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LadderDNA ladders have fragments of specific length and can be used to estimate the molecular size or fragment length. The bands in the ladder are usually 2-3 times more intense then the other bands for easy identification (Thermo Fisher, 2016). DNA ladders contain a set of known DNA fragments composed of multiple sizes and are separated as DNA bands on a gel. It is called a ladder because when the bands appear on the gel it looks like a ladder. DNA ladders are used in gel electrophoresis so the size of base pairs in each fragment can be determined.
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Loading DyeA loading dye contains two different dyes, the first one being bromophenol blue and the second is xylene cyanol FF. The bromophenol blue is what stains the DNA and then xylene cyanol FF is the tracking dye, which has a negative charge and travels the same way as DNA. The EDTA in the solution binds divalent metal ions to stop metal dependant nucleases (Thermofisher, 2016). There are 2 main purposes of a loading dye, first off there is lots of glycerol present which makes the solution denser than water, and will therefore sink to the bottom of the well instead of just staying in the buffer (Addgene). The second purpose is that the dye is coloured, and therefore, allows you to visualize where the gel is as it is being run (Addgene).
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