Kitchen becomes laboratory: How to extract DNA from a strawberry
Sometimes it's difficult to get kids interested in science. In school the concepts are often too abstract and technical for them to really get a grasp on how it applies to the real world. But the following experiment makes science, well at least biology, exciting, and it involves extracting DNA (deoxyribonucleic acid), a hot topic for anyone who's into police and crime shows. It's an easy experiment and you probably already have everything you need for it right it in your kitchen.
- a strawberry
- a sealable freezer bag
- a strainer
- a funnel
- a cup
- a pipette
- 4 fl oz cold rubbing alcohol
For the extraction solution:
- 2.5 fl oz warm water
- 1/2 tsp salt
- 1 tbsp dishwashing detergent or liquid laundry detergent
First make the extraction solution by mixing the water, salt, and detergent in a bowl. Put the strawberry in the freezer bag and add 1 to 3 tbsp of extraction solution.
Squeeze the air out of the bag and seal it.
Softly squash the strawberry in the bag.
Place a coffee filter or some cheesecloth over the funnel and pour the contents of the freezer bag into the cup. The leftover pulp should not go in the cup. Instead, wring it out as much as possible and then dispose of it.
You can also use a sieve for this part of the process.
Now add the cold rubbing alcohol to the fluid you emptied from the freezer bag. You'll soon notice small threads forming — these are strands of DNA. You can extract these from the liquid using the pipette.
There's not much you can do with strawberry DNA, but that's not really the point of the experiment. The idea is to observe the little lump of slime that is actually the building block of life. It's fascinating to think that all living organisms are based on this seemingly simple little blob of information.
To get a closer look at this incredible substance, you can put it on a plate and observe it through a magnifying glass. Even better is a microscope if you have one.
You can watch the whole experiment being performed in this video...
You can try this experiment using any kind of soft fruit or vegetable; bananas also work really well, for example. It's a great way to experience the science all around us!