In this laboratory experiment, students were introduced to DNA electrophoresis. DNA electrophoresis is an instrument that many forensic scientists use to get a DNA fingerprint as an evidence for crimes. Not only can it be used for forensic science, people can use this for paternity test, as well as look for evolutionary relationships among organisms. Agarose is used to make the gel that the DNA fragments are going into. Since DNA particles are negatively charged, the gel is placed in a chamber with positively and negatively charge cords on each side of the chamber in order to separate different DNA fragments. The distance that DNA fragment travels depend on its size and polarity. The farthest that the band of DNA travels to the positive side, the smaller the DNA fragments. DURING THE LAB
For this lab experiment, the mixture of agarose was already pre-made for the students. Students took the warm mixture out of the warm water bath and was instructed to pour the agarose into the gel casting tray that was taped on both side to prevent liquid falling out. After ten to fifteen minutes of waiting for the agarose to solidify, the tapes were removed from both sides and it was placed in the electrophoresis chamber. The students pipetted the dye into the three samples that were given out by the instructor, and loaded each sample into the wells of the gel. After the samples were placed into the gel and closed the lid of the chamber, the power supply was then turned out and make the DNA fragments to travel across the gel. After about thirty minutes of running the gel with the power supply, the casting tray was then taken out and placed into a tray filled with buffer solution. RESULTS
The result of this DNA lab was that there were no result or data collected from running the DNA sample in the DNA electrophoresis. There’s appear to be an experimental error that have caused this outcome. In the lab handout, it said that in the beginning, the students should turn the voltage to 80 and eventually increase it to 120 volts. Due to the time constraint, the instructor made a correction and changed the voltage to about 250-300 volts to decrease the time frame. Instead of letting the electrophoresis run at a low voltage for a longer period of time, we turned up the voltage and shorten the time period. This caused the gel to melt a little because when we took out the casting tray out of the chamber, we can see that the gel was deformed and one end was melted away. The high temperature in the chamber could also cause some damaged DNA fragments and therefore, we could not see any dyed bands in the agarose gel. Although it was a fun experiment, but unfortunately the students were not able to obtain any data from this lab.