Final answer:
Oxygen is attached to an iron atom located on the heme portion of hemoglobin, which is a protein essential for oxygen transport in the blood.
Step-by-step explanation:
Oxygen is attached to an iron atom located on the heme portion of hemoglobin. Hemoglobin is a protein in red blood cells responsible for transporting oxygen from the lungs to the rest of the body and returning carbon dioxide to the lungs for exhalation.
The heme group in hemoglobin consists of an iron atom (Fe²⁺) that can bind to oxygen. Each molecule of hemoglobin contains four such heme groups, allowing for the transport of multiple oxygen molecules. Importantly, the ability for hemoglobin to carry oxygen relies on the iron being in the ferrous (Fe²⁺) state; oxidation to the ferric (Fe³⁺) state prevents oxygen binding, thus affecting the oxygen transport capacity.
The structure of heme is crucial for the function of hemoglobin, resembling that found in chlorophyll, but with a key difference in the metal ion present. In plants, chlorophyll contains magnesium instead of iron. The presence of iron in hemoglobin is also what gives blood its characteristic red color, which changes to a bluish red when deoxygenated.