Antibodies are important.tools for detecting and localising specific molecules in the cells due to their high specificity. The first requirement for this is to produce antibodies against a specific molecule. Suppose you want to produce antibodies against tubulin, the purified tubulin is first obtained from a given tissue. It is then injected into an animal such as rabbit which in nwse to tubulin produces antibodies. Blood sample is collected from the animal and antibodies are isolated. These antibodies are used to locakise the specific molecule in the cell because they bind only 80 an antigen, which is a tubulia in this case. Localisation can be done by two methods: direct and inditect In the direct method, antibodies are first labelled with a flouroscendt dye-like rhodamide for light microscopy, or witha high molecular weight, electron dense compound like ferritin for transmission electron microscopy. Fluorescent labelled antibodies are allowed to react with cells so as to form systematic antibody complex. The complex is then examined undera microscope (fluorescent microscope or TEM). The specific molecules will emit light or become electron dense due to their binding with labelled antibodies (Figure shown below). This method is used to locdise foreign bodies such us viruses, bacterial antigevs, etc.