Electrophoresis

For whatever purpose or whatever information is being sought out, every DNA test involves electrophoresis. This individual process allows the parts of a DNA molecule to be separated in gel or through a synthetic capillary, using an electrical current. Once the DNA sections have been separated and marked during electrophoresis, they can be identified in a lab.

After a DNA sample has been amplified using a process known as PCR, it can then be separated by electrophoresis. This process essentially uses an electrical current to separate DNA molecules, yet this also needs to be done in a certain environment. There are two environments used in contemporary DNA tests; gel and capillaries filled with a different gel. Gel electrophoresis was an invaluable discovery made in the 1970s, which allowed laboratory scientists to abandon the meticulous and time consuming process of separating DNA by gravity and do it quickly instead.  

In gel electrophoresis the amplified DNA sample is placed into a gel matrix which is sponge-like in its composition. Each section of the DNA is then pulled in two ways by the negative electrical current on one end and the positive electrical current on the opposite. When charged, the DNA moves smoothly through the gel’s spongy substance at different rates, so at one end the larger parts will remain and the smaller ones will move towards the other. The DNA is then dyed with ethidium bromide so that it can be ‘read’ or analyzed by a laboratory professional.   Capillary electrophoresis is similar to its gel counterpart in that it takes place in gel and the parts are dyed for analysis afterwards. While the gel is a little different the capillaries essentially act as a guideline for the separated DNA sample to travel through, when the gel and sample are charged with electricity from the two opposing electrodes. How fast a DNA segment travels through the capillary is shown by its length once died and the longer ones denote smaller segments which travel through the gel quickly.  

Electrophoresis is the final intricate and physical process to be used in DNA profiling before a sample is analyzed, but it’s also completely indispensable. Without electrophoresis a DNA sample remains essentially ‘locked’ within its own shape and cannot be analyzed by human nor machine.