Pulse chase

pulse chase
(Science: biochemistry) An experimental protocol used to determine cellular pathways, such as precursor product relationships.
A sample organism, cell or cellular organelle), is exposed for a relatively brief time to a radioactively labelled molecule, the pulse. It is then replaced with an excess of the unlabelled molecule, the chase (cold chase). The sample is then examined at various later times to determine the fate of radioactivity incorporated during the pulse.