(i) In prokaryotes, the bacterial cells are treated with certain lysozymes to break the cell wall. (ii) In eukaryotes plant cell wall can be removed by treatment with cellulase; in case of fungi, it can be removed by treatment with chitinase. Common steps of prokaryotes and eukaryotes: After the boundary is broken, the nucleic acid (along with other compounds) is released from the cell. The DNA exists with certain proteins and RNA; so they have to be removed. Proteins are removed by treatment with proteases and RNA by treatment with ribonuclease. Other molecules are removed by appropriated treatment. Then DNA is precipitated out after the addition of chilled ethanol.