Animation - Hemoglobin Breakdown

Why is the processing of hemoglobin different from the processing of many other macromolecules?

Hemoglobin contains a heme group with contains iron. The heme group is used to bind oxygen. Iron is not used in most other types of macromolecules and is not common in biological systems. Conservation of iron is important as any iron lost will need to be replaced from the diet. Therefore the heme group is processed independently from the rest of the hemoglobin molecule in order to ensure conservation of iron to build more hemoglobin.

<a rel="nofollow" href="https://http://glencoe.mcgraw-hill.com/sites/dl/free/9834092339/291136/HemoglbnBrkdown.swf" target="_blank">https://http://glencoe.mcgraw-hill.com/sites/dl/free/9834092339/291136/HemoglbnBrkdown.swf</a>