______of the world's human population carries an inherited variant hemoglobin gene
Biology
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______of the world's human population carries an inherited variant hemoglobin gene.
A
Option A: 75%
B
Option B: 90%
C
Option C: 25%
D
Option D: 5%
E
Option E: 50%
Hemoglobin S, the variant responsible for the misshapen red blood cells characteristic of the disease sickle-cell anemia, is potentially advantageous to heterozygotes because it confers some level of resistance to the disease _________.
A
Option A: rickets
B
Option B: polycythemia
C
Option C: cyanosis
D
Option D: malaria
E
Option E: AIDS
In sickle-cell anemia, the negatively charged glutamic acid residue is replaced by the neutral amino acid ____________.
A
Option A: adenosine
B
Option B: lysine
C
Option C: glycine
D
Option D: valine
E
Option E: tyrosine
Some abnormal hemoglobins have Hill coefficients that are ______ that of normal hemoglobin, indicating that their ability to bind oxygen cooperatively has been compromised.
A
Option A: much greater than
B
Option B: less than
C
Option C: about equal to
D
Option D: greater than
E
Option E: The correct answer cannot be determined from the information given.
During the T to R conformational shift, Fe(II) drags the F helix via a bond to the side chain of ________.
A
Option A: Leu F4
B
Option B: Leu F7
C
Option C: Leu FG3
D
Option D: His F8
E
Option E: Val FG5
The reaction of carbonic anhydrase catalyzes
A
Option A: the reduction of carbon dioxide with the concomitant consumption of protons.
B
Option B: the hydrolysis of carbamates with the concomitant consumption of protons.
C
Option C: the hydration of bicarbonate, resulting in the formation of carbonic acid.
D
Option D: the hydration of carbon dioxide, forming bicarbonate and protons.
E
Option E: the formation of carbamates with the concomitant release of protons.
Why is the decreased affinity of fetal hemoglobin for BPG advantageous?
A
Option A: Decreased BPG binding biases the fetal hemoglobin toward the R state.
B
Option B: BPG is available to bind to fetal myoglobin, helping to release O2 in fetal muscle tissue.
C
Option C: None of the above.
D
Option D: More free BPG is available to bind to adult hemoglobin, resulting in a shift to the R state.
E
Option E: With fewer BPG molecules bound there are more heme residues available for O2 binding.
BPG stands for
A
Option A: boronylphenylglutamate.
B
Option B: biphenylglycine.
C
Option C: bisphosphoglycerate.
D
Option D: betapropylglutamine.
E
Option E: bisphenylglycerol.
Which of the following statements about the symmetry model of allosterism is not true?
A
Option A: the oligomer can exist in two conformational states, which are in equilibrium.
B
Option B: the ligand can bind to a subunit in either conformation.
C
Option C: the molecular symmetry of the protein is conserved during the conformational change.
D
Option D: the protein is an oligomer of symmetrically (or pseudosymmetrically) related subunits.
E
Option E: none of the above.
The rearrangement of T state hemoglobin to the R state
A
Option A: increases the ion pairing interactions of the C-terminal amino acids.
B
Option B: opens a central cavity for BPG binding.
C
Option C: occurs in each protein subunit independently when its heme binds oxygen.
D
Option D: involves the movement of the Fe(II) into the heme plane.
E
Option E: requires the binding of at least three oxygen molecules.