What are the main components of hemoglobin?

The main components of hemoglobin consist of four heme groups, four iron atoms, and four globin chains. Each heme group contains an iron atom capable of binding oxygen, allowing red blood cells to transport oxygen from the lungs to tissues throughout the body. The four globin chains, typically comprising two alpha and two beta chains in adult hemoglobin, provide structural integrity and help in the proper function of hemoglobin.

In adult humans, hemoglobin's quaternary structure features these four heme groups, and each one of these groups binds to an iron atom. Therefore, with a total of four heme groups and four iron atoms, the configuration allows each hemoglobin molecule to carry up to four molecules of oxygen.

Understanding this accurate makeup is crucial for comprehending hemoglobin function in oxygen transport and its overall role in physiology. The choice with two heme, or a different number of globins or iron, does not reflect the accurate molecular structure of hemoglobin, which is why they do not meet the criteria for the correct composition.