The iron that binds oxygen in hemoglobin is located in which part of the molecule?

The iron that binds oxygen in hemoglobin is located in which part of the molecule?

• A. Globin
• B. Plasma
• C. Heme
• D. Platelets

Answer: (C)

The iron that binds oxygen is located in the heme group, the iron-containing prosthetic component tucked inside each globin chain of hemoglobin. Each of the four heme units has an iron ion (Fe2+) at its center that reversibly binds O2 as blood passes through the lungs and tissues. The surrounding globin protein provides the pocket and environment that position the heme correctly and influence binding, but the actual binding site for oxygen is the iron within the heme. The other options—globin, plasma, and platelets—don’t contain the iron-oxygen binding center.

The iron that binds oxygen is located in the heme group, the iron-containing prosthetic component tucked inside each globin chain of hemoglobin. Each of the four heme units has an iron ion (Fe2+) at its center that reversibly binds O2 as blood passes through the lungs and tissues. The surrounding globin protein provides the pocket and environment that position the heme correctly and influence binding, but the actual binding site for oxygen is the iron within the heme. The other options—globin, plasma, and platelets—don’t contain the iron-oxygen binding center.