DNA fingerprinting can be utilized as a means of
identifying people. I actually work as a DNA
analyst for a crime laboratory and we utilize
a type of DNA fingerprinting technique for
catching criminals. We look at short tandem
repeats (STRs), which are areas in the DNA that
have three to four base pair repeats (e.g.
AGATAGATAGATAGATAGAT). We are able to amplify or
copy several different regions (called
loci) of DNA that are known to have these
repeat sequences. A region or loci with more
repeats will be longer (because there are more
base pairs). As such, we are able to determine the
number of repeats in a particular locus by how
long these regions are. For example, TPOX is a STR
we use. You might have 8 repeats in TPOX region.
Since you get one copy of your DNA from mom and
the other from dad, some regions will have two
different repeat numbers. For example, you might
be an 8 and 9 repeat for TPOX. We look at many
different regions of your DNA, which allow us to
put together a genetic profile that can be used to
identify you (your genetic fingerprint).
When we get evidence in, we look biological
material that may be there (like blood) and then
isolate the DNA. We then quantify the DNA and
amplify it using special chemicals that allow us
to figure out the genetic profile of the person
that left the biological material on the evidence.
This is then compared to the known profile of any
suspects or other people that may have had contact
with the evidence.