Question 1

Regulation of metabolism by activation of the gene encoding a particular enzyme is called ____.

Accepted Answer

A)  covalent modification 
B)  repression 
C)  induction 
D)  allosteric activation 
E)  none of the above 
A)  covalent modification 
B)  repression 
C)  induction 
D)  allosteric activation 
E)  none of the above C

Question 2

All are properties of regulatory enzymes EXCEPT:

Accepted Answer

A)  pathway end-products may act as allosteric inhibitors. 
B)  v vs [S] plots are sigmoid- or S-shaped. 
C)  substrate binding is cooperative. 
D)  monomeric enzymes with a single regulated active site. 
E)  may be stimulated by allosteric activators. 
A)  pathway end-products may act as allosteric inhibitors. 
B)  v vs [S] plots are sigmoid- or S-shaped. 
C)  substrate binding is cooperative. 
D)  monomeric enzymes with a single regulated active site. 
E)  may be stimulated by allosteric activators. D

Question 3

Of the following, which promotes the release of oxygen by hemoglobin?

Accepted Answer

A)  increase in [H+] 
B)  decrease in [CO2] 
C)  decrease in [2,3-bisphosphoglycerate] 
D)  Tyr HC2-Val FG5 hydrogen bond breaking 
E)  none of the above 
A)  increase in [H+] 
B)  decrease in [CO2] 
C)  decrease in [2,3-bisphosphoglycerate] 
D)  Tyr HC2-Val FG5 hydrogen bond breaking 
E)  none of the above A

Question 4

Discuss zymogens.​

Accepted Answer

Some proteins are synthesized as inactiv

Question 5

Which statement below about contrasting Hb and Mb is FALSE?

Accepted Answer

A)  Hb shows sigmoidal, whereas Mb shows hyperbolic oxygen saturation curves. 
B)  Hb shows cooperativity, whereas Mb does not. 
C)  Hb binds O2 more tightly than Mb. 
D)  Oxygen binds to a ferrous ion in both proteins. 
E)  Hb-oxygen binding is dependent on physiological changes in pH, whereas Mb-oxygen binding is not. 
A)  Hb shows sigmoidal, whereas Mb shows hyperbolic oxygen saturation curves. 
B)  Hb shows cooperativity, whereas Mb does not. 
C)  Hb binds O2 more tightly than Mb. 
D)  Oxygen binds to a ferrous ion in both proteins. 
E)  Hb-oxygen binding is dependent on physiological changes in pH, whereas Mb-oxygen binding is not.

Question 6

All of the following are correct statements about enzyme regulation EXCEPT:

Accepted Answer

A)  Enzymes can be inhibited by the products they produce. 
B)  Enzymes can be inactivated by the addition of a functional group. 
C)  Coenzyme and substrate availability can regulate enzyme reaction rate. 
D)  The reaction rate slows as equilibrium is approached. 
E)  The activity of an enzyme is covalently affected by allosteric regulators. 
A)  Enzymes can be inhibited by the products they produce. 
B)  Enzymes can be inactivated by the addition of a functional group. 
C)  Coenzyme and substrate availability can regulate enzyme reaction rate. 
D)  The reaction rate slows as equilibrium is approached. 
E)  The activity of an enzyme is covalently affected by allosteric regulators.

Question 7

Glycogen phosphorylase displays allosteric activation and inhibition by multiple modes. Which of the following is a correct relation?

Accepted Answer

A)  phosphate: positive heterotropic effector 
B)  AMP: negative heterotropic effector 
C)  ATP: positive heterotropic effector 
D)  glucose-6-phosphate: negative heterotropic effector 
E)  phosphorylation: covalent inhibitor 
A)  phosphate: positive heterotropic effector 
B)  AMP: negative heterotropic effector 
C)  ATP: positive heterotropic effector 
D)  glucose-6-phosphate: negative heterotropic effector 
E)  phosphorylation: covalent inhibitor

Question 8

The correct sequence for the hormone-activated enzymatic cascade that leads to activation of glycogen phosphorylase is:
A.Phosphorylation to activate phosphorylase kinase
B.Activation of G-protein
C.Activation of adenylyl cyclase to produce cAMP
D.Phosphorylation of glycogen phosphorylase
E.cAMP activation of protein kinase A (PKA)

Accepted Answer

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

Question 9

The cause of cell sickling in sickle cell anemia is:

Accepted Answer

A)  interaction of oxy-Hb S with the cell membrane. 
B)  precipitation of deoxy-Hb S into long, chain-like fibers. 
C)  formation of oxy-Hb S complexes and subsequent cell disruption. 
D)  precipitation of Hb S - Hb A hybrid molecules. 
E)  none of the above. 
A)  interaction of oxy-Hb S with the cell membrane. 
B)  precipitation of deoxy-Hb S into long, chain-like fibers. 
C)  formation of oxy-Hb S complexes and subsequent cell disruption. 
D)  precipitation of Hb S - Hb A hybrid molecules. 
E)  none of the above.

