According to the Information Center for Sickle Cell and Thalassemic Disorders, hemoglobin bonds to oxygen molecules from the lungs and delivers them to cells throughout the body. It does this with two similar bonded proteins which are necessary for the capture and release of oxygen via a central iron atom.
The Information Center for Sickle Cell and Thalassemic Disorders explains that hemoglobin is a very important molecule which, like other proteins, is created from genetic codes in cellular DNA. Mutations in these genes are rare and often harmless, but harmful diseases can arise and even be inherited. Two diseases that arise from mutations in the hemoglobin genes are sickle cell anemia and thalassemia.