In this technique the cells are lysed in alkaline conditions. The DNA in the mixture is denatured (strands separated) by disrupting the hydrogen bonds between the two strands. The large genomic DNA is subject to tangling and staying denatured when the pH is lowered during the neutralization. In other words, the strands come back together in a disordered fashion, basepairing randomly. The circular supercoiled plasmids' strands will stay relatively closely aligned and will renature correctly. Therefore, the genomic DNA will form an insoluble aggregate and the supercoiled plasmids will be left in solution. This can be followed by phenol extraction to remove proteins and other molecules. Then the DNA can be subjected to ethanol precipitation to concentrate the sample.