Since, the DNA is enclosed within the membranes, we have to break the cell open to
release DNA along with other macromolecules such as RNA, proteins, polysaccharides
and also lipids.


This can be achieved by treating the bacterial celis/plant of animal tissue with enzymes
such as lysozyme (bacteria), cellulase (plant cells) and chitinase (fungus).

As we know that genes are located on long molecules of DNA interwined with proteins
such as histones. The RNA can be removed by treatment with ribonuclease, whereas
proteins can be removed by treatment with protease.

Other molecules can be removed by appropriate treatments and purified DNA
ultimately precipitates out after the addition of chilled ethanol. Deoxyribonuclease is not
used in this process as this enzyme causes the lysis of DNA molecules.