Brooke Tucker
Mr. Newman
Forensics
11 December 2014
DNA Fingerprinting
DNA fingerprinting is a test used to identify and determine the genetic makeup or DNA
in a person’s cells. For example, DNA fingerprints can be used for determining a biological
mother or father to identifying a suspect of a crime. DNA fingerprints aren’t actually
fingerprints. In fact, DNA fingerprints have nothing to do with fingerprinting. DNA
fingerprinting got its name because it is very unique like fingerprints. Also because like
fingerprints it’s very unlikely that two people have the same DNA information.
The process used to create a DNA fingerprint is called gel electrophoresis. Gel
electrophoresis is a process that uses electricity to sort DNA strands into their different lengths.
The first step to take before creating your DNA fingerprint is to make a Jell-O like gel that you
will load the DNA sample into. The gel is made out of agarose, a dried powder like gelatin.
Then, pour restriction enzymes into the DNA. The restriction enzymes will cut the long DNA
fragments at different locations. The lengths of the fragments will vary from person to person
because the code of each person’s DNA is different. Now, pour the agarose gel into a tray. The
gel will act as a strainer for the DNA molecules. It will allow the smaller DNA to move more
easily. Pour your DNA into the tray and turn the electrophoresis box on to begin electrophoresis.
At the end of the process the fragments will be distributed in the gel according to length. Next,
place a nylon membrane on top of the gel to act as an absorbent. Add probes and then place an
X-ray film on top of the nylon membrane, so pieces of the corresponding areas are exposed. The
last step is to develop the film in the developer.
When my class completed this lab we did it a little different from the experts but still got
the same result. Our first step was preparing the gel bed by placing rubber dams on each end of
the bed and then placing a template (comb) in the first set of notches at the end of the bed. The
second step was to cast the agarose gel. We used a 125 mL flask to prepare the gel solution.
First, we heated the mixture of 0.25g of agarose powder and 30.0 mL of buffer to dissolve the
powder on a hot plate. We covered the flask with foil and then turned the hot plate on high. The
mixture was heated until boiling and all the agarose was dissolved; we then let the beaker sit and
cool until the agarose solution was 60 degrees Celsius. The solution was then poured into the bed
and allowed to completely solidify; it was placed in a container and stored in a refrigerator. The
third step was to load the samples. We placed the gel bed on a flat surface and then loaded the
DNA samples in tubes A-F into the wells. The fourth step was running the gel. After loading the
DNA samples we placed them into the apparatus with the wells facing the negative side. We then
poured the buffer into the apparatus until the gel beds were completely submerged. Next, connect
the apparatus to the power source and set to low voltage; check that the current is flowing
properly by looking for bubbles. The last step is to turn the power source off after the designated
time and look at the gels to see how far the DNA traveled.
There are many advantages in using DNA fingerprinting; however there are also many
disadvantages in using it. One advantage is that it can be used to help determine a biological
relationship, such as who a child's father is, or can be used to prove beyond a reasonable doubt,
that a person was present during a criminal activity. DNA fingerprinting can also be used to
identify dead bodies that can't be recognized in other ways, so it’s fairly conclusive. A
disadvantage of DNA fingerprinting is that it better at proving family relationships rather than
specific ones. It would require a whole lot more work to accurately prove a specific relationship
like if two brothers were being accused of fathering the same child. Another disadvantage is that
DNA fingerprinting is expensive and takes a lot of time. Therefore, it is not very useful for
everyday identification purposes. Fingerprints are much better and easier to process/store. In
short, it's expensive and time consuming, but fairly accurate under the right conditions.
A new DNA technology may improve the treatment of an aggressive childhood cancer,
known as Neuroblastoma. Neuroblastoma is a form of cancer, that is the most common
childhood tumor outside of the brain, and the one that has been the most difficult to treat.
Researchers are using high-resolution DNA technology, to develop a new way to analyze the
genes that causes relapses into this disease. Neuroblastoma starts in the nervous system of
infants. The treatment is modified to the genetics of the cancer cells and when relapses occur it
usually signifies a bad prognosis. Prior research has shown that a change in the ALK gene, which
controls the division rate of cancer cells, affects the risk of both occurrence and reoccurrence of
neuroblastomas. However, a newly improved method which is based on a sensitive DNA
sequencing technology, has allowed researchers to succeed in identifying a number of specific
genetic changes that influence the risk of reoccurrence. Researchers hope this leads to new
treatments for children suffering from this disease. One of which pharmaceutical companies have
recently developed with drugs that target the mutated ALK gene. These treatments are big steps
for patients who suffer from Neuroblastoma caused by mutations in the ALK gene. A professor
at Karolinska Instituted and pediatric oncologist at the Karolinska University Hospital Astrid
Lindgren Children's Hospital hopes to start new treatments over in Sweden as soon as possible.
He plans to take samples of the tumor which will be taken to check for possible ALK mutations
both when the patient is first diagnosed and at any later relapses. The samples will also be
analyzed using high-resolution DNA sequencing technology. He’s quite hopeful the initial
results will be promising.
In conclusion, DNA fingerprinting is a method used to determine the DNA in a person’s
cells. The process used to create a DNA fingerprint is gel electrophoresis, which sorts DNA
strands according to length through electricity. There are also advantages and disadvantages in
using DNA fingerprinting. Nevertheless, the use of DNA in modern society is just getting
started. DNA is being used in many different ways and has become a great advance in many
breakthroughs in the science and medical field.