<P> The blood 's red color is due to the spectral properties of the hemic iron ions in hemoglobin . Each human red blood cell contains approximately 270 million of these hemoglobin molecules . Each hemoglobin molecule carries four heme groups ; hemoglobin constitutes about a third of the total cell volume . Hemoglobin is responsible for the transport of more than 98 % of the oxygen in the body ( the remaining oxygen is carried dissolved in the blood plasma ) . The red blood cells of an average adult human male store collectively about 2.5 grams of iron , representing about 65 % of the total iron contained in the body . </P>
<P> The blood 's red color is due to the spectral properties of the hemic iron ions in hemoglobin . Each human red blood cell contains approximately 270 million of these hemoglobin molecules . Each hemoglobin molecule carries four heme groups ; hemoglobin constitutes about a third of the total cell volume . Hemoglobin is responsible for the transport of more than 98 % of the oxygen in the body ( the remaining oxygen is carried dissolved in the blood plasma ) . The red blood cells of an average adult human male store collectively about 2.5 grams of iron , representing about 65 % of the total iron contained in the body . </P>
number of hemoglobin molecules in a red blood cell
number of hemoglobin molecules in a red blood cell
approximately 270 million
approximately 270 million