During the purification process for recombinant DNA technology, addition of chilled ethanol precipitates out:

During the isolation of genetic material, DNA is released from the cell along with other macromolecules like RNA, proteins, and lipids. After treating the mixture with enzymes like protease and RNase to remove impurities, chilled ethanol is added. Since DNA is insoluble in ethanol, it precipitates out as a collection of fine threads in the suspension.