DNA in Strawberries (But no cream!)
Strawberries are the staple food of summer picnics, school fetes and Wimbledon. They are a yummy treat but also can be used for some fun science! Did you know that strawberries have DNA just like we do?
DNA (short for deoxyribonucleic acid) is found in all living things*; animals, plants, fungi and even tiny bacteria. DNA is incredibly thin but also incredibly long. You have millions of miles of DNA in your body, it’s just very well folded up! Try this simple activity to see some real DNA without even using a microsope (adult supervision necessary).
You will need: a strawberry, a couple of beakers or glasses, a small sieve or tea strainer, a ziplock bag, tweezers or cocktail stick, washing up liquid, salt and surgical spirit (available in any chemist). Put the surgical spirit in the freezer at least an hour before you start.
Step one: get rid of any leaves from the strawberry, pop it in the bag and squish it!
Step two: make the extraction mixture. This will break open the strawberry cells so that the DNA can escape. Mix 90ml water with two teaspoons of washing up liquid and a teaspoon of salt.
Step three: add 4 teaspoons of the extraction mixture to your squashed strawberries in the bag and mix GENTLY.
Step four: sieve this mixture to get all the lumps out, we just want the liquid. If you use a small glass (like a shot glass), the DNA will be easier to see.
Step five: finally, pour some cold surgical spirit carefully on top of the strawberry liquid. You should see a cloudy layer forming in the middle. This is the DNA! You can pull it out with tweezers or a cocktail stick and have a look.
*All cellular life on Earth has DNA. Some viruses have another molecule called RNA instead but it’s a bit of tricky question to decide if viruses are actually alive anyway. Of course, we don’t know if any lifeforms that may exist on other planets have DNA or something else entirely.
Emma Ranade spends most of her time exploding things and experimenting at Fab Science birthday parties, holiday clubs, home education groups and school workshops. www.fabscience.co.uk
Dates for summer camps are:
Saffron Walden (RA Butler School): 25th and 26th July
Bishop’s Stortford (Hillmead School): 14th, 15th, 16th August