Today we quantified DNA that was extracted in an earlier lab session. A single sample of DNA was split into two, one being treated with RNase while the other was not. Each was measured using a spetrophotometer, which tests the absorbance of just one microliter of the sample, just enough to form a drop. The greater the absorbance, the more DNA in the sample. The sample treated with RNase is expected to have a lower absorbance because the RNA is degraded. It turns out that a lot of the "stuff" extracted was also RNA along with the DNA. Our absorbance for the RNase-treated sample was a bit lower than expected, meaning our DNA sample was not very pure. We then did gel electrophoresis with our samples. With each sample, both the RNase-treated and non-RNase-treated samples, we diluted some to 50%, which resulted in a total of four samples. Each of these four samples were treated with loading dye to allow it to sink when loaded into the gel and indicate the migration of the samples across the gel. We poured the gel with a dye added to it that will allow the samples to be visible under blue light. After the gel had solidified, we loaded a standardized DNA ladder into the first two wells. We then loaded five microliters of each sample into the next four wells. We ran the gel at 100 volts for 30 minutes, and we viewed the gel under blue light to illuminate the migrated samples. As expected, the samples treated with RNase only had one stripe, which the samples that weren't treated with RNase had two, one that represented the DNA and one that represented the RNA. The DNA was longer in length, so it did not migrate as far as the RNA, which formed a stripe much farther down the gel. Also as expected, the diluted samples had fainter stripes, showing that there was less DNA and RNA contained.
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