Question: how do you make a DNA sample using liquid?

Ruth Elderfield answered on 19 Jun 2015:

It depends what the liquid is. If it is blood or saliva they will have cells floating in them, these cells will have DNA inside, we can pull out the DNA using a detergent (like washing up liquid) mixed with salt which breaks down the cells protective layers (membranes) and releases the DNA in the liquid. Then you can use a concentrated alcohol to make the DNA float to the surface so you can pick it out.
This is a link to the method of how to get DNA out of strawberries written by Carolyn Jones:
https://www.murdoch.edu.au/Biotech-out-of-the-box/_document/Kit-Handout-Sheets/DNA-extraction-from-strawberries.pdf