E)  10-12 M

Question 3

As regards receptors coupled to Gs (G-stimulatory) and cAMP, which of the following is false?

Accepted Answer

A)  Binding of ligand to its receptor activates another distinct protein which catalyzes the displacement of GDP with GTP on the alpha Gs subunit. 
B)  The GTP?Gs alpha subunit dissociates from the beta/gamma subunits and activates adenylate cyclase. 
C)  Adenylate cyclase catalyzes the conversion of ATP to cAMP. 
D)  cAMP activates cAMP dependent protein kinase by binding to the regulatory subunits which causes dissociation of the regulatory subunits from the catalytic subunits. 
E)  The catalytic subunit of cAMP dependent protein kinase can phosphorylate proteins on serine. 
A)  Binding of ligand to its receptor activates another distinct protein which catalyzes the displacement of GDP with GTP on the alpha Gs subunit. 
B)  The GTP?Gs alpha subunit dissociates from the beta/gamma subunits and activates adenylate cyclase. 
C)  Adenylate cyclase catalyzes the conversion of ATP to cAMP. 
D)  cAMP activates cAMP dependent protein kinase by binding to the regulatory subunits which causes dissociation of the regulatory subunits from the catalytic subunits. 
E)  The catalytic subunit of cAMP dependent protein kinase can phosphorylate proteins on serine.

Question 4

Acetylcholine can work as a ligand-gated ion channel receptor in skeletal muscle. How does it work in the heart?

Accepted Answer

A)  As a ligand-gated channel 
B)  By a juxtacrine mechanism 
C)  By promoting release of cytokines 
D)  Via a G-protein-linked receptor 
E)  Via an enzyme-linked receptor 
A)  As a ligand-gated channel 
B)  By a juxtacrine mechanism 
C)  By promoting release of cytokines 
D)  Via a G-protein-linked receptor 
E)  Via an enzyme-linked receptor

Question 5

How many of the 14 domains described for adenyl cyclase span the membrane?

Accepted Answer

A)  5 
B)  7 
C)  9 
D)  12 
E)  14 
A)  5 
B)  7 
C)  9 
D)  12 
E)  14

Question 6

To what type of receptor do most neurotransmitters bind on the post-synaptic membrane?

Accepted Answer

A)  Adenyl cyclase-associated 
B)  Autophosphorylating 
C)  Ion channel 
D)  PKC-associated 
E)  Voltage-gated channel 
A)  Adenyl cyclase-associated 
B)  Autophosphorylating 
C)  Ion channel 
D)  PKC-associated 
E)  Voltage-gated channel

Question 7

In what way do cytokine receptors differ from receptor tyrosine kinases?

Accepted Answer

A)  The carboxyl end is intracellular 
B)  They are associated with a G-protein 
C)  They are made of several transmembrane helices 
D)  They do not span the membrane 
E)  They have no inherent enzyme activity 
A)  The carboxyl end is intracellular 
B)  They are associated with a G-protein 
C)  They are made of several transmembrane helices 
D)  They do not span the membrane 
E)  They have no inherent enzyme activity

Question 8

An intracellular signal transducing ion for many hormones is

Accepted Answer

A)  bicarbonate. 
B)  calcium. 
C)  chloride. 
D)  magnesium. 
E)  phosphate. 
A)  bicarbonate. 
B)  calcium. 
C)  chloride. 
D)  magnesium. 
E)  phosphate.

Question 9

In the figure above which letter represents EC50?

Accepted Answer

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

Question 10

5Inositol 1,4,5-trisphosphate (IP3)

Accepted Answer

A)  is a long-lived messenger of hormone action. 
B)  causes the rapid release of calcium from intracellular stores. 
C)  is a product of a protein kinase C reaction. 
D)  cannot undergo further phosphorylation. 
E)  is essential for the action of calmodulin. 
A)  is a long-lived messenger of hormone action. 
B)  causes the rapid release of calcium from intracellular stores. 
C)  is a product of a protein kinase C reaction. 
D)  cannot undergo further phosphorylation. 
E)  is essential for the action of calmodulin.

Question 11

The compound transferred to a protein by cholera toxin is

Accepted Answer

A)  ADP 
B)  NAD+ 
C)  ADPribose 
D)  GMP 
E)  NADP+ 
A)  ADP 
B)  NAD+ 
C)  ADPribose 
D)  GMP 
E)  NADP+

Question 12

How does protein kinase A effect responses at the level of transcription?

Accepted Answer

A)  It binds a cAMP-sensitive regulatory element (CR
E)  
B)  It phosphorylates CREBs (cAMP-regulated gene regulatory proteins) 
C)  PKA phosphorylates a small molecule that enters the nucleus and binds CRE 
D)  The regulatory subunits deactivate repressors 
E)  The regulatory subunits of the enzyme enter the nucleus and bind DNA 
A)  It binds a cAMP-sensitive regulatory element (CR
E)  
B)  It phosphorylates CREBs (cAMP-regulated gene regulatory proteins) 
C)  PKA phosphorylates a small molecule that enters the nucleus and binds CRE 
D)  The regulatory subunits deactivate repressors 
E)  The regulatory subunits of the enzyme enter the nucleus and bind DNA

Question 13

Atrial natriuretic factor (ANF) stimulates guanylate cyclase in vascular smooth muscle and kidney. Where is ANF synthesized?

Accepted Answer

A)  Adrenals 
B)  Heart 
C)  Intestines 
D)  Liver 
E)  Lung 
A)  Adrenals 
B)  Heart 
C)  Intestines 
D)  Liver 
E)  Lung

Question 14

What type of modification is promoted on G-proteins by cholera toxin?

