Dot blot is the technique for measuring the amount of one perticular DNA or RNA in the highly complex mixture. The samples are spotted onto the hybridization membrane (like nitrocellulose or activated nylon, and many more), fixed and hybridized with the radioactive search. The extent of labeling (as determined by autoradiography and the densitometry) is proportional to concentration of the target molecule in its sample. Standards give the means of calibrating the results.