DNA Extraction Lab
Name_______________________________________
I can:
 Conduct an experiment safely to extract DNA, following directions and using tools properly.
 Describe the process of DNA replication including where it happens in the cell, why it is necessary
in a cell, and the enzymes used during the process.
DNA Extraction Background Information:
There are three basic steps in DNA extraction. The cell must be lysed (broken open) to release the nucleus
(nucleus must also be opened to release the DNA). Then the DNA must be protected from enzymes that will break
it down, causing shearing. Finally once the DNA is released, it must then be precipitated (separated from solution)
in alcohol.
In order for the cell to be lysed, the lipid cell membrane walls must be broken down. The detergent and salt
solutions accomplish this. Cell walls, cell membranes, and nuclear membranes are also broken down by the action
of gently rocking and stirring the solution. Finally, the Alcohol is used to precipitate the DNA. In water, DNA is
soluble. When it is in alcohol, it uncoils and precipitates leaving behind the other cell components that are not
soluble in alcohol.
Materials Needed:
Sodium chloride solution
Liquid soap solution
Paper Cup
Bottled or Distilled water
Test Tube and Stopper
Isopropyl Alcohol
Procedure:
1. Gather together sodium chloride solution, liquid soap, bottled or distilled water, test tube
and stopper, glass rod, a plastic cup and isopropyl alcohol.
2. Previously, 8 grams of sodium chloride has been dissolved with 92 milliliters of distilled
water. Pour 1 milliliter of this sodium chloride solution into a large test tube.
3. Previously, 25 milliliters of liquid soap has been combined with 75 milliliters of distilled
water. Add 1 milliliter of liquid soap to the test tube.
4. Pour 10 milliliters of the bottled water into a plastic cup and swish vigorously in your
mouth for 30 seconds.
5. Spit the water back into the cup and pour the contents into the test tube containing the
sodium chloride solution.
6. Cover the top of the test tube with a stopper and gently mix the contents by turning the
test tube upside down and right side up.
7. Add 5 milliliters of the rubbing alcohol to the test tube making sure to pour it at an angle
down the side of the test tube.
8. Wait for about 5 minutes and watch as the DNA floats to the surface.
Questions: Make sure to explain your answers.
1. What are the three main steps to DNA extraction?
2. What was the function of the detergent?
3. What did your DNA look like?
4. A DNA molecule is made of what three parts?
5. Identify the 2 purines and the 2 pyrimidines.
6. Explain Chargaff’s rule.
7. Where in the cell does DNA replication occur?
8. What is the end result of DNA replication?
9. Why is DNA replication necessary?
10. What is the function of DNA polymerase?
11. What is the complimentary DNA strand to: CTAGGTACT?
12. Briefly describe and draw the process of DNA replication using the following terms: helicase, double helix,
DNA polymerase, and DNA ligase. (Challenge yourself and use Okazaki fragments, leading strand, and
lagging strand).