Biochemistry Exam 2 Multiple Choice
What is the organic portion of the heme group in hemoglobin? - answersProtoporphyrin
Define superoxide. - answersA 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? - answersBicarbonate 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. - answersHistidine
Define myoglobin. - answersMolecule whose function is to store oxygen in muscle cells
What type of binding is indicated by a sigmoidal-shaped binding curve? -
answersCooperative
Under normal conditions, the heme iron in myoglobin and hemoglobin is in what
oxidation state? - answersFe2+
How can the structure of normal adult hemoglobin be described? - answersA tetramer
composed of two alpha-beta dimers
True or false: Hemoglobin exhibits cooperative binding of O2 while myoglobin does not.
- answersTrue
True or false: Both myoglobin and hemoglobin are tetrametric proteins. - answersFalse
True or false: Hemoglobin exhibits a hyperbolic O2 saturation curve while myoglobin
exhibits a sigmoid shaped curve. - answersFalse
True or false: Hemoglobin exhibits a higher degree of O2 saturation at all physiologically
relevant partial pressures of O2 than does myoglobin. - answersFalse
Hemoglobin's binding of oxygen is best described as what? - answersCombination of
sequential and concerted models
What factor influences the binding of oxygen to myoglobin? - answersThe partial
pressure of oxygen, pO2
, True or false: Concerning myoglobin, the globin chain contains an extensive alpha-helix
structure. - answersTrue
True or false: Concerning myoglobin, the heme group is bound to the globin chain by
two disulfide bonds to cysteine residues. - answersFalse
True or false: Concerning myoglobin, the iron of the heme group is in the Fe3+
oxidation state. - answersFalse - Fe2+
True or false: Concerning myoglobin, the diameter of the iron ion decreases upon
binding to oxygen. - answersTrue
What is true regarding hemoglobin and oxygen transport? - answersHemoglobin binds
more oxygen as the pH is lowered
What is sickle-cell anemia caused by? - answersSubstitution of a Val residue for a Glu
residue at the beta-6 position
Carbon dioxide forms carbamate groups in proteins by reaction with what? - answersN-
terminal amino groups
The function of what molecule is the storage of oxygen in muscle cells? -
answersMyoglobin
Carbon dioxide reacts with amino terminal groups of hemoglobin to form carbamate
groups, which carry a _____ charge. - answersNegative
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, an increase in
the pressure of CO2 will result in a decrease of pH. - answersTrue
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, this reaction
is catalyzed by carbonic anhydrase. - answersTrue
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, H2CO3 does
not dissociate to H+ and bicarbonate ion, HCO3-. - answersFalse
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, the majority
of CO2 is transported to the lungs in the form of HCO3-. - answersTrue
Enzymes that do not have the required cofactor bound are called what? -
answersHoloenzymes
What is the site on the enzyme where the reaction occurs called? - answersActive site
What is the organic portion of the heme group in hemoglobin? - answersProtoporphyrin
Define superoxide. - answersA 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? - answersBicarbonate 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. - answersHistidine
Define myoglobin. - answersMolecule whose function is to store oxygen in muscle cells
What type of binding is indicated by a sigmoidal-shaped binding curve? -
answersCooperative
Under normal conditions, the heme iron in myoglobin and hemoglobin is in what
oxidation state? - answersFe2+
How can the structure of normal adult hemoglobin be described? - answersA tetramer
composed of two alpha-beta dimers
True or false: Hemoglobin exhibits cooperative binding of O2 while myoglobin does not.
- answersTrue
True or false: Both myoglobin and hemoglobin are tetrametric proteins. - answersFalse
True or false: Hemoglobin exhibits a hyperbolic O2 saturation curve while myoglobin
exhibits a sigmoid shaped curve. - answersFalse
True or false: Hemoglobin exhibits a higher degree of O2 saturation at all physiologically
relevant partial pressures of O2 than does myoglobin. - answersFalse
Hemoglobin's binding of oxygen is best described as what? - answersCombination of
sequential and concerted models
What factor influences the binding of oxygen to myoglobin? - answersThe partial
pressure of oxygen, pO2
, True or false: Concerning myoglobin, the globin chain contains an extensive alpha-helix
structure. - answersTrue
True or false: Concerning myoglobin, the heme group is bound to the globin chain by
two disulfide bonds to cysteine residues. - answersFalse
True or false: Concerning myoglobin, the iron of the heme group is in the Fe3+
oxidation state. - answersFalse - Fe2+
True or false: Concerning myoglobin, the diameter of the iron ion decreases upon
binding to oxygen. - answersTrue
What is true regarding hemoglobin and oxygen transport? - answersHemoglobin binds
more oxygen as the pH is lowered
What is sickle-cell anemia caused by? - answersSubstitution of a Val residue for a Glu
residue at the beta-6 position
Carbon dioxide forms carbamate groups in proteins by reaction with what? - answersN-
terminal amino groups
The function of what molecule is the storage of oxygen in muscle cells? -
answersMyoglobin
Carbon dioxide reacts with amino terminal groups of hemoglobin to form carbamate
groups, which carry a _____ charge. - answersNegative
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, an increase in
the pressure of CO2 will result in a decrease of pH. - answersTrue
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, this reaction
is catalyzed by carbonic anhydrase. - answersTrue
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, H2CO3 does
not dissociate to H+ and bicarbonate ion, HCO3-. - answersFalse
True or false: Concerning the equilibrium equation CO2 + H2O = H2CO3, the majority
of CO2 is transported to the lungs in the form of HCO3-. - answersTrue
Enzymes that do not have the required cofactor bound are called what? -
answersHoloenzymes
What is the site on the enzyme where the reaction occurs called? - answersActive site
