Question 1

We are protected to some extent against low level CO poisoning because:

Accepted Answer

A)  His F8 on Hb distorts the heme iron atom out of the heme plane and attracts O2, but not CO. 
B)  Affinity of Hb for O2 is much greater than for CO. 
C)  His E7 blocks perpendicular binding of CO to heme iron allowing for better binding competition by O2. 
D)  The competition of O2 for heme is much greater than CO for heme. 
E)  None of the above. 
A)  His F8 on Hb distorts the heme iron atom out of the heme plane and attracts O2, but not CO. 
B)  Affinity of Hb for O2 is much greater than for CO. 
C)  His E7 blocks perpendicular binding of CO to heme iron allowing for better binding competition by O2. 
D)  The competition of O2 for heme is much greater than CO for heme. 
E)  None of the above.

Question 2

The presence of a negative allosteric effector on an allosteric protein would:

Accepted Answer

A)  cause a shift to the left in the sigmoidal curve. 
B)  increase the number of R conformations. 
C)  decrease the cooperativity of the substrate. 
D)  raise the apparent value of the equilibrium constant, L. 
E)  increase the likelihood of the binding of S. 
A)  cause a shift to the left in the sigmoidal curve. 
B)  increase the number of R conformations. 
C)  decrease the cooperativity of the substrate. 
D)  raise the apparent value of the equilibrium constant, L. 
E)  increase the likelihood of the binding of S.

Question 3

BPG shifts the oxygen saturation curve of Hb to the ____ because BPG binds to ____ making Hb an O2 delivery system eminently suited for ____.

Accepted Answer

A)  right; deoxyHb; humans and other primates 
B)  right; deoxyHb; cattle, sheep and goats 
C)  left; oxyHb; cattle, sheep and goats 
D)  left; oxyHb; humans and other primates 
E)  none of the above 
A)  right; deoxyHb; humans and other primates 
B)  right; deoxyHb; cattle, sheep and goats 
C)  left; oxyHb; cattle, sheep and goats 
D)  left; oxyHb; humans and other primates 
E)  none of the above

Question 4

Explain how 2,3-bisphosphoglycerate (BPG) and O2 are mutually exclusive allosteric effectors for hemoglobin (Hb).​

Accepted Answer

The strongly negative BPG molecule is el

Question 5

Which of the following will cause an increase in the activity of glycogen phosphorylase?

Accepted Answer

A)  binding of ATP to the allosteric site 
B)  phosphorylation of the enzyme 
C)  high levels of glucose-6-phosphate 
D)  conversion from the relaxed to tense state 
E)  drinking coffee 
A)  binding of ATP to the allosteric site 
B)  phosphorylation of the enzyme 
C)  high levels of glucose-6-phosphate 
D)  conversion from the relaxed to tense state 
E)  drinking coffee

Question 6

All of the following are characteristics of hemoglobin's binding of oxygen EXCEPT:

Accepted Answer

A)  CO2 promotes dissociation of O2 from hemoglobin by lowering the pH. 
B)  Protons promote binding of oxygen by Hb. 
C)  2,3-Bisphosphoglycerate (BPG) promotes release of O2 by Hb. 
D)  CO2 can bind with Hb's free amino groups and stabilize deoxy-Hb. 
E)  BPG and O2 are mutually exclusive allosteric effectors of Hb. 
A)  CO2 promotes dissociation of O2 from hemoglobin by lowering the pH. 
B)  Protons promote binding of oxygen by Hb. 
C)  2,3-Bisphosphoglycerate (BPG) promotes release of O2 by Hb. 
D)  CO2 can bind with Hb's free amino groups and stabilize deoxy-Hb. 
E)  BPG and O2 are mutually exclusive allosteric effectors of Hb.

Question 7

Fetal hemoglobin (Hb F) has an intrinsically greater affinity for O2

Than adult hemoglobin (Hb A) because:

Accepted Answer

A)  Hb F has a diminished capacity to bind BPG compared to Hb A. 
B)  Hb A has a greater affinity for oxygen than does Hb F. 
C)  BPG binds Hb F with greater affinity than it binds Hb A. 
D)  The pH of fetal blood is less than the pH of maternal blood. 
E)  All of the above are correct. 
A)  Hb F has a diminished capacity to bind BPG compared to Hb A. 
B)  Hb A has a greater affinity for oxygen than does Hb F. 
C)  BPG binds Hb F with greater affinity than it binds Hb A. 
D)  The pH of fetal blood is less than the pH of maternal blood. 
E)  All of the above are correct.

Question 8

All of the following are examples of a zymogen and its activating protease EXCEPT:

Accepted Answer

A)  chymotrypsinogen and chymotrypsin. 
B)  procarboxypeptidase and elastase. 
C)  proelastase and elastase. 
D)  pepsinogen and pepsin. 
E)  trypsinogen and trypsin. 
A)  chymotrypsinogen and chymotrypsin. 
B)  procarboxypeptidase and elastase. 
C)  proelastase and elastase. 
D)  pepsinogen and pepsin. 
E)  trypsinogen and trypsin.

