Why use radioisotopes in research?
The most important use of radioisotopes in bio-medical research is to label compounds so that quantities too small for chemical analysis can be traced through biological processes. While fluorescent tags might also be used, these tags alter the structure of the substance being studied which raises the question of whether or not that substance (with its fluorescent tag) will act identically to the substance without the tag. By using radioactive isotopes to directly replace non-radioactive atoms, the biology of the substance is not altered.
