Lysis, or breaking open the cells, is the first step of DNA extraction. This is accomplished by a buffer containing tris and EDTA (ethylenediaminetetraacetic acid). EDTA binds divalent cations such as calcium and magnesium. Since these ions help maintain the integrity of the cell membrane, eliminating them with EDTA destabilizes the membrane. Tris is the main buffering component; its chief role is to maintain the pH of the buffer at a stable point, usually 8.0. Additionally, tris likely interacts with the LPS (lipopolysaccharide) in the membrane, serving to destabilize the membrane further.