Each of the protein chains are conjugated to a nonprotein group.

Each of the protein chains are conjugated to a nonprotein heme group.Hemoglobin is the protein that's made of the four polypeptide chains. Each of these chains contains a heme group. Red blood cells are primary players in the oxygen hauling, and they wouldn't be able to do their job if it the weren't for a special molecule called the heme.

Cells of an organism tell each other when predators are near.