1.Starting from the O2 binding equilibrium of human hemoglobin written below, derive theHbnO22 Hb(O2)n+equation underlying the Hill plot. Draw a generic Hill plot and indicate at what O2 saturation conditionsthe equilibrium dissociation constants (Kd, K1, K4) are defined by the plot. Also, show how the valuesof the Hill coefficient are determined at 50% saturation and at their asymptotic limits. Explain theinterpretation of the value of the Hill coefficient nH at 50% saturation compared to the total number ofsubunits in the allosteric molecule.

Fractional saturation 'Y' can be written as; Y= [L]n[L]n + Kd ' here 'L' is O2 .…

Answered: Starting from the O2 binding…

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter46: Gas Exchange: The Respiratory System

Section: Chapter Questions

Problem 9TYK

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Under appropriate conditions, hemoglobin dissociates into its four subunits. The isolated α subunit binds oxygen, but the O2 -saturation curve ishyperbolic rather than sigmoid. In addition, the binding of oxygen to the isolated α subunit is not affected by the presence of H+, CO2 , or BPG. What do these observations indicate about the source of the cooperativity in hemoglobin?
Studies of oxygen transport in pregnant mammals show that the O2-saturation curves of fetal and maternal blood are markedly different when measured under the same conditions. Fetal erythrocytes contain astructural variant of hemoglobin, HbF, consisting of two α and two γ subunits (α2 γ2 ), whereas maternal erythrocytes contain HbA (α2β2).(a) Which hemoglobin has a higher affinity for oxygen under physiological conditions, HbA or HbF? Explain.(b) What is the physiological significance of the different O2 affinities?(c) When all the BPG is carefully removed from samples of HbA and HbF, the measured O2 -saturation curves (and consequently the O2 affinities) are displaced to the left. However, HbA now has a greater affinity for oxygen than does HbF. When BPG is reintroduced, the O2 -saturation curves return to normal, as shown in the graph. What is the effect of BPG on the O2 affinity of hemoglobin? How can the above information be used to explain the different O2 affinities of fetal and…
Studies of oxygen transport in pregnant mammals have shown that the O2-saturation curves of fetal and maternal blood are markedly different when measured under the same conditions. Fetal erythrocytes contain a structural variant of hemoglobin, HbF, consisting of two γ and two β subunits (γ2β2), whereas maternal erythrocytes contain HbA (α2β2). (a) Which hemoglobin has a higher affinity for oxygen under physiological conditions, HbA or HbF? Explain. (b) What is the physiological significance of the different O2 affinities? (c) When all the BPG is carefully removed from samples of HbA and HbF, the measured O2-saturation curves (and consequently the O2 affinities) are displaced to the left. However, HbA now has a greater affinity for oxygen than does HbF. When BPG is reintroduced, the O2-saturation curves return to normal, as shown in the graph. What is the effect of BPG on the O2 affinity of hemoglobin? How can the above information be used to explain the different O2 affinities of…
3. When muscles are more active physiological conditions change to affect oxygen binding to Hemoglobin. Briefly describe the changes that occur and why this affects hemoglobin function. Draw the shifted curve on the graph above. A. What physiological conditions change during exercise (levels of what molecules are increasing/decreasing)? B. How do these molecules directly affect Hb’s structure ? What interactions does this stabilize ? C. How do these interactions affect the affinity of Hb for O2? How would this affect the binding curve for Hb? Draw on the graph provided. D. How will this shift in the binding curve affect the function of Hemoglobin ? E.Where does the physiological pO2 in the tissues fall on the O2 binding curve ? In the lungs ? Why is this physiologically important?
A new oxygen transport protein that exhibits cooperative binding has been isolated and is beingstudied in the lab. Calculate the KD value if Y = 0.76 when pO2 = 18 torr (assume n = 2.5). Howdoes this compare to the KD value for hemoglobin? Does this protein bind more or less tightly tooxygen compared to hemoglobin?
a) How does the fetal hemoglobin differ from the maternal hemoglobin in regards to structure and function? b) Explain the Bohr effect by drawing oxygen dissociation curves on a single graph that highlight changes in the hemoglobin affinity for O2 c) Describe the molecular basis of sickle cell anemia. Be specific
The 2-3 phosphoglycerate (BFG) binds to the central gap formed by the hemoglobin monomers (a2b2) facilitating the reversible release of oxygen. Approximate relationships between BFG concentrations in red blood cells and Pos in hemoglobin are in the table.a) Draw the reaction schemeb) Write the forces that condition the union between hemoglobin and BFG
The hemoglobin of a human fetus differs from adult hemoglobin. Compare the dissociation curves of the two hemoglobins in the graph at right. Describe how they differ, and propose a hypothesis to explain the benefit of this difference.
The equation describing the linear relationship between hemoglobin concentration and absorbance at 520 nm is y=0.0523x+0.011. If the absorbance value is 0.6, calculate the % hemoglobin in whole blood.
Increasing concentrations of either 2,3-bisphosphoglycerate (BPG) or protons (H +) cause a ____________ ( rightward OR leftward) shift of the hemoglobin/oxygen binding curve. However, the mechanisms by which these two substances mediate this effect are distinct. Compare & contrast the way by which BPG and protons interact with hemoglobin and thereby influence its structure and function
Comparison of Fetal and Maternal Hemoglobins.Studies of oxygen transport in pregnant mammals show that the O2-saturation curves of fetal and maternal blood are markedly different when measured under the same conditions. Fetal erythrocytes contain a structural variant of hemoglobin, HbF, consisting oftwo a and two g subunits (α2γ2), whereas maternal erythrocytes contain HbA (α2β2). a)Which hemoglobin has a higher affinity for oxygen under physiological conditions, HbA or HbF? Explain. b)What is the physiological significance of the different O2 affinities? c)When all the BPG is carefully removed from samples of HbA and HbF, the measured O2-saturation curves (and consequently the O2affinities) are displaced to the left. However, HbA now has a greater affinity for oxygen than does HbF. When BPG is reintroduced, the O2-saturation curves return to normal, as shown in the graph. What is the effect of BPG on the O2affinity of hemoglobin? How can the above information be used…
Sixty hours after aspirin ingestion, the patient’s blood pH has returned to normal (pH7.4). Describe how the carbonic acid/bicarbonate buffering system responded to bring thepatient’s blood pH back to normal. LeChatelier’s Principle may be helpful here. For the question above, doesn't the stopping of hyperventilation (due to the passage of time) automatically increase the CO2 concentration in blood, thus re-establishing all the "normal" equilibria, including the one with H+? How does the H2CO3/HCO3- buffer respond?

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