Final answer:
The protein responsible for binding and transporting oxygen in the bloodstream is hemoglobin, which contains iron. Hemoglobin is made of four subunits, each with a central iron ion that binds oxygen, and this function is essential for transporting oxygen to body cells and carbon dioxide to the lungs.
Step-by-step explanation:
The protein that binds oxygen for transport in the bloodstream, which is a necessary component of red blood cells, is hemoglobin. This complex protein is responsible for carrying oxygen to cells and removing carbon dioxide to the lungs. Hemoglobin is composed of four symmetrical subunits and four heme groups, each containing one atom of the essential trace mineral iron.
Within the heme group, the iron ion plays a crucial role, as it binds to oxygen when red blood cells pass through the pulmonary capillaries. This binding occurs when the iron in the heme group's oxidation state changes from +2 to +3 as oxygen attaches, altering the three-dimensional structure of hemoglobin. As blood reaches tissues requiring oxygen, iron releases the bound oxygen, allowing it to diffuse into the body's cells.
Iron's importance extends beyond just hemoglobin. The iron absorbed from food contributes to the body's total iron pool, stored in compounds like ferritin and hemosiderin within the bone marrow, liver, and spleen. During erythrocyte production, stimulated by the hormone EPO, iron is released from storage, binds to transferrin, and is carried to the red marrow to become part of new red blood cells.
The presence of iron in blood not only facilitates oxygen transport but also gives blood its characteristic red color. Without this essential element, the critical function of oxygen transportation by hemoglobin would not be possible, signifying iron's vital role in our body's physiology and health.