The 'Southern blot' technique
It is a method to detect DNA sequences in given DNA sample.
1. DNA strands are cut into smaller pieces using enzymes (proteins that initiate activity)
2. These DNA pieces, called fragments, are run through a gel that seperates them based on size
3. The DNA is denatured, i.e., it loses its function and activity
4. A nylon sheet (membrane) is placed on top of the gel and pressure is applied to make sure the impression of the gel is compied onto the sheet. The gel and the sheet bind because the gel is negatively charged and the sheet is positively charged. Opposite charges attract.
5. The membrane is exposed to a probe- a single pice of DNA whose sequence's presence is to be determined in the target DNA
And that's the technique in a nutshell! Some other techniques include: 1) Northern blot 2) Western blot