BIOCHEMISTRY EXAM 2 (MULTIPLE CHOICE)
What is the organic portion of the heme group in hemoglobin? - Answers -
Protoporphyrin
Define superoxide. - Answers - A reactive oxygen species that is damaging to biological
materials
What is the chemical form in which most of the carbon dioxide is transported in the
blood? - Answers - Bicarbonate ion
In hemoglobin, the iron of the heme is bonded to the four nitrogens of porphyrin and to
the proximal _____ residue of the globin chain. - Answers - Histidine
Define myoglobin. - Answers - Molecule whose function is to store oxygen in muscle
cells
What type of binding is indicated by a sigmoidal-shaped binding curve? - Answers -
Cooperative
Under normal conditions, the heme iron in myoglobin and hemoglobin is in what
oxidation state? - Answers - Fe2+
Hemoglobin's binding of oxygen is best described as what? - Answers - Combination of
sequential and concerted models
What factor influences the binding of oxygen to myoglobin? - Answers - The partial
pressure of oxygen, pO2
True or false: Concerning myoglobin, the globin chain contains an extensive alpha-helix
structure. - Answers - True
True or false: Concerning myoglobin, the heme group is bound to the globin chain by
two disulfide bonds to cysteine residues. - Answers - False
True or false: Concerning myoglobin, the iron of the heme group is in the Fe3+ oxidation
state. - Answers - False - Fe2+
True or false: Concerning myoglobin, the diameter of the iron ion decreases upon
binding to oxygen. - Answers - True
What is true regarding hemoglobin and oxygen transport? - Answers - Hemoglobin
binds more oxygen as the pH is lowered
, What is sickle-cell anemia caused by? - Answers - Substitution of a Val residue for a Glu
residue at the beta-6 position
Carbon dioxide forms carbamate groups in proteins by reaction with what? - Answers -
N-terminal amino groups
The function of what molecule is the storage of oxygen in muscle cells? - Answers -
Myoglobin
How can the structure of normal adult hemoglobin be described? - Answers - A tetramer
composed of two alpha-beta dimers
True or false: Hemoglobin exhibits cooperative binding of O2 while myoglobin does not.
- Answers - True
True or false: Both myoglobin and hemoglobin are tetrametric proteins. - Answers -
False
True or false: Hemoglobin exhibits a hyperbolic O2 saturation curve while myoglobin
exhibits a sigmoid shaped curve. - Answers - False
True or false: Hemoglobin exhibits a higher degree of O2 saturation at all physiologically
relevant partial pressures of O2 than does myoglobin. - Answers – False
Carbon dioxide reacts with amino terminal groups of hemoglobin to form carbamate
groups, which carry a _____ charge. - Answers - Negative
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, an increase in
the pressure of CO2 will result in a decrease of pH. - Answers - True
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, this reaction
is catalyzed by carbonic anhydrase. - Answers - True
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, H2CO3 does
not dissociate to H+ and bicarbonate ion, HCO3-. - Answers - False
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, the majority of
CO2 is transported to the lungs in the form of HCO3-. - Answers - True
Enzymes that do not have the required cofactor bound are called what? - Answers -
Holoenzymes
What is the site on the enzyme where the reaction occurs called? - Answers - Active site
The difference between the standard-state free energy, delta-G naught, and the
biochemical standard-state free energy, delta-G naught prime, is that delta-G naught
prime refers to the standard free-energy change at what? - Answers - pH = 7
What is the organic portion of the heme group in hemoglobin? - Answers -
Protoporphyrin
Define superoxide. - Answers - A reactive oxygen species that is damaging to biological
materials
What is the chemical form in which most of the carbon dioxide is transported in the
blood? - Answers - Bicarbonate ion
In hemoglobin, the iron of the heme is bonded to the four nitrogens of porphyrin and to
the proximal _____ residue of the globin chain. - Answers - Histidine
Define myoglobin. - Answers - Molecule whose function is to store oxygen in muscle
cells
What type of binding is indicated by a sigmoidal-shaped binding curve? - Answers -
Cooperative
Under normal conditions, the heme iron in myoglobin and hemoglobin is in what
oxidation state? - Answers - Fe2+
Hemoglobin's binding of oxygen is best described as what? - Answers - Combination of
sequential and concerted models
What factor influences the binding of oxygen to myoglobin? - Answers - The partial
pressure of oxygen, pO2
True or false: Concerning myoglobin, the globin chain contains an extensive alpha-helix
structure. - Answers - True
True or false: Concerning myoglobin, the heme group is bound to the globin chain by
two disulfide bonds to cysteine residues. - Answers - False
True or false: Concerning myoglobin, the iron of the heme group is in the Fe3+ oxidation
state. - Answers - False - Fe2+
True or false: Concerning myoglobin, the diameter of the iron ion decreases upon
binding to oxygen. - Answers - True
What is true regarding hemoglobin and oxygen transport? - Answers - Hemoglobin
binds more oxygen as the pH is lowered
, What is sickle-cell anemia caused by? - Answers - Substitution of a Val residue for a Glu
residue at the beta-6 position
Carbon dioxide forms carbamate groups in proteins by reaction with what? - Answers -
N-terminal amino groups
The function of what molecule is the storage of oxygen in muscle cells? - Answers -
Myoglobin
How can the structure of normal adult hemoglobin be described? - Answers - A tetramer
composed of two alpha-beta dimers
True or false: Hemoglobin exhibits cooperative binding of O2 while myoglobin does not.
- Answers - True
True or false: Both myoglobin and hemoglobin are tetrametric proteins. - Answers -
False
True or false: Hemoglobin exhibits a hyperbolic O2 saturation curve while myoglobin
exhibits a sigmoid shaped curve. - Answers - False
True or false: Hemoglobin exhibits a higher degree of O2 saturation at all physiologically
relevant partial pressures of O2 than does myoglobin. - Answers – False
Carbon dioxide reacts with amino terminal groups of hemoglobin to form carbamate
groups, which carry a _____ charge. - Answers - Negative
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, an increase in
the pressure of CO2 will result in a decrease of pH. - Answers - True
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, this reaction
is catalyzed by carbonic anhydrase. - Answers - True
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, H2CO3 does
not dissociate to H+ and bicarbonate ion, HCO3-. - Answers - False
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, the majority of
CO2 is transported to the lungs in the form of HCO3-. - Answers - True
Enzymes that do not have the required cofactor bound are called what? - Answers -
Holoenzymes
What is the site on the enzyme where the reaction occurs called? - Answers - Active site
The difference between the standard-state free energy, delta-G naught, and the
biochemical standard-state free energy, delta-G naught prime, is that delta-G naught
prime refers to the standard free-energy change at what? - Answers - pH = 7
