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Genomic DNA Isolation (Lab 4H)

Our Genomic DNA Isolation kits is supplied with dried E.coli and all the ncessary prealiquoted components to isolate bacterial genomic DNA from the bacteria and use G-Biosicences Nucleic Acid Assay to determine the amount of DNA extracted. In addition, a class demonstration is include to demonstrate that the supplied dried bacteria are viable.

The following laboratory activity is adapted from “Laboratory 4h: DNA Extraction from Bacteria” from Biotechnology: Laboratory Manual by Ellyn Daugherty. For more information about the program, please visit This kit is produced under license from Paradigm Publishing, Inc., a division of New Mountain Learning.

Negatively charged DNA molecules are hydrophilic and dissolve well in watery solutions. On the other hand, charged DNA molecules are repelled by nonpolar solutions such as alcohol. Scientists exploit this characteristic, and use alcohol to isolate DNA by precipitating (separating) it out of solution. This kit uses alcohol precipitation and centrifugation to isolate DNA strands from other molecules found in cells.

Maybe you have experienced spooling DNA strands from prepared solutions. Alcohol precipitation and DNA spooling can be used to pull long strands of DNA out of a solution and wrap them around a glass rod. The tighter the strands are spooled around the rod, the more water is pushed out of the solution and the DNA around the rod goes from looking like goopy mucous to white strands. Pure, dry crystalline DNA is white.

In research labs, DNA spooling is not done. Instead, DNA isolation is done in micro test tubes using centrifugation and alcohol precipitation. In this activity, bacteria cells are broken open using a buffer containing a detergent and then a protease treatment. When the bacteria cells burst, they release DNA, and the detergent and protease initiate the breakdown of contaminant proteins. Heat and high salt washes denature more protein contaminants. Using a centrifuge, cellular waste is pelleted and discarded. The genomic DNA, floats in the supernatant above the waste and is pipetted off and precipitated into a clean pellet using alcohol and high-speed centrifugation. The pelleted DNA is dissolved in TE Buffer and stored at -20°C for later use. Samples of the purified genomic DNA may be studied using indicators or gel electrophoresis.


  • Demonstrate viable bacteria
  • Isolate genomic DNA from bacteria
  • Use an assay to determine the amount of DNA
Material Safety Data Sheet
Technical Literature
Life Science Educational Program  A guide to the educational training products offered by G-Biosciences

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