The way the fingerprint is done is that first a
sample of DNA from a person is found. That sample
is usually from human cells, blood, saliva or hair
(with the root attached). The DNA is then cut up
using molecules that cut DNA in a certain way.
Then "probes" are added which light up when they
bind a particular piece of DNA. In the case of DNA
fingerprinting, these particular pieces of DNA are
certain sequences that repeat over and over again,
but the number of times they repeat is different
in different people. This generates an image that
looks like a bunch of bars, kind of like a
barcode. In a real sense, the DNA fingerprint
achieved is a barcode for a person in that it
uniquely identifies people.
There are other ways to get a DNA fingerprint,
but they all rely on looking at certain places in
the genome that we expect to be different and
comparing how these places look in different
people. So the classic case is if a criminal
leaves behind blood, they can do a DNA fingerprint
on the blood of the criminal and the crime scene
blood and see if the "bars" on the fingerprint are
in the same places.
Click Here to return to the search form.