Abstract: The invention provides a method and kit for the separation and purification of cellular components including polar and non-polar metabolites, genomic DNA, RNA and proteins from a single biological sample where two steps of lysis of the cells are performed sequentially, before and after a metabolite isolation step. The first lysis step is mechanical and performed in order to be incomplete, whereas the second is chemical or both mechanical and chemical. A sequential isolation of genomic DNA, RNA and proteins is carried out after the second lysis step.