hemoglobin and myoglobin self test Flashcards
The most important biological function of the distal histidine of hemoglobin is:
Coordinate to the iron of the heme.
a. Trigger the conformational change from the T-state to the R-state.
b. Bind a proton that contributes to the Bohr effect.
c. To decrease the affinity of the heme for carbon monoxide.
d. All of these.
To decrease the affinity of the heme for carbon monoxide.
When a glutamic acid residue is brought into close proximity to an aspartate residue the pKa of the
glutamic acid residue ______________________.
a. increases
b. No answer text provided.
c. remain unchanged
d. decreases
What is the source of the cooperativity of hemoglobin?
Group of answer choices
The Bohr effect
The quaternary interactions between subunits
His F8
His E7
The movement of the iron atom coordinated to the heme
The quaternary interactions between subunits
Which of the following statements about the oxidation state of iron is true?
Group of answer choices
None of these statements are true.
A water molecule binds to the heme bound iron when the iron is in the ferrous state.
The iron center of the heme in Methemoglobin is in the Fe2+ state.
The binding of oxygen in homoglobin or myglobin, oxidizes the heme iron from the Fe2+ to teh Fe3+ state.
Oxygen binds to the heme bound iron when the iron is in the ferric state.
None of these statements are true.
Increasing the pH from 7.2 to 7.4 would:
Group of answer choices
Increase the O2 binding affinity of myoglobin.
Have no effect on the O2 binding affinity of hemoglobin
Decrease the O2 binding affinity of myoglobin.
Decrease the O2 binding affinity of hemoglobin.
Increase the O2 binding affinity of hemoglobin.
Increase the O2 binding affinity of hemoglobin.
If the pH decrease from 7.4 to 7.3, the p50 of hemoglobin would
Group of answer choices
none of these.
remain unchanged.
decrease.
cannot be determined.
increase.
remain unchanged.
When the pH decreases from 7.4 to 7.2, the oxygen affinity of myoglobin ____________________.
Group of answer choices
increases
decreases
remain unchanged
remain unchanged
Which of the following statements about the oxidation state of iron is not true?
Group of answer choices
The binding of oxygen in hemoglobin or myglobin, oxidizes the heme iron from the Fe2+ to the
Fe3+ state.
Oxygen binds to the heme bound iron when the iron is in the ferrous state.
The iron center of the heme in Methemoglobin is in the Fe3+ state.
A water molecule binds to the heme bound iron when the iron is in the ferric state.
All of these statements are not true.
The binding of oxygen in hemoglobin or myglobin, oxidizes the heme iron from the Fe2+ to the
Fe3+ state.
When a glutamic acid residue is shifted from the surface of a protein into a hydrophobic, nonpolar
pocket in the interior of the protein, the pKa of the glutamic acid _______________________.
Group of answer choices
increases
decreases
No answer text provided.
remain unchanged
increases
Hemoglobin carries CO2 from the tissues back to the lungs by
Group of answer choices
Coordinating the CO2 to the iron of the hemes
Binding CO2 in the central cavity of hemoglobin
Carbamylation of N-terminals of the 4 polypeptide chains.
Converting CO2 to bicarbonate.
None of these
Carbamylation of N-terminals of the 4 polypeptide chains.
In both hemoglobin and myoglobin, the role of the proximal histidine is to:
Group of answer choices
Coordinate to the heme iron.
Bind a proton that contributes to the Bohr effect.
Participate in oxygen binding by forming a hydrogen bond with O2.
Participate in the binding 2, 3 Bisphosphoglycerate.
Protect iron atom from being oxidized into the ferric state.
Coordinate to the heme iron.
As oxygen binds to the Hb subunits:
Group of answer choices
Each heme rotates 15o triggering the T
R transformation.
The oxygen displaces His E7 releasing the E helix to trigger the T
R transformation.
His F8 dissociates from heme iron coordination to trigger the T
R transformation.
His F8 pulls the iron atom out of the plane of the heme to trigger the T
R transformation.
The iron atom moves into the plane of the heme to trigger the T
R transformation.
The iron atom moves into the plane of the heme to trigger the T
R transformation.
If you took off last Wednesday evening leaving TAMU elevation near sea level and went to party at
the Octoberfest in the rockin’ ski lodge town of Park City, Utah elevation 10,000 feet (beautiful this
time of year). Your body would adapt to the lower oxygen concentration by,
Group of answer choices
Decreasing the physiological pH.
Increase the cellular concentration of Alcohol dehydrogenase.
Increasing the physiological pH.
Increasing the BPG concentration.
Increasing the carbonic anhydrase concentration.
Increasing the BPG concentration.
When a histidine residue is brought into close proximity to an aspartate residue the pKa of the
histidine __________________.
Group of answer choices
remain unchanged
decreases
increases
increases
When the concentration of BPG decreases, the oxygen affinity of hemoglobin__________________.
Group of answer choices
remain unchanged
decreases
increases
increases
