Electrophoresis is a process used by scientists to help understand what fragments of DNA they are examining. This can help in identifying different DNA for criminal cases, in diagnostic medicine and, in some cases, this can be used as a reliable paternity test. Electrophoresis results in each individual’s unique DNA “fingerprint.”
The process of electrophoresis separates each of the DNA strands by size. This helps scientists to better understand what DNA they are viewing. When they separate the DNA molecules by size, this is what creates the DNA “fingerprint.”
A gel is used in this process to hold the DNA. The gel is made up of a substance called agarose. The gel is made with small pits in the top of the gel structure. These pits will hold the DNA segments.
DNA and Phosphate
The backbone of the DNA is made up of a sugar-phosphate pattern. This pattern runs through the entire length of the DNA. Due to the fact the phosphate compound is negatively charged and it runs throughout the entire length of the DNA, the DNA is negatively charged.
Electrical current is placed at one end of the gel, with positive electrodes at the top of the gel -- closest to the pits with the DNA inside -- and negative electrodes at the bottom. Due to the fact DNA is negatively charged, it will move through the gel toward the bottom and the positive electrodes. The gel will offer resistance for the DNA, so it will take larger strands a longer time to pass through the gel than shorter strands. The process is stopped at a predetermined time, and wherever the DNA is in the gel, that will give an indication of how large each of the strands were. This final image, after the electrophoresis, is the DNA “fingerprint.”