Restriction Fragment Analysis
This technique enables researchers to compare the DNA
of different individuals. This technique makes use of Gel
Electrophoresis, except that it hybridise the separated DNA
fragments with a radioactive probe.
The two or more
samples of DNA to be compared are separated by electrophoresis, on
the same piece of gel. Each of them will form a characteristic
pattern of bands.
A sheet of nitrocellulose paper
is pressed onto the gel. Capillary action will pull the separated
fragments onto the paper, in such a way that they are positioned
in bands exactly as on the gel.
The paper blot is
exposed to a solution that contains radioactive labeled probe. The
probe is single stranded DNA complementary to the DNA sequence of
interest, and it will pair complementarily with the separated
A sheet of
photographic film is laid on the paper. The radioactive probe will
cause images to show up at places where there are DNA fragments.
These images can be compared to tell the difference between the
samples of DNA being analysed.
- Gel Electrophoresis