Hemoglobin

What is hemoglobin? Hemoglobin is the protein molecule in red blood cells that carries oxygen from the lungs to the body's tissues and returns carbon dioxide from the tissues produced during the metabolism of food to the lungs.

The iron contained in hemoglobin is responsible for the red color of blood. Iron is involved in hemoglobin biosynthesis. While copper assists in the conversion of iron into hemoglobin.

Low hemoglobin is referred to as being anemic.

Although anemia, or a low concentration of hemoglobin in the blood, usually is considered as a sign of iron deficiency, anemia actually may have many causes.

Some of the more common reasons are loss of blood (traumatic injury, surgery, bleeding colon cancer, parasitic infection), nutritional deficiency (vitamin B12, folate acid), bone marrow problems (replacement of bone marrow by cancer, suppression by chemotherapy drugs, kidney failure), and abnormal hemoglobin (sickle cell anemia).

Hemoglobin is a transport protein, its structure is more complicated that most protein.

One hemoglobin molecule contains four separate, each a partnership of one globin and one heme. Globin is protein, the heme is not.
Hemoglobin