Question 1

Which of the following statements best characterizes an antibody?

Accepted Answer

A)  An antibody contains high molecular weight RNA as its basic structure. 
B)  An antibody is composed of protein and cannot be distinguished from the albumin fraction of the serum proteins. 
C)  An antibody is composed of four identical protein subunits which may be caused to dissociate by treatment with urea. 
D)  An antibody contains protein as its major chemical component and its synthesis may be elicited by the administration of a foreign protein or polysaccharide. 
E)  An antibody contains mucopolysaccharides as its major chemical component and the synthesis of these may be elicited by the administration of a foreign protein or polysaccharide. 
A)  An antibody contains high molecular weight RNA as its basic structure. 
B)  An antibody is composed of protein and cannot be distinguished from the albumin fraction of the serum proteins. 
C)  An antibody is composed of four identical protein subunits which may be caused to dissociate by treatment with urea. 
D)  An antibody contains protein as its major chemical component and its synthesis may be elicited by the administration of a foreign protein or polysaccharide. 
E)  An antibody contains mucopolysaccharides as its major chemical component and the synthesis of these may be elicited by the administration of a foreign protein or polysaccharide.

Question 2

Which of the following is a correct statement regarding the structure of a IgG antibody?

Accepted Answer

A)  It is a protein with a small percentage of carbohydrate attached. 
B)  It is a carbohydrate with a small amount of protein attached. 
C)  It is a protein with an equal weight of carbohydrate attached. 
D)  It is a protein with a small amount of phospholipid attached. 
E)  It is a complex of protein, carbohydrate and lipid. 
A)  It is a protein with a small percentage of carbohydrate attached. 
B)  It is a carbohydrate with a small amount of protein attached. 
C)  It is a protein with an equal weight of carbohydrate attached. 
D)  It is a protein with a small amount of phospholipid attached. 
E)  It is a complex of protein, carbohydrate and lipid.

Question 3

Oxygen dissociation from Hb is facilitated by all of the following EXCEPT which one?
Oxygen dissociation from Hb is facilitated by all of the following EXCEPT which one?

Accepted Answer

A)  low PO2 
B)  high PCO2 
C)  high temperature 
D)  high pH 
E)  high levels of 2,3-BPG 
A)  low PO2 
B)  high PCO2 
C)  high temperature 
D)  high pH 
E)  high levels of 2,3-BPG

Question 4

Basement membrane is composed of basal lamina and another component. What is this other component?

Accepted Answer

A)  Fibrillar collagen 
B)  Fibrinogen 
C)  Heparin sulfate 
D)  Proteases 
E)  Proteoglycan 
A)  Fibrillar collagen 
B)  Fibrinogen 
C)  Heparin sulfate 
D)  Proteases 
E)  Proteoglycan

Question 5

The difference in P50 values of fetal and adult hemoglobins is best explained by a difference in the

Accepted Answer

A)  binding of nitric oxide. 
B)  extent of subunit cooperativity. 
C)  interaction with an allosteric effector. 
D)  number of alpha-globin subunits. 
A)  binding of nitric oxide. 
B)  extent of subunit cooperativity. 
C)  interaction with an allosteric effector. 
D)  number of alpha-globin subunits.

Question 6

Deoxyhemoglobin contains:

Accepted Answer

A)  Fe2+ 
B)  CO 
C)  H20 bound to Fe3+ 
D)  four beta chains 
E)  fewer protons than oxyhemoglobin. 
A)  Fe2+ 
B)  CO 
C)  H20 bound to Fe3+ 
D)  four beta chains 
E)  fewer protons than oxyhemoglobin.

