Which of the following is false a The release of oxygen from

Which of the following is false?

a. The release of oxygen from the R form of hemoglobin in red blood cells is more pronounced than in pure hemoglobin as the concentration of oxygen decreases.

b. In the presence of 2,3-bisphosphoglycerate, the affinity for oxygen in fetal hemoglobin is higher than maternal hemoglobin

c. Myoglobin does not use an allosteric effect

d. Hydrogen ions and carbon dioxide will help increase the release of oxygen from the R form of hemoglobin in the tissue.

e. None of the above

Solution

Answer:

a. The release of oxygen from the R form of hemoglobin in red blood cells is more pronounced than in pure hemoglobin as the concentration of oxygen decreases.

False

he R-state, or relaxed state occurs when hemoglobin has bound to oxygen. Deoxyhemoglobin, or the T-state, has a low affinity for oxygen. When one molecule binds to a single heme, though, the oxygen affinity increases, which allows the following molecules to bind more easily in succession.

b. In the presence of 2,3-bisphosphoglycerate, the affinity for oxygen in fetal hemoglobin is higher than maternal hemoglobin.

True

In adult red blood cells,   2,3-bisphosphoglycerate (BPG) decreases the affinity of hemoglobin for oxygen. But in fetus, due to lack of fetal hemoglobin\'s interaction with 2,3-bisphosphoglycerate, the fetal haemoglobin has greater affinity for oxygen. That means, the presence of BPG has no role on affinty of fetal haemoglobin for oxygen.

c. Myoglobin does not use an allosteric effect

True

Comparison of the oxygen binding properties of myoglobin and hemoglobin illustrate the allosteric properties of hemoglobin that results from its quaternary structure and differentiate hemoglobin\'s oxygen binding properties from that of myoglobin. The curve of oxygen binding to hemoglobin is sigmoidal typical of allosteric proteins in which the substrate, in this case oxygen, is a positive homotropic effector. In contrast the oxygen binding curve for myoglobin is hyperbolic in character indicating the absence of allosteric interactions in this process.

d. Hydrogen ions and carbon dioxide will help increase the release of oxygen from the R form of hemoglobin in the tissue.

True

The more presence of hydrogen ion and carbon dioxide, decreases the pH value towards somewhat acidic at tissue surfaces. At lower pH, the R form of haemoglobin release oxygen and become T form.