You don’t need a lab or fancy equipment to find DNA—the genetic instructions for all living things. Learn how to extract DNA from strawberries in your own kitchen!
As with all science experiments, safety is extremely important. We recommend wearing safety goggles for this experiment. Parent supervision is required.
But first, what is DNA?
Supplies You’ll Need:
- Isopropyl Alcohol
- Liquid Dish Soap
- Zip Lock Bag
- Small Glass Cup
- Large Glass Cup
- Measuring Cups
- Two Spoons
- Safety Goggles
- Put the bottle of the Isopropyl Alcohol in the freezer – about fifteen minutes before starting the experiment! You want the alcohol cold but not frozen.
- Pour 90 ml (or 18 tsp) of water into a cup.
- Then add 10 ml (or 2 tsp) of liquid dish soap to the water.
- Next add 1/4 tsp of salt to the water and soap mixture. Stir the salt until it dissolves. Once it dissolves your extraction solution has been completed.
- Pour the extraction solution into the zip-lock baggie.
- Place one strawberry in the baggie with the solution and push out as much air from the bag as possible. Then seal the bag.
- Now is the fun part! Use your hands to mash the strawberry up inside the bag. Make sure there are no large chunks of strawberry left. You want it really mushy!
- Next take the contents inside the plastic baggie and pour it through the strainer into the large glass cup. You can mash down on the mixture with a spoon to get as much liquid pushed through as possible.
- Once you have as much of the strawberry/extraction mixture in the large cup, pour the contents into the small glass cup.
- Remove the isopropyl alcohol from the freezer. Measure out 5 ml of the alcohol and pour it slowly into the strawberry/extraction mixture.
- Hold the small glass cup up to your eye. You will notice that there is a separation in the two liquids with a white layer at the very top.
- Take a tweezer and run it through the white layer. You will find that there are solid parts in the layer. This is the strawberry’s DNA. You can gently use the tweezers to pull the DNA from the glass cup.
What is happening?
As you learned in the steps above, the long stringy white pieces that you pulled out of the glass cup with your tweezers are actual strands of strawberry DNA. Strawberries have a lot of DNA when compared to other fruits. This makes the strawberry DNA not only easy to extract but also visible to see.T he extraction mixture played a crucial role in the extraction process. Strawberries are made up of cells that have an outer layer called membranes. The liquid dish soap in the extraction solution helps to dissolve those cell membranes. Inside those cells are also protein chains that hold nucleic acids. The salt in the extraction solution will break up the protein chains and release the strawberry’s DNA. You added isopropyl alcohol to keep the DNA from being dissolved in the extraction solution.
- DNA- (n.) is the building blocks of any organism. It acts a guidebook to instruct the body on how to develop and function.
- Cell Membrane – (n.) the outside layer or wall of a cell.
- Protein Chains- (n.) large chains of amino acids.
- Amino Acids – (n.) the necessary parts of every cell in your body that produce proteins in order for you to survive.
- Nucleic Acids – (n.) the building blocks of any organism – DNA is just one type of nucleic acid.
- Dissolve – (v.) the act of something breaking up and disappearing into something else.