Organic Phenolchloroform Extraction

Organic extraction involves the serial addition of several chemicals. First sodium dodecylsulfate (SDS) and proteinase K are added to break open the cell walls and to break down the proteins that protect the DNA molecules while they are in chromosomes. Next a phenol/chloroform mixture is added to separate the proteins from the DNA. The DNA is more soluble in the aqueous portion of the organic-aqueous mixture. When centrifuged, the unwanted proteins and cellular debris are separated away from the aqueous phase and double-stranded DNA molecules can be cleanly transferred for analysis. Some protocols involve a Centricon 100 (Millipore, Billerica, MA) dialysis and concentration step in place of the ethanol precipitation to remove heme inhibitors (Comey et al. 1994). While the organic extraction method works well for recovery of high molecular weight DNA, it is time-consuming, involves the use of hazardous chemicals, and requires the sample to be transferred between multiple tubes (a fact that increases the risk of error or contamination).

Stuttering Simple Techniques to Help Control Your Stutter

Stuttering Simple Techniques to Help Control Your Stutter

Discover Simple Techniques to Help Control Your Stutter. Stuttering is annoying and embarrassing. If you or a member of your family stutters, you already know the impact it can have on your everyday life. Stuttering interferes with communication, and can make social situations very difficult. It can even be harmful to your school or business life.

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