Description
Hemoglobin is protein in red blood cells that is made up of four chains. Each of these chains contains a compound known as heme, which in turn contains iron, which is what transports oxygen in the blood stream.
Hemoglobin is responsible for the shape of red blood cells, which usually appear like donuts but with a thin center rather than a hole. In conditions in which hemoglobin is abnormal, such as sickle cell anemia, the consequent abnormal shape of the red blood cells can lead to problems.