Question 10

Discuss acetylation as a prominent modification for the regulation of metabolic enzymes.​

Accepted Answer

Reversible acetylation/deacetylation of

Question 11

Which of the following is true regarding effectors of oxygen-hemoglobin binding?

Accepted Answer

A)  actively metabolizing tissues produce acid which increases hemoglobin's affinity for oxygen 
B)  the presence of CO2 enhances the release of oxygen from hemoglobin 
C)  2,3-bisphosphoglycerate must dissociate from hemoglobin before oxygen can be released 
D)  the presence of protons will counter the effect of CO2 on the realease of oxygen by hemoglobin 
E)  none of the above 
A)  actively metabolizing tissues produce acid which increases hemoglobin's affinity for oxygen 
B)  the presence of CO2 enhances the release of oxygen from hemoglobin 
C)  2,3-bisphosphoglycerate must dissociate from hemoglobin before oxygen can be released 
D)  the presence of protons will counter the effect of CO2 on the realease of oxygen by hemoglobin 
E)  none of the above

Question 12

All are true for cAMP-dependent protein kinase EXCEPT:

Accepted Answer

A)  also known as PKA. 
B)  phosphorylase kinase is a substrate. 
C)  consists of a pair of catalytic subunits. 
D)  two regulatory subunits block catalytic activity without cAMP binding. 
E)  phosphorylates glycogen phosphorylase. 
A)  also known as PKA. 
B)  phosphorylase kinase is a substrate. 
C)  consists of a pair of catalytic subunits. 
D)  two regulatory subunits block catalytic activity without cAMP binding. 
E)  phosphorylates glycogen phosphorylase.

Question 13

Usually the quickest method of influencing an enzymatic activity is by:

Accepted Answer

A)  allosteric regulation. 
B)  covalent modification. 
C)  enzyme induction. 
D)  activation of a zymogen. 
E)  enzyme destruction. 
A)  allosteric regulation. 
B)  covalent modification. 
C)  enzyme induction. 
D)  activation of a zymogen. 
E)  enzyme destruction.

Question 14

All are characteristic of allosteric enzymes EXCEPT:

Accepted Answer

A)  Effectors may show stimulatory or inhibitory activity. 
B)  They have multiple subunits. 
C)  They obey Michaelis-Menten kinetics. 
D)  The regulatory effect is by altering conformation and interaction of subunits. 
E)  Binding one subunit impacts binding of substrate to other subunits. 
A)  Effectors may show stimulatory or inhibitory activity. 
B)  They have multiple subunits. 
C)  They obey Michaelis-Menten kinetics. 
D)  The regulatory effect is by altering conformation and interaction of subunits. 
E)  Binding one subunit impacts binding of substrate to other subunits.

Question 15

Characteristics of glycogen phosphorylase include all EXCEPT:

Accepted Answer

A)  covalently linked pyridoxal phosphate. 
B)  an active site at the center of each of two identical subunits. 
C)  regulatory phosphorylation site on a Ser residue. 
D)  allosteric effector sites for ATP and glucose-6-phosphate. 
E)  all are true. 
A)  covalently linked pyridoxal phosphate. 
B)  an active site at the center of each of two identical subunits. 
C)  regulatory phosphorylation site on a Ser residue. 
D)  allosteric effector sites for ATP and glucose-6-phosphate. 
E)  all are true.

Question 16

Which of the following statements is correct regarding isozymes?

Accepted Answer

A)  they catalyze the same reaction but have vastly different structures 
B)  they are always monomeric proteins 
C)  their differences are based upon the type of tissue in which they are present 
D)  they often respond to different inhibitors and activators 
E)  both c and d are correct 
A)  they catalyze the same reaction but have vastly different structures 
B)  they are always monomeric proteins 
C)  their differences are based upon the type of tissue in which they are present 
D)  they often respond to different inhibitors and activators 
E)  both c and d are correct

Question 17

Glycogen phosphorylase displays allosteric activation and inhibition by multiple modes. Which of the following is a correct relation?

