Final answer:
Each hemoglobin molecule contains four iron atoms, bound within the heme groups of the molecule's four globin proteins. This enables hemoglobin to carry up to four oxygen molecules, critical for blood oxygenation.
Step-by-step explanation:
Each hemoglobin molecule contains four iron atoms. These atoms are integral to the molecule's functionality. Hemoglobin is comprised of four globin proteins, each of which is bound to a heme group that contains one of these iron ions. The two types of globin proteins are known as alpha (alpha 1 and alpha 2) and beta (beta 1 and beta 2) chains. As a result, the correct answer to the question is that each hemoglobin molecule contains C) four iron atoms.
Each heme group within the hemoglobin structure can bind to one oxygen molecule, allowing a single hemoglobin molecule to transport up to four oxygen molecules. This efficient transport mechanism is responsible for the oxygenation of blood, with oxygen-rich blood being bright red, while oxygen-depleted blood, such as venous blood, is a darker shade of red.