Hemoglobin is primarily categorized as what type of biological molecule?

Hemoglobin is primarily categorized as a protein because it is composed of long chains of amino acids that are folded into a specific three-dimensional structure. Proteins serve various functions in the body, including serving as enzymes, structural components, and transport molecules. Hemoglobin specifically plays a crucial role in transporting oxygen in the blood from the lungs to the rest of the body, as well as transporting carbon dioxide back to the lungs for exhalation. The unique structure of hemoglobin, including its heme groups that bind oxygen, is a hallmark of protein molecules. This classification underscores the importance of proteins in biological systems and highlights how they can be tailored to perform specific physiological functions.