A recent DNA gel electrophoresis experiment was conducted in attempt to include or exclude a suspect regarding his positive genetic relationship to a child. Of interest was the concern of whether or not the suspect could be the child's father. In pursuit of the answer, three sets of DNA were collected: that of the mother's, the child's, and the suspect's. Each individual had a control set of DNA as well as another set cut with the Hind III enzyme, therefore a total of six DNA samples were micropipetted into six wells set in an agarose gel. Unfortunately, the Hind III enzyme was defective and therefore uncut and cut sets of DNA on the resulting picture were identical, thereby rendering the experiment unable to include or exclude suspect from inquiry. Such unexpected findings concluded further testing must be performed, preferably via PCR, to determine whether the suspect in question is genetically related to the child or not.
[...] The more allele's two DNA samples have in common, the more genetic material the two individuals have in common, thereby rendering them “related.” To perform DNA gel electrophoresis, DNA samples are collected and cut by restriction enzymes, enzymes that locate their respective recognition sequences on a DNA strand and make a cut between two designated nitrogenous bases, to make fragments of DNA. These fragments are then separated by size via electrophoresis, a process more clearly defined in the below paragraph, and like fragments with the same number of repeated sequences between working genes congregate at on the electrophoresis gel plate. [...]
[...] Here, it was important to remember which side was which DNA sample so that when the photographs of the DNA bands were made, it would be possible to compare one sample to another. New tips were used each time so that a total of six tips were used. The tip was lowered just above the bottom of the well and slowly pressed to first stop and then pressed down to second stop. Second stop was not released until the pipette tip was pulled out of the gel to prevent liquid from coming back up the tip. [...]
[...] There was the question of whether the enzyme was overwhelmed by the DNA samples or not, along with the idea that perhaps the enzyme had not been treated correctly (not kept in cold temperature and therefore allowed to denature) and micropipetted in correct distributions to the DNA samples. Or perhaps a partial digestion occurred in which the enzyme did not fully cut the DNA. However, because mass data—other groups performed identical experiments—was inaccurate, as others experienced the same error of having uncut and cut samples appearing identical, it was concluded that the enzyme Hind III itself was faulty. [...]
[...] This may be due to embryonic mutations, during which the child's alleles from the mother changed and therefore were no longer identical to their predecessors. In the experiment, all the uncut DNA of each individual was designated to be the control, so that the resulting cut DNA after electrophoresis could be compared with the status quo. However, due to obvious errors, both the cut and uncut DNA of each individual were the same. This was a critical error because as a result, no conclusions could be made other except to suggest retesting. [...]
[...] Both a MiniVisionary imaging system and Transilluminator made the stained and staggered DNA fragments visible. The imaging device was toggled to focus and show enough contrast so that the DNA bands could be visible on the photograph. The photograph was then printed and given to respective group members. The photographs were immediately labeled with M0, B0, S0, and based on the corner that was taken out, which showed the order in which the different DNA samples were placed. The lab area was then cleaned and the equipment used was disposed of properly. [...]
Online readingwith our online reader
Content validatedby our reading committee