We transformed E coli cells with a plasmid modified to contain a ‘virulence factor’ which would allow growth on media containing the antibiotic kanamycin (Kan). The plasmid confers constitutive resistance to ampicillin (Amp). The bacterial experiment is
Bacterial Genomics
The study of the morphological, physiological, and evolutionary aspects of the bacterial genome is referred to as bacterial genomics. This subdisciplinary field aids in understanding how genes are assembled into genomes. Further, bacterial or microbial genomics has helped researchers in understanding the pathogenicity of bacteria and other microbes.
Transformation Experiment in Bacteria
In the discovery of genetic material, the experiment conducted by Frederick Griffith on Streptococcus pneumonia proved to be a stepping stone.
Plasmids and Vectors
The DNA molecule that exists in a circular shape and is smaller in size which is capable of its replication is called Plasmids. In other words, it is called extra-chromosomal plasmid DNA. Vectors are the molecule which is capable of carrying genetic material which can be transferred into another cell and further carry out replication and expression. Plasmids can act as vectors.
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We transformed E coli cells with a plasmid modified to contain a ‘virulence factor’ which would allow growth on media containing the antibiotic kanamycin (Kan). The plasmid confers constitutive resistance to ampicillin (Amp). The bacterial experiment is about understanding whether such a ‘virulence factor’ confers physiological adaptation to Kan or whether the development of resistance can be explained by random mutations.
For each independent transformation we re-suspended the cells from three colonies in Luria broth. For each suspension of cells we plated 100 microliters on a Kan plate. To estimate the number of cells seeded on each Kan plate we made four serial dilutions that were plated on Amp plates (1 – 4) and we counted the number of cells growing on them. From this we extrapolated how many cells had been seeded on the Kan plate. Then we normalised the Kan results for all the plates, assuming that every plate had been seeded with 10[5] cells.
Consider two Kan plates, each with 4 colonies. The Amp dilutions plates they are associated with are Amp(4) [meaning the fourth dilution] with 20 colonies and Amp(3) with 200 colonies, respectively. What are the expected number of colonies on the two Kan plates once they are normalised to 10[5] seeding cells. Select only one answer.
1. 4 and 4
2. 200 and 20
3. 200,000 and 200,000
4. 200 and 200
5. 20 and 20
6. 2 and 2
7. 2 and 4
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