The pigment molecule that transports oxygen in the red blood cells of humans is called .

The pigment molecule that transports oxygen in the red blood cells of humans is called hemoglobin. Hemoglobin is a complex protein made up of four subunits, each containing an iron atom within a heme group. This structure allows hemoglobin to bind to oxygen efficiently in the lungs and release it in the tissues where it is needed. In addition to its primary role in oxygen transport, hemoglobin also plays a crucial part in the transport of carbon dioxide, a waste product of metabolism, from the tissues back to the lungs for exhalation. The ability of hemoglobin to pick up and release these gases is essential for maintaining the body’s respiratory and metabolic functions.