Cesium is used in the separation of DNA with different densities. Cesium chloride (CsCl) acts as a density gradient for the separation of the DNA (Deoxy ribonucleic acid), and is used in gradient centrifugation.
CsCl density centrifugation:
CaCl solution is kept in the centrifuge tube along with the DNA sample to be separated.
The centrifugation causes the solutions to form bands with the denser part at the bottom and the least denser part at the top.
The DNA with its density similar to a particular layer of CsCl solution density forms a band in that layer.