Haemoglobin A, F, S - Exam Questions Flashcards
What is myoglobin?
A monomer
Compared to myoglobin, haemoglobin
a. has a greater affinity for oxygen
b. has a lesser affinity for oxygen
c. has the same affinity for oxygen
d. may have a greater or lesser affinity for oxygen depending on
subtype
e. has a greater affinity in some tissues but a lesser affinity in others
b. compared to myoglobin, haemoglobin has a lesser affinity for oxygen so oxygen is released from haemoglobin to be picked up by the myoglobin in muscle cells.
What are the oxygen saturation curves for haemoglobin and myoglobin?
Sigmoidal for haemoglobin and a hyperbola for myoglobin.
The Bohr effect is that
a. an increase in pH and increase in [CO2] decreases haemoglobin’s
affinity for O2
b. an increase in pH and decrease in [CO2] decreases haemoglobin’s
affinity for O2
c. an increase in pH and increase in [CO2] increases haemoglobin’s
affinity for O2
d. an increase in pH and decrease in [CO2] increases haemoglobin’s
affinity for O2
e. an increase in pH and decrease in [CO2] increases haemoglobin’s
affinity for iron
d. The Bohr effect is an increase in pH and decrease in [CO2] increases haemoglobin’s affinity for O2.
The substance with the lowest oxygen affinity is
a. Whole blood
b. Hb + CO2
c. Hb alone
d. Hb + CO2 + BPG
e. Hb + BPG
a. Whole blood
The substance with the highest oxygen affinity is
a. whole blood
b. Hb + CO2
c. Hb alone
d. Hb + CO2 + BPG
e. Hb + BPG
c. Hb alone
The effect of CO₂ and BPG on Hb oxygen binding affinity is
a. CO₂ increases it, BPG decreases it
b. both increase it
c. nothing: neither have any effect
d. both decrease it
e. CO₂ decreases it, BPG increases it
d. Both CO2 binding and BPG binding with decrease Hb affinity for O2.
What is the omst common adult haemoglobin structure?
Tetrameric structure: α2β2
What is the structure of haemoglobin at birth?
α2γ2
What is the first haemoglobin produced in the embryo?
ζ2ε2
Heme which can bind oxygen consists of
a. a pyrrole ring and Fe2+
b. an imidazole ring and Fe2+
c. a benzene ring and Fe3+
d. a benzene ring and Fe3+
e. a pyrrole ring and Fe3+
a. Haem which can bind oxygen consist of a pyrrole ring and Fe2+
Which amino acid stabilises O2 binding and destabilised CO binding in haem?
Histidine
The T state of haemoglobin
a. is structurally identical to the R state
b. is caused by oxidation of the iron in heme
c. causes the subunits to dissociate
d. has a lower affinity for oxygen than the R state
e. has a higher affinity for heme than the R state
d. The T state of haemoglobin has a lower affinity for O2 than the R state.
How is carbon dioxide mainly transported in the blood stream?
As bicarbonate in the plasma
Sickle-cell anaemia
a. is only found among people of African descent
b. causes red blood cells to stick together
c. causes haemolysis at high oxygen concentrations
d. arises due to a mutation of the α haemoglobin subunit
e. is caused by HbS aggregates
e. Sickle-cell anaemia is caused by HbS aggregates