Accepted Answer

A)  ADP-ribosylation 
B)  Deamination 
C)  N-acetylation 
D)  Phosphorylation 
E)  Sulfhydryl hydrolysis 
A)  ADP-ribosylation 
B)  Deamination 
C)  N-acetylation 
D)  Phosphorylation 
E)  Sulfhydryl hydrolysis

Question 15

As regards receptor? mediated hydrolysis of phosphatidylinositol, which of the following statements, if any, is/are true?

Accepted Answer

A)  Activated Protein Kinase C activates the transcription factor NF Kappa B by directly phosphorylating it which allows its release from I Kappa B (the cytosolic inhibitor). 
B)  Protein Kinase C activity is directly stimulated by calcium and IP3. 
C)  In receptors coupled to the PI cycle but not containing an intrinsic tyrosine kinase activity, the two second messengers of the PI cycle are released by the enzyme phospholipase C Gamma?l 
D)  All of the above. 
E)  None of the above. 
A)  Activated Protein Kinase C activates the transcription factor NF Kappa B by directly phosphorylating it which allows its release from I Kappa B (the cytosolic inhibitor). 
B)  Protein Kinase C activity is directly stimulated by calcium and IP3. 
C)  In receptors coupled to the PI cycle but not containing an intrinsic tyrosine kinase activity, the two second messengers of the PI cycle are released by the enzyme phospholipase C Gamma?l 
D)  All of the above. 
E)  None of the above.

Question 16

Which of the following is NOT an intracellular mediator (second messenger) of hormone action?

Accepted Answer

A)  G protein 
B)  cAMP 
C)  calmodulin 
D)  diacylglycerol (DG) 
E)  inositol triphosphate (IP3) 
A)  G protein 
B)  cAMP 
C)  calmodulin 
D)  diacylglycerol (DG) 
E)  inositol triphosphate (IP3)

Question 17

Cyclic AMP can activate the synthesis of some enzymes. It is likely that the mechanism involves

Accepted Answer

A)  binding of free cAMP to a nucleotide sequence in the promoter region of the gene for the enzyme. 
B)  phosphorylation of an acidic protein which is bound to the gene for the enzyme. 
C)  phosphorylation of a glucocorticoid receptor protein which then migrates to the nucleus and activates the gene for the enzyme. 
D)  binding of cAMP to a protein kinase regulatory subunit which migrates to the nucleus, binds to chromatin, and activates the gene for the protein. 
E)  phosphorylation of initiation factor IF-2 which stimulates translation of the mRNA for the enzymes. 
A)  binding of free cAMP to a nucleotide sequence in the promoter region of the gene for the enzyme. 
B)  phosphorylation of an acidic protein which is bound to the gene for the enzyme. 
C)  phosphorylation of a glucocorticoid receptor protein which then migrates to the nucleus and activates the gene for the enzyme. 
D)  binding of cAMP to a protein kinase regulatory subunit which migrates to the nucleus, binds to chromatin, and activates the gene for the protein. 
E)  phosphorylation of initiation factor IF-2 which stimulates translation of the mRNA for the enzymes.

Question 18

Which of the following is a TRUE statement?

Accepted Answer

A)  All protein kinases are activated by cyclic AMP. 
B)  The subunit of the protein kinase that binds cyclic AMP is the catalytic subunit. 
C)  Caffeine increases the rate of cyclic AMP degradation. 
D)  Hormones activate adenylate cyclase by binding directly to the adenylate cyclase molecule. 
E)  The enzyme that inactivates cyclic AMP is a phosphodiesterase. 
A)  All protein kinases are activated by cyclic AMP. 
B)  The subunit of the protein kinase that binds cyclic AMP is the catalytic subunit. 
C)  Caffeine increases the rate of cyclic AMP degradation. 
D)  Hormones activate adenylate cyclase by binding directly to the adenylate cyclase molecule. 
E)  The enzyme that inactivates cyclic AMP is a phosphodiesterase.

Exam 13: Fundamentals of Signal Transduction

What is cell-cell signaling that requires the cells to be in contact called?

Extracellular calcium has approximately the same concentration as the intra-organelle-stored calcium. Approximately what is this concentration?

As regards receptors coupled to Gs (G-stimulatory) and cAMP, which of the following is false?

Acetylcholine can work as a ligand-gated ion channel receptor in skeletal muscle. How does it work in the heart?

How many of the 14 domains described for adenyl cyclase span the membrane?

To what type of receptor do most neurotransmitters bind on the post-synaptic membrane?

In what way do cytokine receptors differ from receptor tyrosine kinases?

An intracellular signal transducing ion for many hormones is

In the figure above which letter represents EC50?

5Inositol 1,4,5-trisphosphate (IP3)

The compound transferred to a protein by cholera toxin is

How does protein kinase A effect responses at the level of transcription?

Atrial natriuretic factor (ANF) stimulates guanylate cyclase in vascular smooth muscle and kidney. Where is ANF synthesized?

What type of modification is promoted on G-proteins by cholera toxin?

As regards receptor? mediated hydrolysis of phosphatidylinositol, which of the following statements, if any, is/are true?

Which of the following is NOT an intracellular mediator (second messenger) of hormone action?

Cyclic AMP can activate the synthesis of some enzymes. It is likely that the mechanism involves

Which of the following is a TRUE statement?

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

Filters

In the figure above which letter represents EC₅₀?