Q: Which structural difference allows fetal hemoglobin (HbF) to have a higher affinity for oxygen compared to adult hemoglobin (HbA)?

HbF contains gamma ($ \gamma $) subunits instead of beta ($ \beta $) subunits.

Question 1

Which structural difference allows fetal hemoglobin (HbF) to have a higher affinity for oxygen compared to adult hemoglobin (HbA)?

Accepted Answer

HbF contains gamma ($ \gamma $) subunits instead of beta ($ \beta $) subunits.

Question 2

What is the primary reason fetal hemoglobin (HbF) can extract oxygen from maternal blood in the placenta?

Accepted Answer

HbF has a lower affinity for 2,3-BPG, resulting in a higher affinity for O$_2$.

Question 3

Given the dissociation constant (K$_d$) values for two hemoglobins, which hemoglobin has a stronger affinity for O$_2$?

Accepted Answer

The hemoglobin with the lower K$_d$ value.

Question 4

2,3-Bisphosphoglycerate (2,3-BPG) binds to hemoglobin and decreases its affinity for O$_2$. Which of the following best explains why this is physiologically important?

Accepted Answer

It facilitates the release of O$_2$ from hemoglobin in peripheral tissues.

Question 5

Which of the following best describes the effect of 2,3-BPG on the oxygen dissociation curve of adult hemoglobin?

Accepted Answer

It shifts the curve to the right, promoting O$_2$ release.

Question 6

A patient with a genetic mutation resulting in decreased 2,3-BPG production would likely experience which of the following?

Accepted Answer

Reduced O$_2$ delivery to peripheral tissues.

Question 7

Why does fetal hemoglobin (HbF) bind 2,3-BPG less effectively than adult hemoglobin (HbA)?

Accepted Answer

HbF lacks the specific amino acid residues required for 2,3-BPG binding.

Question 8

Which of the following statements best explains why 2,3-BPG is important during exercise?

Accepted Answer

2,3-BPG increases in red blood cells, enhancing O$_2$ release to active muscles.

Question 9

Which of the following best describes the Bohr effect in hemoglobin?

Accepted Answer

A decrease in pH (increase in H$^+$) reduces hemoglobin's affinity for O$_2$.

Question 10

A researcher is comparing the oxygen dissociation curves of HbA and HbF. Which of the following would she observe?

Accepted Answer

The HbF curve is shifted to the left of the HbA curve.

Question 11

Which of the following is a direct consequence of 2,3-BPG binding to hemoglobin?

Accepted Answer

Stabilization of the T (tense) state of hemoglobin.

Question 12

If a mutation increased the affinity of adult hemoglobin for 2,3-BPG, what would be the expected physiological outcome?

Accepted Answer

Decreased O$_2$ affinity and increased O$_2$ delivery to tissues.

Question 13

Which of the following best explains why 2,3-BPG is not bound by myoglobin?

Accepted Answer

Myoglobin is a monomer and lacks the central cavity present in hemoglobin.

Question 14

A patient with chronic hypoxia is found to have elevated levels of 2,3-BPG. What is the physiological significance of this adaptation?

Accepted Answer

It promotes O$_2$ release from hemoglobin to compensate for low O$_2$ availability.

Question 15

Which of the following would most likely occur if 2,3-BPG were completely absent from adult red blood cells?

Accepted Answer

Hemoglobin would bind O$_2$ too tightly, impairing O$_2$ delivery to tissues.

Fetal Hemoglobin and Oxygen Affinity: Biochemical Mechanisms

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