| MadSci Network: Biochemistry |
Hi Denise,
When you say, washing up liquid, I assume that you mean liquid soap. In general, liquid soaps contain the detergent sodium laurel sulfate. In DNA extraction protocols, this detergent is used to disrupt the cell membrane, permitting DNA to be released into solution. The science behind this DNA extraction protocol is explained here. More information about DNA extraction protocols can be found in the MadSci Archives.
You also asked, "What is the protease used for in order to isolate DNA from a plant tissue?" in a second question. I'm going to just answer that here as well, because it is related.
Any number of proteases can be used to assist in digesting the enzymes that are associated with DNA in the cell, as well as those that might serve to digest the DNA that we are trying to extract. Meat tenderizer is used In this DNA extraction protocol, and many meat tenderizers contain the protease papain. When I do a DNA extraction, I usually use the enzyme Proteinase K.
Keep asking those questions!
Try the links in the MadSci Library for more information on Biochemistry.