Question 7

A high PCO2 would tend to decrease the blood pH by forming carbonic acid. However, it also stimulates the release of oxygen from oxyhemoglobin, and this minimizes the pH change because

Accepted Answer

A)  deoxyhemoglobin is a weaker acid than oxyhemoglobin. 
B)  the hemoglobin iron undergoes alternate oxidation and reduction. 
C)  the heme group is in a hydrophobic environment. 
D)  deoxyhemoglobin is a stronger acid than oxyhemoglobin. 
E)  hemoglobin has less binding capacity for oxygen than myoglobin. 
A)  deoxyhemoglobin is a weaker acid than oxyhemoglobin. 
B)  the hemoglobin iron undergoes alternate oxidation and reduction. 
C)  the heme group is in a hydrophobic environment. 
D)  deoxyhemoglobin is a stronger acid than oxyhemoglobin. 
E)  hemoglobin has less binding capacity for oxygen than myoglobin.

Question 8

All of the following statements regarding the interaction of hemoglobin with oxygen are true EXCEPT

Accepted Answer

A)  in Hb A, each heme prosthetic group is capable of reversibly binding one oxygen molecule. 
B)  the oxygen molecule binds to the heme prosthetic group on the surface opposite to that occupied by the F8 - His. 
C)  the effect of oxygenation on a heme prosthetic group is such as to push the F8 - His farther from the plane of the heme ring. 
D)  the reversible binding of an oxygen molecule to a heme prosthetic group requires that the iron of the heme be in the divalent state. 
E)  oxygenated hemoglobin is a stronger acid than deoxygenated hemoglobin. 
A)  in Hb A, each heme prosthetic group is capable of reversibly binding one oxygen molecule. 
B)  the oxygen molecule binds to the heme prosthetic group on the surface opposite to that occupied by the F8 - His. 
C)  the effect of oxygenation on a heme prosthetic group is such as to push the F8 - His farther from the plane of the heme ring. 
D)  the reversible binding of an oxygen molecule to a heme prosthetic group requires that the iron of the heme be in the divalent state. 
E)  oxygenated hemoglobin is a stronger acid than deoxygenated hemoglobin.

Question 9

The regions of variable amino acid composition of immunoglobulins occur in

Accepted Answer

A)  heavy chains only. 
B)  light chains only. 
C)  both light and heavy chains. 
D)  IgG but not other immunoglobulins. 
E)  IgE but not other immunoglobulins. 
A)  heavy chains only. 
B)  light chains only. 
C)  both light and heavy chains. 
D)  IgG but not other immunoglobulins. 
E)  IgE but not other immunoglobulins.

Question 10

The quaternary structure of hemoglobin is

Accepted Answer

A)  not important for the functioning of this protein. 
B)  rigid and is not affected by oxygen binding. 
C)  maintained by hydrophobic bonds, salt bridges, and hydrogen bonds. 
D)  stabilized by disulfide bridges. 
E)  none of the above 
A)  not important for the functioning of this protein. 
B)  rigid and is not affected by oxygen binding. 
C)  maintained by hydrophobic bonds, salt bridges, and hydrogen bonds. 
D)  stabilized by disulfide bridges. 
E)  none of the above

Question 11

The structure of myoglobin, as determined by x-ray diffraction, exhibits all of the following EXCEPT which one?

Accepted Answer

A)  The heme group is tucked into a pocket or cleft of the myoglobin molecule. 
B)  The myoglobin molecule has almost the same alpha helical content as the individual subunits of the hemoglobin molecule. 
C)  The myoglobin molecule has a very similar tertiary structure to the individual subunits of the hemoglobin molecule. 
D)  There is almost no water in the interior of the molecule. 
E)  The heme iron is linked to a tyrosine residue at its fifth coordination position. 
A)  The heme group is tucked into a pocket or cleft of the myoglobin molecule. 
B)  The myoglobin molecule has almost the same alpha helical content as the individual subunits of the hemoglobin molecule. 
C)  The myoglobin molecule has a very similar tertiary structure to the individual subunits of the hemoglobin molecule. 
D)  There is almost no water in the interior of the molecule. 
E)  The heme iron is linked to a tyrosine residue at its fifth coordination position.

Question 12

The Fe2+ atom in hemoglobin can be bonded to 6 coordinate ligands. What are the six coordinate ligands of ferrous iron bonded to?

