This blog post was inspired by the people who searched variations of ‘cool science projects to do at home’ and ended up looking at my blog! Since there is clearly a demand I thought I would share an experiment I did with my goddaughter – it shouldn’t be too problematic and it’s really fun for a whole range of ages, although younger children will need supervision.
Extracting kiwi fruit DNA
Kiwi fruit DNA is exactly the same as your DNA, which contains all the genes that were necessary to make you and for you to continue to live; for you to grow and your body to be maintained.
You do need a few things you may not have immediately to hand so you’ll need to plan ahead a little bit. As with any scientific protocol you should read through the whole thing before you start!
You will need:
- 1 Kiwi fruit
- Surgical spirit – keep away from small children and whatever you do, do not drink it. (I’ve found boots own brand to work well, it states ethanol and methanol rather than Industrial methylated spirit which is what most supermarkets sell)
- Economy washing up liquid
- Salt – ordinary running table salt, the cheaper the better, you want fine salt not large sea salt crystals
- 2 glasses
- Ice cubes – at least 15
- Paper coffee filter
Put the surigcal spirit in the freezer a couple of hours before you want to use it. Make sure the lid is firmly closed. The colder it is the better and it won’t freeze so you don’t need to worry about the bottle breaking.
Make DNA extraction solution: Add 10mls (2 teaspoons) of salt into 90 mls of water stir to dissolve the salt and add 10mls (2 teaspoons) of washing up liquid. Stir gently, try not to make bubbles! If you have a measuring jug with 100ml mark on it, add the salt and some water, then the detergent and then top up gently until you reach the 100ml mark.
Peel the kiwi fruit and weigh 30g – if your scales just have 25g marks weigh enough kiwi to be just over the first mark. This will be approximately half a kiwi fruit.
Mash the kiwi with a fork – or you can use a hand blender to make the job quicker if you have one. Put the mashed up kiwi into a glass.
Pour the DNA extraction solution over the fruit until you have about double the volume of fruit alone, this will roughly be half the DNA extracting solution you made up but if you pour in too much don’t worry.
Prepare some hot water in a saucepan or bowl, the water should be 50 – 60 degrees C if you have a thermometer, if you don’t the water should feel hot but should not be hot enough to burn you. Do not use boiling water.
Stand the glass in the hot water for 20 mins stirring gently every 5 mins. If the water starts to feel a bit cool you can add more hot water or heat it in a saucepan briefly half way through. Do not boil the water or the kiwi mixture.
Take the ice cubes and wrap them up in a plastic bag or sandwich bag, wrap them in a tea towel and break them up with a rolling pin or something similar. The ice cubes don’t need to be in very small pieces but if you break them up they will work better. Put the ice in a dish or bowl large enough to put the glass in.
After the kiwi mixture has been in the hot water for 20 mins take the glass out and place it in the bowl of ice and put the whole bowl in the fridge for 15 mins, stir every 5 mins. You can just put the glass on ice and not worry about putting it in the fridge if you make sure it’s completely surrounded by the ice.
After the kiwi mixture has been in the fridge for 15 mins pour the mixture into the coffee filter. Put the coffee filter into the funnel – if it doesn’t all fit or if you don’t have a funnel you can rest the coffee filter in a sieve or something similar and pour in a small amount of the mixture at a time, be careful not to let it pour out of one side, it needs to be filtered before you use it for the next stage. Be patient and don’t try to force it through the filter.
Once at least two table spoons have filtered through into a new glass you can stop. This will take around 10 mins. The more you filter the more DNA you will get.
Take the surgical spirit out of the freezer (or off the ice) tip the glass a little and pour about 1 table spoon gently down the side of the glass. Do not stir. If you have a bit more than two table spoons of kiwi mixture use a bit more.
You should see a green kiwi layer on the bottom and a clear layer of surgical spirit on top. Between the two, above the kiwi layer a white precipitate will form this is the DNA. It will be mucus like, try pulling it out of the glass with a fork but be gentle and don’t mix the layers or you’ll loose it again.
That’s actual DNA you’re now playing with, it’s exactly the same as your DNA would look and feel!
I’m sorry about the lack of photos and movies, I’ll update this and add some when I get a chance. I thought I would go ahead and post it whilst I had some time on my hands and there were some bank holidays someone might be looking to brighten up with some cool science!
If you try this I’d love to hear about how it went and if anything is unclear or you have any problems with it let me know so that I can make it clearer or add extra advice.