Questions & Answers

Hemoglobin contains
A. $F{e^{2 + }}$
B. $M{g^{2 + }}$
C. $N{a^{2 + }}$
D. $C{a^{2 + }}$

Answer Verified Verified
Red blood cells (RBCs), also known as erythrocytes, are important cells that make up the majority of the blood volume. They are enucleated and disc-shaped to perform an important function to transport oxygen. This function is accomplished because of hemoglobin. Hemoglobin is a special protein found in the RBC which functions to transport oxygen.

Complete answer:
To solve this question, we must understand the structure and function of hemoglobin.
Hemoglobin is an iron-containing protein involved in oxygen transport. It is also spelled as haemoglobin. In an oxygenated state, it is called oxyhemoglobin and hemoglobin without oxygen is deoxyhemoglobin.
Hemoglobin has a stronger affinity for carbon-monoxide and forms carboxyhemoglobin. Thus in presence of carbon-monoxide it binds to it, leading to death of the individual.
Carbaminohemoglobin is hemoglobin with carbon-dioxide.
Hemoglobin consists of heme and globin. Heme contains iron and protoporphyrin. Globin is the protein component. Globin is a water soluble protein, and forms colloids in water.
It has four iron atoms and thus four sites to bind to oxygen. Thus, each hemoglobin can bind to four oxygen molecules. It binds to the heme portion. Iron exists in ferrous form ($F{e^{2 + }}$).
Hemoglobin is structurally made of four heme groups that surround globin protein. It has a tertiary structure.
Heme is synthesized in the mitochondria and cytosol of immature RBC. The globin protein is synthesized in the ribosome. The subunits present in hemoglobin are α and β subunits.
Hemoglobin exists in different forms. The most common is HbA found in adults, which has 2 $\alpha $ subunits and 2 $\beta $ subunits. It is a heterotetramer.
In the case of people with sickle cell anemia, hemoglobin is represented as HbS. It is defective and unable to bind oxygen.

Thus, the correct answer is option A- $F{e^{2 + }}$ .

Note: If iron is present in $F{e^{3 + }}$ state, then it is Methemoglobin (MetHb). Methemoglobinemia is a blood disorder in which an abnormal amount of MetHb is produced. This hemoglobin can carry oxygen but is unable to release it at tissues. It is a genetic condition.