Biomedical Engineer Question:

This technique is used to understand chemical reaction and interactions in bio-chemistry and chemistry. In this technique, one or more of the atoms of the molecule of interest is substituted for an atom of the same chemical element, but that element belongs to different isotope. It can be used to detect the difference in number of neutrons separately from the other atoms of the same element. The atom has the same number of protons; it will behave in almost exactly the same way chemically as other atoms in the compound, and with few exceptions will not interfere with the reaction under investigation.