Sodium dodecyl sulphate (SDS) is a detergent that is commonly used in the process of DNA extraction. Its primary function is to lyse the cell membrane and nuclear envelope, allowing the release of cellular components, including DNA. SDS achieves this by disrupting the lipid bilayer structure of the cell membrane and dissolving the hydrophobic proteins associated with it. This leads to the breakdown of the cell's physical barriers and the release of the cell's contents.

In the context of DNA extraction, SDS plays a crucial role in freeing the DNA from within the cell and making it accessible for further processing. By breaking down the cell membrane and nuclear envelope, SDS facilitates the release of DNA into the extraction buffer, where it can be subsequently purified and analyzed.

SDS is typically used in combination with other reagents such as proteinase K or RNase to ensure the complete lysis of cells and the removal of cellular debris. The use of SDS in DNA extraction is a fundamental step in various molecular biology techniques and is essential for obtaining high-quality DNA for downstream applications such as PCR, DNA sequencing, and genetic analysis.