Written by: Aminah Rangwala
Transformation of bacteria can date earliest back to the 1900s and has evolved ever since, where scientists have been making discoveries about our genetic material, DNA, that they didn’t know existed. Bacteria is essential for the growth of the human growth cycle and can be classified into the branch of Prokaryotic. They are needed for the decomposition of organic matter and have later been seen to transform.
Bacterial transformation can be classified as the process of transferring a foreign genetic material into a cell. Bacteria contain their DNA as plasmids or small circular disks that carry a gene of interest. Therefore, one of the main purposes for bacterial transformation is to introduce a plasmid into a bacteria and replicate the plasmid in the cell to see further results that you are testing for. Another use of bacterial transformation includes duplicating DNA, called DNA cloning. In other words, a gene of interest is derived from a testing source and inserted into a plasmid. This new plasmid is referred to as a recombinant plasmid or recombinant DNA. To see if a transformation is successful, the DNA will be incorporated into one of the cell’s chromosomes.
In the midst of bacterial transformation, there is also a process called gel electrophoresis. Gel electrophoresis is a process that is used for separating nucleic acids or other macromolecules based on their size, shape or physical properties. Bacteria can be closer analyzed with this method and this technology allows us to study the sequence, expression, and function of a gene.
As shown in the picture to the right, samples of DNA such as ones from bacterial transformation are placed into wells or indentations in the gel on one side. Each well can be labeled based on the bacteria and each side of the gel is either positive or negative. The smaller bands of DNA move quicker whereas the larger bands of DNA move slower. This is identified as the different sized molecules form bands in the gel. Because DNA is negatively charged, gravitationally, the DNA will attract to the positive side of the gel.
As I was once an AP Biology student, my fellow science group conducted a lab based on the many processes of bacterial transformation and gel electrophoresis. This lab is very common but my team and I were very interested to see what results we had discovered from it. The purpose of the lab was to determine the bacterial transformation pGLO has on E. coli. To define terms in this experiment, we used E. Coli as bacteria and pGLO, a plasmid that contains GFP, green fluorescent protein, beta lactamase and also the araC regulator protein. The GFP contains the gene in the plasmid coded for producing a glow which was originally derived from a jellyfish. Beta lactamase is an enzyme that contains the ampicillin resistance and araC, arabinose, which contains the expression of the GFP gene.
By using four different test petri dishes, with different factors applied to them, we added the plasmid DNA to only two of the petri dishes and saw what each plate looked like after the growth and incubation periods. The LB stands for the broth that was placed at the bottom of each plate. The results were fascinating and we found that the plate with the LB/amp with the pGLO, showed growth only to cells that contained the pGLO plasmid. The second plate with pGLO, LB/amp/ara showed major growth of bacteria and could even glow under a UV light due to the GFP that was expressed in the plasmid. The two other plates without the pGLO plasmid showed either the bacteria spread across the plate or there was no growth at all. To add, other factors that may have altered the growth of the bacteria could have been the incubation periods, heat shock and recovery time.
To conclude, this experiment as well as the discoveries based on gel electrophoresis and bacterial transformation are eye opening and truly show us how cells and bacteria react to genes of interest. In the real world, bacterial transformation and gel electrophoresis can be applied to forensics. In forensics, suspects or crimes of people can be eliminated if the DNA pattern of the suspect does not match those of what was tested based on gel electrophoresis. Pretty cool! Not only does this show the conditions of bacteria and their stages, but can overlook what other findings that can be made in the future!
Works Cited:
Image Credit:
Helyx Graphic Designers