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Quiz 7
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Questions in this quiz (25)
1roof for distinct T and R hemoglobin came from experiments involving-
- AX-ray diffraction studies
- Boxygen binding experiments
- Cdetermination of molecular weight of hemoglobin subunits
- Dexperiments with carbon monoxide
2The physiological increase in the blood level of BPG is an adaptation to higher elevation because
- AA More hemoglobin will stay in the R state
- BB PBG increases the affinity of hemoglobin to O2
- CC Hemoglobin has a reduced capacity to carry O2
- DD Hemoglobin's ability to bind O2 near the lungs remains virtually unchanged
- EA and B
- FC and D
3In the concerted mode for cooperatively, the hemoglobin subunits --
- Abing or release oxygen, all at ocne
- Bshow maximum cooperatively when no BPG is present
- Cbinds to oxygen in order, first the two alpha subunits, then the two beta subunits.
- Dchante T to R or vice versa
4The prosthetic group attached to hemoglobin is
- AA part of its secondary structure
- Ba substrate of hemoglobin
- Ca ligand of hemoglobin
- Dhydrogen bounded to hemoglobin
- Epermanently associated with hemoglobin
5Which of the following properties is shared by both myoglobin and hemoglobin?
- AIf one has a point mutation from Glu to Val, they both have the ability to cause sickle cell anemia
- BThey are both allosteric proteins
- CThey both bind BPG
- DThey will both bind more O2 where it is more abundant, release O2 where it is more scarce
- EAll of the above are shared.
6Myoglobin and Hemoglobin share the following properties EXCEPT
- AThey have both have a heme prosthetic group that binds oxygen
- BThey are both oxygen carrier proteins
- CThey are both located in blood's red cells
- Dtheir polypeptide structures are many alpha helices
- Ethey share a common evolutionary linkage
7In a fetus, hemoglobin has gamma chains instead of beta chains. One difference is less positive charges in the central cavity of hemoglobin. This increase in the affinity of hemoglobin to oxygen because
- ABPG binds less tightly
- BIt allows BPG to bind more tightly
- CIt creates less electrostatic repulsion between the subunits of Hemoglobin
- DAll of the above
8Which expression is the fraction of oxygen bound myoglobin in solution (theta, or Y)?
- A[MbO2]/[Mb][O2]
- B[Mb][O2]/[MbO2]
- C[Mb]+[MbO2]
- DpO2/pO2 + p50
9When the dissociation constant (Kd) of any ligand is smaller by comparison, it means
- Athe ligand binds with lower affinity
- Bthe ligand binds with higher affinity
- Cthe concentration of the ligand has decreased
- Dthe concentration of the ligand has increased
10The binding of one or more O2 ligands to molecule of hemoglobin will induce:
- Athe release of any other O2 that may have bound earlier.
- BA decrease in hemoglobin's ability to bind a second O2
- Cdissociation of the hemoglobin subunits
- Dthe movement of hemoglobin to an organism's muscle tissue
- Ean increased affinity for O2 in the remaining subunits (which have not yet bound O2)
11When moving towards the lungs, hemoglobin shifts to the ___ conformation, in which the Kd for oxygen binding is _____.
- AR; increased
- BT; lowered
- CR; lowered
- DT; increased
12When red blood cells migrate away from the lungs, initial oxygen dissociation from hemoglobin is stimulated by _____ and further on, dissociation is enhanced by _____.
- ABPG; lower [oxygen]
- Blower [oxygen]; lower [oxygen]
- CBPG; T/R transition
- Dlower [oxygen]; T/R transition
13Which of the following is NOT correct concerning 2,3-bisphosphoglycerate (BPG)?
- AIt binds at a distance from the heme groups of hemoglobin.
- BIt binds with lower affinity to fetal hemoglobin than to adult hemoglobin
- CIt is an allosteric modulator
- DIt is normally found associated with hemoglobin extracted from red blood cells
- EIt increases the affinity of hemoglobin for oxygen.
14The initial trigger for conformational change in hemoglobin, leading to T/R transition, involves
- Adramatic change in the affinity to oxygen in all four binding sites
- Bshift in the relative position of the alpha and beta subunits
- Cshift in the porphyrins plane upon oxygen binding, from concave to planar
- DAll of the above
15The Hills coefficient
- Ais greater for myoglobin than it is for hemoglobin
- Brepresents the total number of ligand bonding sites in the proteins
- Cis larger when cooperatively is larger
- Dis the difference in fraction bound to hemoglobin between lungs and capillaries
16Protection from low levels of CO poisoning is in part due to the fact that
- Athe binding configuration of CO to heme iron favors oxygen binding.
- Bthe His F8 on hemoglobin distorts the heme iron atom out of the heme plane and attracts O2, but not CO.
- CThe affinity of heme for O2 is much greater than for CO
- DThe CO cannot bind to heme in hemoglobin
- EAll of the above.
17In the binding of oxygen to myoglobin, the relationship between the concentration of oxygen and the fraction of binding sites occupied can best be described as
- Ahyperbolic
- Bsigmoidal
- Clinear with positive slope
- Dlinear with negative slope
- Enonrandom
18Le Chattier principle predicts that
- Aoxygen will dissociate from hemoglobin where blood oxygen is high
- Boxygen will dissociate from hemoglobin where blood oxygen is low
- Coxygen binding to hemoglobin is independent of blood oxygen levels
- Doxygen binding too hemoglobin is independent of blood oxygen levels
- Eoxygen will only bind to hemoglobin in R state
- Foxygen will only bind to hemoglobin in T state
19When a ligand binds with a protein
- AIt is relatively non-specific
- BIt is usually irreversible.
- CIt is usually short lived
- DIt is usually the result of the inactivation of the proteins
- Eit is rare in biological systems.
20The hypothesis that hemoglobin shifts between a low and a high affinity form implies that the protein-
- Ahas a prosthetic group
- Bhas two binding sites for oxygen
- Cexists in two distinct conformations
- Dis coded by two different genes
- Enone of the above
21BPG binding to hemoglobin requires that:
- Athe protein will be in the R state
- BThe protein will be in the T state
- CThe red blood cells will be as close as possible to the lungs
- DThe protein will have oxygen dissociated from all its for heme groups.
- EThe protein can be in either R or T state.
22Which of the following is the major form of hemoglobin produced in RBCs during normal adult life?
- Azeta2/epsilon2
- Balpha2/gamma2
- Calpha2/beta2
- Dalpha2/delta2
- Ealpha2/epsilon2
23In sickle cell anemia, the gene coding for the beta-chain of hemoglobin shows
- Aa missense mutation leading to the formation of a shortened polypeptide
- Ba missense mutation leading to elimination of the heme prosthetic group, where oxygen binds
- Ca missense mutation leading to the substitution of glu to val
- DA missense mutation leading to the elimination of the central cavity of hemoglobin
24When O2 binds to heme in hemoglobin, the _____ is drawn into the plane of the porphyrin, causing a conformational change that is transmitted to adjacent subunits, ________ the affinity for additional O2 binding.
Select one:- AHistidine E7; lowering
- BFe2 atom; decreasing
- CHistidine E7; increasing
- DFe2 atom; increasing
25In myoglobin's binding surge, the dissociation constant Kd is
- A[Mb][O2]/[MbO2]
- BpO2/pO2+p50
- C[Mb]+[MbO2]
- D[MbO2]/[Mb][O2]
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- Quiz on Quiz 7, created by genny stubbs on 14/06/2017.
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- genny stubbs
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- Created on 14 Jun 2017 · updated on 14 Jun 2017
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