Heme is a complex molecule that plays a crucial role in various biological processes. It consists of an iron atom held within a large, organic structure called porphyrin. Heme is essential for the function of hemoglobin, the protein in red blood cells that carries oxygen from the lungs to the rest of the body. In addition to its role in hemoglobin, heme is also involved in other proteins, such as myoglobin, which stores oxygen in muscles, and various enzymes that facilitate important chemical reactions. The presence of iron in heme allows it to bind to oxygen, making it vital for respiration and energy production in living organisms.