Science Models
Science Fair Projects

Strawberry DNA Extraction

Published on May 15, 2017


In this experiment I am trying to find out if the temperature of Ethanol effects the amount of DNA extracted from Strawberries. I got this experiment idea when I went on a tour at the BC Cancer Agency. There, they told us what they did, and how they read and stored DNA.They also explained where they stored the information from DNA. We also got to extract DNA from a strawberry. Now thats where my first thought came from!


What is DNA?

DNA is short for deoxyribonucleic acid.

Although DNA looks like very thin long strings under a microscope, it turns out that DNA has a specific shape. This shape is called a double helix. On the outside of the double helix is the backbone which holds the DNA together.

There are two sets of backbones that twist together. Between the backbones are the nucleotides represented by the letters A, T, C, and G. A different nucleotide connects to each backbone and then connects to another nucleotide in the center.

There are four different types of nucleotides: adenine, thymine, cytosine,and guanine. They are usually represented by their first letter:

A= Adeninr

T= Thymine

G= Guanine


A always goes with T and G always goes with C.

DNA or RNA? Even though DNA and RNA both contain genitic informatin, they have a difference.

But before I answer that question, What is RNA?

RNA stands for Ribonucleic Acid. A Nucleic Acid is in every living thing. Its role is to act as the messenger and carry instructions from DNA for controlling the synthesis of the proteins. But in some viruses, RNA gives the instructions and DNA carryes them.Now that I explained what RNA is, lets go back to the real question, DNA or RNA?

Here are some differences between DNA and RNA: 1. DNA has 2 strands and RNA only has one. 2. Thymine is replased with Uracil in RNA. 3. DNA can be replicated, but RNA is synthesized from DNA.=


The hypothesis is that the temperature of the Ethanol affects the amount of DNA extracted from a Strawberry. My hypothesis is that the hot ethanol at temperature 62 C might not work because the ethanol might evaporate, then there won't be enough Ethanol to break the cell wall. If the Ethanol is cold, and the strawberry is also cold ( at temerature 1C ), it might not work. But if the Ethanol is room temperature( 14 C) it might break the cell wall.


• 3 Ethanol bottles – 40 ml ethanol in each

• 12 Strawberries – all same size and weight

• Weighing scale to measure the weight of strawberries

• Buffer (mix about 30 ml of dish detergent and 7.5 ml salt into 500 ml of water)

• 12 cheese cloths

• 12 Ziploc bags

• 12 Test Tubes and caps - medium size

• Paper Towels

• 1 tube rack

• Gloves

• 100 ml measuring Erlenmeyer flask

• 3 Funnels

• Labels for test tubes

• 3 Droppers

• 12 mini test tubes

• 1 ruler

• Thermometer


Before Experiment:

1. Keep all the test tubes in the tube rack.

2. Before you start the experiment, take 9 strawberries and put one in each Ziploc bag. Then freeze them for 1-2 days in the freezer. Make sure you don’t have any air in the bag before you freeze the strawberries.

3. Put one ethanol bottle (40 ml) in the refrigerator so that it is cool and take it when you are at the part of the experiment where you need to add ethanol. Put the other 2 ethanol (40 ml each) bottles with the rest of the materials.

4. For the experiment you will need a buffer (mix dish detergent and salt into water) If you have any left-over you can poor it down the sink or use it again to do this experiment again. Keep this mixture in 100 ml measuring flask

5. Take 3 test tubes and label them, “Hot”, “Cold”, “Room” to indicate the temperature of ethanol used for the experiment. Hot – 60 degrees Celsius, Cold – 5 degrees Celsius (approximately)

6. Take 3 mini test tubes and label them, “Hot”, “Cold”, “Room”

The Experiment:

1. Mash the strawberry through the Ziploc bag in your hand. Be gentle and easy not to break the bag or hit against the experiment materials.

2. Add 1 tablespoon of Buffer solution and continue mixing and mashing the strawberry till it becomes a homogenous mixture.

3. Place the cheesecloth in the opening of the funnel and keep the funnel in the test tube that is marked “Room”. We will be using the other two test tubes when we use ethanol at Hot and Cold temperatures.

4. Carefully pour the strawberry mixture into the test tube making sure to catch the solids with the gauze. Take extra precaution not to let any solids go into the test tube by holding the cheese cloth with a finger.

5. Hold the cheese cloth ends with one hand while squeezing the contents with your fingers to extract more juice.

6. Slowly add the ethanol at room temperature to the test tube. Take care not to tilt or tip the test tube; do not mix the two liquids.

7. Close the test tube with the cap and gently tilt the test tube up and down for 5 times.

8. Observe the line between the strawberry mixture and the ethanol. You will notice a white thread-like cloud appearing at this line. This is strawberry DNA. The DNA will clump together and float to the top of the alcohol layer

9. Take the dropper and lift the clump together into a mini test tube marked as “Room”

10. Measure the amount of DNA collected by marking the measurement with a sharpie.

11. Now repeat the entire experiment from step 1 till 10 using Cold (5 degrees Celsius) and Hot (60 degrees Celsius) Ethanol (. Also ensure to use test tubes and mini test tubes marked as Hot and Col respectively.

12. After completing the experiment with three types of Ethanol and getting the
measurements, compare the amount of DNA collected with three different temperatures of ethanol and record the findings.


Here are the results of the experiment:

Strawberry DNA


Based on the above results, the amount of DNA extracted is highest when the Ethanol temperature is higher than the others.



DNA by Natalie Hyde

Genes & DNA by Richard Walker