DNA Extraction: Strawberry
Problem or Purpose
The purpose of this lab is to find the DNA of a strawberry in order to see what DNA
If the lab is successful, then the DNA will be extracted from the cells and will be more
DNA is located in every cell; it can be extracted easily using everyday materials. We will
use a salt based extraction buffer to dislocate protein chains that bind around the
nucleic acids. We will also use dish soap to dissolve the fatty part of the cell wall and
nuclear membrane. By completing these steps, we will be granted access to the cells
? Ziploc bag
? 1 of the provided living sources (strawberry)
? 10 mL DNA extraction buffer (soapy, salty water)
? Coffee filter
? Test tube
? Inoculating loop
? 10 mL isopropyl alcohol
1. Place one strawberry in a ziploc bag.
2. Crush the strawberry using your hands for 120 seconds. ?Be mindful to not bust
3. Pour the 10 mL of extraction buffer (soap and salt solution) to the bag.
4. Knead/smash the strawberry in the bag once more for 60 seconds.
5. Put together your filtration contraption as shown above with the coffee filter in the
6. Pour the strawberry slurry into the filtration contraption and allow it to filter
straight into the into your test tube.
7. Remove filtration contraption then gently pour cold isopropyl alcohol into the
8. Immerse the inoculating loop into the test tube where the strawberry extract and
alcohol layers meet. OBSERVE.
Before extraction The strawberry appears to be squashed, squishy, pulpy, and red.
During extraction The strawberry has started to separate and become lumpy.
After extraction Strands start to form, appears to be a bit transparent, and sticks
Results and conclusion
1. The purpose of filtering the strawberry slurry through the coffee filter was to
separate components of the cell.
2. The purpose of mushing the strawberry with salty/soapy solution was to break up
proteins and dissolve cell membranes.
3. The initial smashing and grinding of the strawberry was to break open the cells.
4. The addition of isopropyl alcohol to filtered extract was to precipitate DNA from
5. What biomolecule is DNA?
DNA is made up of the biomolecule nucleic acid.
6. What is the monomer of DNA?
The monomers of DNA are nucleotides.
7. What is the monomer made out of?
Nucleotides are made of a nitrogenous base, phosphate molecule, and a
5 carbon sugar.
8. What are the nitrogenous bases of DNA and how do they pair up?
The nitrogenous bases are adenine, thymine, cytosine, and guanine.
Adenine is always paired with thymine, and cytosine is always paired with
9. How does DNA differ from RNA?
RNA has a ribose sugar instead of a deoxyribose sugar like DNA.
10. What did the DNA look like? Relate what you know about the structure of DNA to
what you observed today in the lab.
The DNA looked like white, thin fibers clumped together. The structure of
DNA is in strands, so the strands were clumped together and formed what i saw
in the lab.
11. Explain what happened in the final step when you added isopropyl alcohol to
your strawberry slurry in the test tube.
The DNA was brought out of the solution
12. A person cannot see a single cotton thread 100 feet away, but if you wound
thousands of threads into a rope, it would be visible much further away. Is this
statement similar to our dna extraction? Explain.
You can't see a single strand of DNA with the naked eye, but when there
are thousands of threads of DNA, you will be able to see the large groups of
threads of DNA.
13. Why is it important for scientists to be able to remove DNA from an organism?
List two reasons and explain.
Being able to remove DNA helps scientists study the genetic causes of
diseases by giving them DNA to observe and compare. It also is important in
determining paternity because they can compare both the DNA of the child and
the adult being tested.
14. Is there DNA in your food? How do you know?
Yes, everything we eat comes from other organisms that contain DNA, so
that means we also consume DNA.