Question 9

The addition of an effector to an enzyme that acts as a K system of the MWC model causes the half-maximum velocity (K0.5) to ____ and Vmax to ____.

Accepted Answer

A)  remain constant; remain constant 
B)  remain constant; change 
C)  change; remain constant 
D)  change; change 
E)  none of the above 
A)  remain constant; remain constant 
B)  remain constant; change 
C)  change; remain constant 
D)  change; change 
E)  none of the above

Question 10

The polypeptide of myoglobin serves all of the following functions EXCEPT:

Accepted Answer

A)  protects the heme iron from oxidation. 
B)  cradles the heme group. 
C)  provides a pocket for O2 to fit. 
D)  keeps the heme iron in the ferric form. 
E)  none of the above. 
A)  protects the heme iron from oxidation. 
B)  cradles the heme group. 
C)  provides a pocket for O2 to fit. 
D)  keeps the heme iron in the ferric form. 
E)  none of the above.

Question 11

All are true about isozymes of lactate dehydrogenase (LDH) that are present in a number of different tissues EXCEPT:

Accepted Answer

A)  They have differing Km values for lactate. 
B)  The amount of subunit phosphorylation differs. 
C)  They have differing Km values for pyruvate. 
D)  The ratios of A and B subunits differ depending upon the tissue type 
E)  They have different kinetic parameters. 
A)  They have differing Km values for lactate. 
B)  The amount of subunit phosphorylation differs. 
C)  They have differing Km values for pyruvate. 
D)  The ratios of A and B subunits differ depending upon the tissue type 
E)  They have different kinetic parameters.

Question 12

Carbon dioxide affects O2 binding to Hb by:

Accepted Answer

A)  Hb competing with carbonic anhydride for CO2. 
B)  directly binding to heme-Fe in the oxygen binding site. 
C)  forming iron carbonate with the heme-iron. 
D)  forming H+ + HCO3− where the H+ is an antagonist to oxygen binding to Hb. 
E)  forming HCO3− that combines with H+ to increase CO2 binding. 
A)  Hb competing with carbonic anhydride for CO2. 
B)  directly binding to heme-Fe in the oxygen binding site. 
C)  forming iron carbonate with the heme-iron. 
D)  forming H+ + HCO3− where the H+ is an antagonist to oxygen binding to Hb. 
E)  forming HCO3− that combines with H+ to increase CO2 binding.

Question 13

Explain allosteric inhibition with an example.​

Accepted Answer

Consider as an illustration the followin

Question 14

The Gα subunit of GTP-binding protein (G protein) has all of the following characteristics EXCEPT:

Accepted Answer

A)  activates adenylyl cyclase. 
B)  hormone-receptor complex promotes Gα release from Gβγ. 
C)  has a very active GTPase activity. 
D)  binds GDP in the Gαβγ complex. 
E)  GTP hydrolysis leads to Gα-adenylyl cyclase dissociation. 
A)  activates adenylyl cyclase. 
B)  hormone-receptor complex promotes Gα release from Gβγ. 
C)  has a very active GTPase activity. 
D)  binds GDP in the Gαβγ complex. 
E)  GTP hydrolysis leads to Gα-adenylyl cyclase dissociation.

Question 15

Which of the following statements regarding enzyme regulation is true?

Accepted Answer

A)  addition of an inhibitor to a V system results in kinetics similar to addition of a competitive inhibitor to a typical hyperbolic system 
B)  allosteric effectors are always more powerful than covalent modification 
C)  addition of an allosteric activator to a K system changes the plot of V vs. [S] from a sigmoidal curve to a more hyperbolic curve 
D)  the T state of an enzyme generally has more activity than the R state 
E)  none of the above are true 
A)  addition of an inhibitor to a V system results in kinetics similar to addition of a competitive inhibitor to a typical hyperbolic system 
B)  allosteric effectors are always more powerful than covalent modification 
C)  addition of an allosteric activator to a K system changes the plot of V vs. [S] from a sigmoidal curve to a more hyperbolic curve 
D)  the T state of an enzyme generally has more activity than the R state 
E)  none of the above are true

Question 16

Explain the KNF model of allosteric inhibition.​

Accepted Answer

The KNF model proposed by Daniel Koshlan

Question 17

The function of glycogen phosphorylase is:

Accepted Answer

A)  the conversion of glucose-1-phosphate to glucose-6-phosphate. 
B)  to break down ATP. 
C)  to catalyze the phosphorolysis of glucose-1-phosphate from glycogen molecules. 
D)  to inhibit the production of glucose-1-phosphate. 
E)  to stimulate the build up of glycogen. 
A)  the conversion of glucose-1-phosphate to glucose-6-phosphate. 
B)  to break down ATP. 
C)  to catalyze the phosphorolysis of glucose-1-phosphate from glycogen molecules. 
D)  to inhibit the production of glucose-1-phosphate. 
E)  to stimulate the build up of glycogen.

