DNA extraction is only the first step in exploring the genes that exist in the genome. When we finally have the genomic DNA of an organism, we need to know how much DNA we have and how pure the DNA is. We'll need to evaluate the quality and quantity of our DNA. The quality of our DNA can be examined by using Nanodrop. This enables us to see how purity (A260/280) and concentration of our DNA. This knowledge will influence how DNA we use in subsequent processes like PCR, in-vitro transcription and so on. The ideal purity of DNA is 1.8. Newly extracted DNA is likely to have its A260/280 exceed 1.8, indicating the presence of impurities like RNA. We can visualize our DNA by using gel electrophoresis. We pour agarose gel, containing ethidium bromide, into a rig with a comb. We add specific volumes of our samples and a ladder to the wells formed in the gel by the comb. The ladder is needed as a yardstick against which we can deduce the approximate length of strands. Seeing as DNA is negative, it runs towards the positive end of the gel and add varying speeds depending on the size of a strand. The final gel can be viewed under UV light to visualize the distinct bands.
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