(last update : 08-11-1999)

Preparation of gDNA

In eucariotic cells, the DNA is isolated in the nucleus, mitochondria (and chloroplasts). To extract the DNA, it is necessary to remove all the barriers around it. Mostly, proteinase K is used to dissolve the cell membrane and nuclear membrane, and it dissociates the proteins from the DNA. After this step, phenol is added which results in 3 phases in the tube :
  1. The aqueous phase with the DNA, can be precipitated with ethanol.
  2. The interface with denatured proteins.
  3. The phenol phase with the dissolved proteins and fats.
When the DNA is prepared, it can be checked on gel to verify the concentration and quality (sometimes, the DNA is broken down by the enzyme DNAase when the organism isn't preserved correctly for genetic research.)

DNA on gel

Figure 6 : Verification of the prepared DNA on gel

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