Question 18

Which of the following statements regarding enzyme regulation is true?

Accepted Answer

A)  the conversion of trypsinogen to trypsin is an example of zymogen activation 
B)  allosteric effectors are always more powerful than covalent modification 
C)  addition of an inhibitor to a V system results in kinetics similar to addition of a competitive inhibitor to a typical hyperbolic system 
D)  the T state of an enzyme generally has more activity than the R state 
E)  none of the above 
A)  the conversion of trypsinogen to trypsin is an example of zymogen activation 
B)  allosteric effectors are always more powerful than covalent modification 
C)  addition of an inhibitor to a V system results in kinetics similar to addition of a competitive inhibitor to a typical hyperbolic system 
D)  the T state of an enzyme generally has more activity than the R state 
E)  none of the above

Question 19

An enzyme that displays negative cooperativity has ____ activity when the substrate is present at concentrations ____ than the value of K0.5 when compared with enzymes that display no cooperativity.

Accepted Answer

A)  increased; greater 
B)  increased; less 
C)  decreased; greater 
D)  decreased; less 
E)  both b and c are correct 
A)  increased; greater 
B)  increased; less 
C)  decreased; greater 
D)  decreased; less 
E)  both b and c are correct

Question 20

When O2 binds to heme in hemoglobin, the ____ ion is drawn into the plane of the ____ causing a conformational change that is transmitted to adjacent subunits enhancing the ____ for additional O2 binding.

Accepted Answer

A)  Mg2+; globin; planarity 
B)  Fe3+; heme; folding 
C)  Mg2+; globin; attraction 
D)  Fe3+; porphyrin; affinity 
E)  Fe2+; porphyrin; affinity 
A)  Mg2+; globin; planarity 
B)  Fe3+; heme; folding 
C)  Mg2+; globin; attraction 
D)  Fe3+; porphyrin; affinity 
E)  Fe2+; porphyrin; affinity

Exam 15: Enzyme Regulation

We are protected to some extent against low level CO poisoning because:

The presence of a negative allosteric effector on an allosteric protein would:

BPG shifts the oxygen saturation curve of Hb to the ____ because BPG binds to ____ making Hb an O2 delivery system eminently suited for ____.

Explain how 2,3-bisphosphoglycerate (BPG) and O2 are mutually exclusive allosteric effectors for hemoglobin (Hb).​

Which of the following will cause an increase in the activity of glycogen phosphorylase?

All of the following are characteristics of hemoglobin's binding of oxygen EXCEPT:

Fetal hemoglobin (Hb F) has an intrinsically greater affinity for O2 Than adult hemoglobin (Hb A) because:

All of the following are examples of a zymogen and its activating protease EXCEPT:

The addition of an effector to an enzyme that acts as a K system of the MWC model causes the half-maximum velocity (K0.5) to ____ and Vmax to ____.

The polypeptide of myoglobin serves all of the following functions EXCEPT:

All are true about isozymes of lactate dehydrogenase (LDH) that are present in a number of different tissues EXCEPT:

Carbon dioxide affects O2 binding to Hb by:

Explain allosteric inhibition with an example.​

The Gα subunit of GTP-binding protein (G protein) has all of the following characteristics EXCEPT:

Which of the following statements regarding enzyme regulation is true?

Explain the KNF model of allosteric inhibition.​

The function of glycogen phosphorylase is:

Which of the following statements regarding enzyme regulation is true?

An enzyme that displays negative cooperativity has ____ activity when the substrate is present at concentrations ____ than the value of K0.5 when compared with enzymes that display no cooperativity.

When O2 binds to heme in hemoglobin, the ____ ion is drawn into the plane of the ____ causing a conformational change that is transmitted to adjacent subunits enhancing the ____ for additional O2 binding.

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

BPG shifts the oxygen saturation curve of Hb to the because BPG binds to making Hb an O₂ delivery system eminently suited for .

Explain how 2,3-bisphosphoglycerate (BPG) and O₂ are mutually exclusive allosteric effectors for hemoglobin (Hb).

Fetal hemoglobin (Hb F) has an intrinsically greater affinity for O₂ Than adult hemoglobin (Hb A) because:

The addition of an effector to an enzyme that acts as a K system of the MWC model causes the half-maximum velocity (K_0.5) to ____ and V_max to ____.

Carbon dioxide affects O₂ binding to Hb by:

Explain allosteric inhibition with an example.

Explain the KNF model of allosteric inhibition.

An enzyme that displays negative cooperativity has activity when the substrate is present at concentrations than the value of K0.5 when compared with enzymes that display no cooperativity.

When O₂ binds to heme in hemoglobin, the ion is drawn into the plane of the causing a conformational change that is transmitted to adjacent subunits enhancing the for additional O₂ binding.