Antibiotic Streptomycin Lab Report

Introduction:

This experiment includes the use of a genome editing system in order to make E.coli cells resistant to the antibiotic streptomycin. The system uses a protein called Cas9. Guide RNA is used to guide the Cas9 to the targeted sequence of DNA. The Cas9 finds the match to the gRNA in the cell’s DNA and cuts it out. As the cell tries to repair the DNA, it uses the template DNA that was inserted into the cell, and results in the modified DNA. In the case of this experiment, the goal is to create streptomycin resistant E.coli. Streptomycin works by binding a ribosome to prevent it from making proteins, so the cell cannot replicate. The CRISPR-Cas9 system will work to change a single base from A to C which will code for a protein that prevents the streptomycin from binding to the ribosome. The expectation for the experiment is that the control bacteria will not survive

The p-value from the experiment was 0.0754, which shows that there were other factors affecting the experiment, since a p-value of less than 0.05 is required for an experiment to not be random chance. Also, 3 colonies in the first group, 5 colonies in the second group, and 34 colonies in the third group grew on the LB/Strep plate even though the bacterial cells were not genetically edited. This displays that other factors could have caused the bacteria to grow on the antibiotic infused plates, and that editing the DNA was not the only reason the bacteria grew on the LB/Strep plates. The experiment might not have worked due to possible pipetting error when transferring multiple aspects in the CRISPR-Cas9 system. Also, the antibiotic could have been defective, due to the fact that the unedited bacteria grew on the antibiotic. In addition, there could have been cross-contamination which would cause other bacterial colonies to grow that were resistant to the antibiotic in the first place. For all of the reasons stated, the experiment was