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DNA Extraction protocol by FIg19vk

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									                                                                              BIOL 1111L
                                                                            DNA Extraction

                                       Lab Topic 8
                                      DNA Extraction
Written by Samantha Fowler, Clayton State University, Morrow, GA.

Objectives
Upon completion of this exercise, you will be able to
   understand that DNA can be readily extracted from cells.
   understand the purpose and applications of doing a DNA extraction.
   describe the major steps to extracting DNA.


Introduction
Because it is the blueprint for life, deoxyribonucleic acid (DNA) is found in all living
organisms. There are many practical applications for the analysis and manipulation of
DNA. The field of forensics uses it to eliminate suspects from a crime. Courts use it to
establish paternity. Ecologists use it to determine the genetic variation and overall
health of a population. Evolutionary biologists compare DNA sequences between
individuals to establish evolutionary relationships. Geneticists use it to detect heritable
disorders. Biotechnology uses it to genetically engineer organisms for medical
purposes, such as the production of insulin, or to create heartier agricultural plants. The
more biologists learn about DNA, the more endless the possibilities of what can be
done. However, before DNA can be studied, it must first be extracted from the cells of
an organism in a process called DNA extraction.

There are three basic steps to extracting DNA from cells. First, the cells must be lysed
(broken open) so that the DNA can be exposed. This is done by agitating the cells in a
blender or grinding them. Second, the DNA is separated from the other parts of the cell
in a buffer solution. The two main parts to the solution are: 1. a surfactant or detergent
that disrupts the lipids in the cell membrane, and 2. salt, which helps remove proteins
from the DNA and keeps them from precipitating with the DNA. Third, the DNA needs to
be removed from the rest of the cell. This is done with alcohol. The DNA is insoluble in
the alcohol causing it to form into a clump, leaving the salty buffer solution and
remaining parts of the cell parts behind.




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                                                                              BIOL 1111L
                                                                            DNA Extraction

                               Exercise 8.1
                       DNA extraction from a banana
Materials
   0.9% sodium chloride solution.
   Dawn Dishwashing soap.
   95% Ethanol
   Mortar and pestle
   Test tube and test tube rack
   Scissors
   Cheese Cloth
   Glass Stirring Rod
   Banana
   25 ml Graduated Cylinder

Procedure
   1. Place half a banana into a mortar.

   2. Add 10 ml of 0.9% sodium chloride solution and grind the material with the
   pestle for 2-5 minutes. The more mashed up the better.

   3. Strain the solution through 3 or 4 layers of cheese cloth or filter paper into
   a test tube.

   4. To the suspension add 1.5ml of Dawn detergent (4 drops).

   5. Measure the total sample volume; then measure out 2 times that amount
   of 95% ice cold ethanol.

   6. Gently add the ethanol to your cell suspension.

   7. Use the glass stirring rod to gently stir the mixture until the DNA begins to
   appear at the interface of the ethanol and suspension.

   8. Twist the glass rod to spool the DNA sample on to the rod. Twist the rod
   clockwise for best results.




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