Q: Which equation correctly describes the fractional saturation ($$\theta) of $$hemoglobin with oxygen?

$$\theta = \frac{[L]^n}{[L]^n + K_d}$$

Question 1

Which of the following best describes allosteric regulation in hemoglobin?

Accepted Answer

The binding of a ligand at one site on hemoglobin affects the binding properties of other sites on the same molecule.

Question 2

The Hill equation for hemoglobin oxygen binding is given by $$\Theta_{O_2$} = \frac{pO_2$^n}{pO_2$^n + p_{50}^n}. $$What does the Hill coefficient $$n$$ represent?

Accepted Answer

The degree of cooperativity in oxygen binding to hemoglobin.

Question 3

Which of the following statements about the T (tense) and R (relaxed) states of hemoglobin is correct?

Accepted Answer

The T state has lower affinity for oxygen and is stabilized by more ionic interactions between subunits.

Question 4

Which of the following is a homotropic effector of hemoglobin?

Accepted Answer

Oxygen ($$O_2)$$

Question 5

The Bohr effect describes how hemoglobin's oxygen affinity is affected by:

Accepted Answer

Changes in pH and $$CO_2$$ concentration

Question 6

A mutation replaces His HC3 with Asp in the β chain of hemoglobin. What is the most likely effect?

Accepted Answer

The R state is favored, increasing $$O_2$$ affinity.

Question 7

Which equation correctly describes the fractional saturation ($$	heta) of $$hemoglobin with oxygen?

Accepted Answer

$$	heta = \frac{[L]^n}{[L]^n + K_d}$$

Question 8

What is the physiological significance of BPG binding to hemoglobin?

Accepted Answer

BPG stabilizes the T state, promoting oxygen release in tissues.

Question 9

At high altitude, the concentration of BPG in red blood cells increases. What is the effect on the oxygen dissociation curve?

Accepted Answer

The curve shifts to the right, facilitating oxygen release to tissues.

Question 10

Carbon monoxide ($$CO) $$poisoning is dangerous because:

Accepted Answer

$$CO$$ binds to hemoglobin with much higher affinity than $$O_2$$, reducing the number of available $$O_2$$ binding sites.

Question 11

Which of the following best explains why fetal hemoglobin (HbF) can extract oxygen from maternal blood?

Accepted Answer

HbF binds BPG with lower affinity, resulting in higher $$O_2$$ affinity compared to adult hemoglobin.

Question 12

Which of the following is a heterotropic effector of hemoglobin?

Accepted Answer

2,3-bisphosphoglycerate (BPG)

Question 13

A patient with chronic respiratory acidosis (low blood pH) will have hemoglobin that:

Accepted Answer

Releases more $$O_2 to $$tissues due to stabilization of the T state.

Question 14

Which of the following best describes the effect of $$CO_2$$ binding to hemoglobin?

Accepted Answer

$$CO_2$$ binds to the N-terminus of hemoglobin subunits, stabilizing the T state and promoting $$O_2$$ release.

Question 15

Which of the following best explains the sigmoidal shape of the hemoglobin oxygen binding curve?

Accepted Answer

Cooperative binding of $$O_2 to $$multiple subunits.

Question 16

Which of the following changes would most likely shift the hemoglobin oxygen dissociation curve to the left?

Accepted Answer

Decreased BPG concentration.

Question 17

Which of the following is true regarding the structural changes in hemoglobin upon oxygen binding?

Accepted Answer

Oxygen binding causes the F-helix to shift, altering subunit interactions and stabilizing the R state.

Question 18

Which of the following best describes the effect of increasing pH on hemoglobin's oxygen binding curve?

Accepted Answer

The curve shifts to the left, indicating increased $$O_2$$ affinity.

Question 19

Which of the following is a direct consequence of the Bohr effect in actively respiring tissues?

Accepted Answer

Hemoglobin releases more $$O_2$$ due to lower pH and higher $$CO_2.$$

Lecture 8-9: Allosterics

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