Q. 16.54 - An Introduction to General, Organic, and Biological Chemistry

Question

Fetal hemoglobin binds oxygen more tightly than does adult hemoglobin. Why do you think fetal hemoglobin functions differently than adult hemoglobin?

Step-by-Step Solution

Answer

Fetal hemoglobin is produced by the fetus in the uterus and has a higher affinity for oxygen, but it is replaced by adult hemoglobin after about $6$ months. 

Step1: Introduction.

Sickle cell anemia is a genetic disorder in which a mutation in the $DNA$ changes the amino acid in the protein, affecting the protein structure. 

As a result, hemoglobin's structure changes from round to sickle cell, destroying its ability to transport oxygen. 

Step2: Given Information.

Adult hemoglobin binds oxygen less tightly than fetal hemoglobin.

Reason to believe that fetal hemoglobin works differently than adult hemoglobin.

Step3: Explanation.

Fetal hemoglobin is produced by the fetus in the uterus and has a higher affinity for oxygen, but it is replaced by adult hemoglobin after about $6$ months. 

The glycolytic intermediate $2,3-$bisphosphoglyceric acid $(2,3 BPG)$ is found in human red blood cells.

$2,3-$$BPG$ has an affinity for deoxygenated hemoglobin, and when bound to hemoglobin, it reduces hemoglobin's affinity for oxygen.

Fetal hemoglobin has a lower affinity for $2,3-BPG$, resulting in a higher affinity for oxygen.