Accepted Answer

A)  4 to the porphyrin ring, 1 to the proximal histidine, 1 to the distal histidine 
B)  4 to the porphyrin ring, 1 to the proximal histidine, 1 to oxygen 
C)  4 to the porphyrin ring, 1 to the distal histidine, 1 to oxygen 
D)  1 to oxygen, 5 to histidines in the hemoglobin polypeptide 
E)  the ferrous iron only binds to CO2 
A)  4 to the porphyrin ring, 1 to the proximal histidine, 1 to the distal histidine 
B)  4 to the porphyrin ring, 1 to the proximal histidine, 1 to oxygen 
C)  4 to the porphyrin ring, 1 to the distal histidine, 1 to oxygen 
D)  1 to oxygen, 5 to histidines in the hemoglobin polypeptide 
E)  the ferrous iron only binds to CO2

Question 13

Which of the following correctly describes the quaternary structure of fetal hemoglobin?

Accepted Answer

A)  4 epsilon chains 
B)  2 alpha - 2 delta chains 
C)  2 alpha - 2 epsilon chains 
D)  2 alpha - 2 gamma chains 
E)  2 alpha - 2 beta chains 
A)  4 epsilon chains 
B)  2 alpha - 2 delta chains 
C)  2 alpha - 2 epsilon chains 
D)  2 alpha - 2 gamma chains 
E)  2 alpha - 2 beta chains

Question 14

What is the shape of the three polypeptide chains in the laminin molecule?

Accepted Answer

A)  Circular 
B)  Cruciform 
C)  Rectangular 
D)  Triangular 
E)  Tubular 
A)  Circular 
B)  Cruciform 
C)  Rectangular 
D)  Triangular 
E)  Tubular

Question 15

The sigmoid (S-shaped) binding curve that describes the interaction of O2 with hemoglobin is a direct consequence of

Accepted Answer

A)  allosteric regulation by 2,3-bisphosphoglycerate. 
B)  cooperativity among subunits. 
C)  covalent bonds between alpha beta?heterodimers. 
D)  orientation of histidine residues near the heme groups. 
E)  reversible oxidation and reduction of heme iron atoms. 
A)  allosteric regulation by 2,3-bisphosphoglycerate. 
B)  cooperativity among subunits. 
C)  covalent bonds between alpha beta?heterodimers. 
D)  orientation of histidine residues near the heme groups. 
E)  reversible oxidation and reduction of heme iron atoms.

Question 16

The heme group of myoglobin

Accepted Answer

A)  contains ferric ion. 
B)  is bound to the polypeptide chain exclusively by interactions between polar groups. 
C)  binds oxygen in an allosteric manner. 
D)  is identical to that of hemoglobin. 
E)  is bound to the polypeptide chain exclusively by interactions between nonpolar groups. 
A)  contains ferric ion. 
B)  is bound to the polypeptide chain exclusively by interactions between polar groups. 
C)  binds oxygen in an allosteric manner. 
D)  is identical to that of hemoglobin. 
E)  is bound to the polypeptide chain exclusively by interactions between nonpolar groups.

Question 17

Which of the following features of the hemoglobin molecule is considered part of its secondary structure?

Accepted Answer

A)  subunit interactions 
B)  sequence of amino acids 
C)  alpha helices 
D)  ligand binding properties 
E)  electrophoretic mobility 
A)  subunit interactions 
B)  sequence of amino acids 
C)  alpha helices 
D)  ligand binding properties 
E)  electrophoretic mobility

Question 18

The transition from the taut (deoxy) form of hemoglobin to the relaxed (oxy) form of hemoglobin involves the breaking of inter-subunit bonds that are predominately

Accepted Answer

A)  covalent. 
B)  van der Waal's 
C)  hydrophobic 
D)  ionic 
E)  none of the above 
A)  covalent. 
B)  van der Waal's 
C)  hydrophobic 
D)  ionic 
E)  none of the above

Question 19

The dissociated subunits of hemoglobin have a much higher affinity for oxygen than the intact molecule. Which of the following is the most likely explanation?