Accepted Answer

A)  phosphate: positive heterotropic effector 
B)  AMP: negative heterotropic effector 
C)  ATP: positive heterotropic effector 
D)  glucose-6-phosphate: negative heterotropic effector 
E)  phosphorylation: covalent inhibitor 
A)  phosphate: positive heterotropic effector 
B)  AMP: negative heterotropic effector 
C)  ATP: positive heterotropic effector 
D)  glucose-6-phosphate: negative heterotropic effector 
E)  phosphorylation: covalent inhibitor

Question 18

The T form (tense or taut form) of deoxyhemoglobin differs from oxyhemoglobin (the R form or relaxed form) by all EXCEPT:

Accepted Answer

A)  covalent linkages between subunits. 
B)  specific intrachain hydrogen bonds. 
C)  between β-subunit salt links (ion-pair bonds). 
D)  between α-subunits salt links (ion-pair bonds). 
E)  intrachain salt bridges. 
A)  covalent linkages between subunits. 
B)  specific intrachain hydrogen bonds. 
C)  between β-subunit salt links (ion-pair bonds). 
D)  between α-subunits salt links (ion-pair bonds). 
E)  intrachain salt bridges.

Question 19

Proinsulin is converted into insulin by:

Accepted Answer

A)  proteolytic excision of a specific peptide. 
B)  allosteric binding of glucose. 
C)  phosphorylation to the active form. 
D)  removal of phosphate by converter enzymes. 
E)  none of the above. 
A)  proteolytic excision of a specific peptide. 
B)  allosteric binding of glucose. 
C)  phosphorylation to the active form. 
D)  removal of phosphate by converter enzymes. 
E)  none of the above.

Question 20

Adenylyl cyclase catalyzes the synthesis of cAMP, and cAMP hydrolysis is catalyzed by a 5'-phosphodiesterase. If caffeine inhibits 5'-phosphodiesterases, drinking a caffeinated beverage would ____ cAMP levels and ____ glycogen phosphorylase activity.

Accepted Answer

A)  increase; decrease 
B)  increase; increase 
C)  decrease; decrease 
D)  decrease; increase 
E)  have no effect; have no effect 
A)  increase; decrease 
B)  increase; increase 
C)  decrease; decrease 
D)  decrease; increase 
E)  have no effect; have no effect

Exam 15: Enzyme Regulation

Regulation of metabolism by activation of the gene encoding a particular enzyme is called ____.

All are properties of regulatory enzymes EXCEPT:

Of the following, which promotes the release of oxygen by hemoglobin?

Discuss zymogens.​

Which statement below about contrasting Hb and Mb is FALSE?

All of the following are correct statements about enzyme regulation EXCEPT:

Glycogen phosphorylase displays allosteric activation and inhibition by multiple modes. Which of the following is a correct relation?

The cause of cell sickling in sickle cell anemia is:

Discuss acetylation as a prominent modification for the regulation of metabolic enzymes.​

Which of the following is true regarding effectors of oxygen-hemoglobin binding?

All are true for cAMP-dependent protein kinase EXCEPT:

Usually the quickest method of influencing an enzymatic activity is by:

All are characteristic of allosteric enzymes EXCEPT:

Characteristics of glycogen phosphorylase include all EXCEPT:

Which of the following statements is correct regarding isozymes?

Glycogen phosphorylase displays allosteric activation and inhibition by multiple modes. Which of the following is a correct relation?

The T form (tense or taut form) of deoxyhemoglobin differs from oxyhemoglobin (the R form or relaxed form) by all EXCEPT:

Proinsulin is converted into insulin by:

Adenylyl cyclase catalyzes the synthesis of cAMP, and cAMP hydrolysis is catalyzed by a 5'-phosphodiesterase. If caffeine inhibits 5'-phosphodiesterases, drinking a caffeinated beverage would ____ cAMP levels and ____ glycogen phosphorylase activity.

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids and the Peptide Bond

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, Tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Membranes and Membrane Transport

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Recombinant Dna, Cloning, Chimeric Genes, and Synthetic Biology

Enzymeskinetics and Specificity

Mechanisms of Enzyme Action

Molecular Motors

Metabolism: an Overview

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Lipid Biosynthesis

Nitrogen Acquisition and Amino Acid Metabolism

Synthesis and Degradation of Nucleotides

Metabolic Integration and Organ Specialization

Dna Metabolism: Replication, Recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

Completing the Protein Life Cycle: Folding, Processing, and Degradation

The Reception and Transmission of Extracellular Information

Filters

Discuss zymogens.

Discuss acetylation as a prominent modification for the regulation of metabolic enzymes.

Adenylyl cyclase catalyzes the synthesis of cAMP, and cAMP hydrolysis is catalyzed by a 5'-phosphodiesterase. If caffeine inhibits 5'-phosphodiesterases, drinking a caffeinated beverage would cAMP levels and glycogen phosphorylase activity.