Final answer:
Hemoglobin binds to oxygen, carbon dioxide, and hydrogen ions (protons) to facilitate transport through the blood. Bicarbonate ions are indirectly related to hemoglobin's function but are not bound directly to it.
Step-by-step explanation:
Hemoglobin, the oxygen-transporting metaloprotein in red blood cells, can carry several substances through the blood. Specifically, hemoglobin can bind to oxygen, carbon dioxide, and hydrogen ions (protons). Although it does not directly bind bicarbonate ions, it plays an indirect role in their formation and transport in the blood.
Oxygen molecules bind to the iron-containing heme groups within hemoglobin, a process essential for transporting oxygen to body tissues. Carbon dioxide transport occurs through three methods in the blood: dissolution directly into the blood, as bicarbonate ions via the bicarbonate system, and by binding to hemoglobin to form carbaminohemoglobin. This binding is reversible, allowing carbon dioxide to be released into the lungs and exhaled. Hemoglobin also helps in pH regulation by binding hydrogen ions, which are generated during the conversion of carbon dioxide into bicarbonate in red blood cells.