Accepted Answer

A)  BPG can interact much more readily with the dissociated subunits. 
B)  The iron atom moves out of the plane of the heme. 
C)  The heme dissociates from the globin. 
D)  The Bohr effect operates more effectively. 
E)  The allosteric effects reducing oxygen affinity require the intact tetramer. 
A)  BPG can interact much more readily with the dissociated subunits. 
B)  The iron atom moves out of the plane of the heme. 
C)  The heme dissociates from the globin. 
D)  The Bohr effect operates more effectively. 
E)  The allosteric effects reducing oxygen affinity require the intact tetramer.

Question 20

Each of the following statements is correct EXCEPT which one?

Accepted Answer

A)  Heme is the prosthetic group of myoglobin and certain cytochromes. 
B)  The ring structure of heme is composed of four pyrrole rings linked by one-carbon bridges. 
C)  In hemoglobin, one of the coordinate covalent linkages of each iron atom is to a histidine nitrogen. 
D)  The phenomenon of cooperativity is observed in the binding of oxygen to myoglobin. 
E)  The binding of BPG to beta chains of Hb decreases the affinity of alpha chains for oxygen. 
A)  Heme is the prosthetic group of myoglobin and certain cytochromes. 
B)  The ring structure of heme is composed of four pyrrole rings linked by one-carbon bridges. 
C)  In hemoglobin, one of the coordinate covalent linkages of each iron atom is to a histidine nitrogen. 
D)  The phenomenon of cooperativity is observed in the binding of oxygen to myoglobin. 
E)  The binding of BPG to beta chains of Hb decreases the affinity of alpha chains for oxygen.

Exam 9: Protein II: Structure-Function Relationships in Protein Families

Which of the following statements best characterizes an antibody?

Which of the following is a correct statement regarding the structure of a IgG antibody?

Oxygen dissociation from Hb is facilitated by all of the following EXCEPT which one? Oxygen dissociation from Hb is facilitated by all of the following EXCEPT which one?

Basement membrane is composed of basal lamina and another component. What is this other component?

The difference in P50 values of fetal and adult hemoglobins is best explained by a difference in the

Deoxyhemoglobin contains:

A high PCO2 would tend to decrease the blood pH by forming carbonic acid. However, it also stimulates the release of oxygen from oxyhemoglobin, and this minimizes the pH change because

All of the following statements regarding the interaction of hemoglobin with oxygen are true EXCEPT

The regions of variable amino acid composition of immunoglobulins occur in

The quaternary structure of hemoglobin is

The structure of myoglobin, as determined by x-ray diffraction, exhibits all of the following EXCEPT which one?

The Fe2+ atom in hemoglobin can be bonded to 6 coordinate ligands. What are the six coordinate ligands of ferrous iron bonded to?

Which of the following correctly describes the quaternary structure of fetal hemoglobin?

What is the shape of the three polypeptide chains in the laminin molecule?

The sigmoid (S-shaped) binding curve that describes the interaction of O2 with hemoglobin is a direct consequence of

The heme group of myoglobin

Which of the following features of the hemoglobin molecule is considered part of its secondary structure?

The transition from the taut (deoxy) form of hemoglobin to the relaxed (oxy) form of hemoglobin involves the breaking of inter-subunit bonds that are predominately

The dissociated subunits of hemoglobin have a much higher affinity for oxygen than the intact molecule. Which of the following is the most likely explanation?

Each of the following statements is correct EXCEPT which one?

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

Enzymes: Classification, Kinetics, and Control

The Cytochromes P450 and Nitric Oxide Synthases

Biological Membranes: Structure and Membrane Transport

Fundamentals of Signal Transduction

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

A high PCO₂ would tend to decrease the blood pH by forming carbonic acid. However, it also stimulates the release of oxygen from oxyhemoglobin, and this minimizes the pH change because

The Fe²⁺ atom in hemoglobin can be bonded to 6 coordinate ligands. What are the six coordinate ligands of ferrous iron bonded to?

The sigmoid (S-shaped) binding curve that describes the interaction of O₂ with hemoglobin is a direct consequence of