EtBr absorbs light in the ultraviolet UV range and emits orange light. Gels are viewed with special transilluminators containing UV lights. EtBr is a light-sensitive compound, so stocks are stored in the dark.
The 1 kb ladder shown in this student gel is a proprietary mixture of linear DNA fragments ranging in size from 0. The staining intensity of bands on agarose gels reflects the quantity of DNA in the band, because EtBr intercalates fairly evenly along the length of linear DNA molecules. The greater intensity of the 3 kb fragment serves as a useful orientation marker in situations where smaller fragments might have run off the end of the gel or when some markers are not well resolved from one another.
These are common occurrences! Note that the shortest molecules on the gel are more well separated from one another than the longer molecules. The PCR products that you will be analyzing in this lab are mostly in the bp range.
To increase the resolution of these molecules, we will use 1. This will reduce the resolution of larger DNA molecules. Note also that smaller bands appear fuzzier on the stained gel, because they have been more affected by random diffusion as they have migrated through the network of agarose polymers.
Agarose gels are porous matrices Several factors affect the migration of DNA through agarose gels Fluorescent intercalating agents are used to visualize DNA molecules in gels Standards are used to estimate the sizes of DNA molecules Agarose gels are porous matrices Agarose is a polysaccharide purified from red algae, or seaweed.
Several factors affect the migration of DNA through agarose gels Because of the negative charge of the phosphate residues in the DNA backbone, DNA molecules move toward the positive pole anode of the electrophoresis apparatus. Download preview PDF. Skip to main content. This service is more advanced with JavaScript available. Advertisement Hide. Authors Authors and affiliations B. Guo M. Prinz M. Conference paper. This process is experimental and the keywords may be updated as the learning algorithm improves.
This is a preview of subscription content, log in to check access. These results indicated that the electrophoretic traps were more heterogeneous in the lower concentration gels. FIGE experiments, in which the forward pulse times were varied, were done to determine an average distance that a circle traveled before trapping occurred.
Pub Type. Bioscience , DNA and biological evidence and Health. Cole, K. Created January 1, , Updated February 19,
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