Given the task definition and input, reply with output. Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

Question: In a model of a hemoglobin molecule, the purple part indicates the presence of what element? Answer: iron
Hemoglobin Molecule. This model represents the protein hemoglobin. The purple part of the molecule contains iron. The iron binds with oxygen molecules.