DNA Extraction

Scientists isolate DNA for a variety of reasons, some of which include:

• genetic testing

• body identification

• analysis of forensic evidence

Steps

1. collection (e.g., mouth)

2. burst cells open to releases DNA

   • lysis solution

     • detergent - disrupts cell membrane and nuclear envelope, causing the cells to burst open and release their DNA

     • proteinase K - cuts histones (where DNA is tightly wrapped around) to free DNA

   • place the tube in warm water bath

   • concentrated salt solution

     • salts causes proteins and other cellular debris to clump together

3. Separate DNA from proteins and debris

   • place in the centrifuge

     • supernatant - DNA

     • pellet - proteins and debris

4. isolate concentrated DNA

   • isopropyl alcohol

     • precipitation (DNA is not soluble in isopropyl alcohol)

   • centrifuge

     • supernatant

     • pellet - DNA