Here we show how to extract DNA from a banana using household items and easy-to-find reagents.

*PROTOCOL*
You can download a 1-page protocol from [ Ссылка ]

*USING MORE REAGENTS*
We deliberately use the minimum possible number of reagents, but you can add a few more for further accuracy. For example, you could add a pinch of salt right before adding the ethanol in step 7, to aid the precipitation of DNA (but as you can see here, it precipitates fine without). Similarly, you can add a few drops of pineapple juice to the filtered liquid or to the lysis solution, to eliminate some proteins. This is because pineapple has bromelain, an enzyme that breaks up proteins, so this would give us purer DNA. However, it would not look very different, so we decided to leave it out in this case in order to have a simpler protocol, and just mention that the DNA is not pure. Also, it would have the obvious problem of having a second fruit into the mix, with its own DNA. Alternatively, you could use contact-lens washing liquid, which also has proteases, but this introduces a black-box reagent that we would rather avoid.

*DNA FROM OTHER FRUITS*
You can also follow this protocol to extract DNA from tomatoes and strawberries. The problem with tomatoes is that they have a lot of pigments (chiefly lycopene) that often stain the DNA, which should be colourless. Try with your local fruit and tell us in the comments how it went!

*YOUR OWN DNA FROM SALIVA!*
Extracting your own DNA from saliva is surprisingly easy:
1. Wash your mouth well using only water.
2. Gently rub the inside of your cheeks and lips against your gums, teeth and palate, to dislodge some cells (saliva itself has no DNA).
3. Spit some saliva directly into a test tube or vial (about 1 or 2 cm or 1/2 inch in height will do).
4. Add a couple of drops of washing up liquid.
5. Mix very well.
6. Add the alcohol just as we did in step 7.

*REFERENCES*
[ Ссылка ] | [ Ссылка ]

*RESEARCH*
Victor Sojo & Aishwaria Lohi.

*VIDEO*
Victor Sojo & Janina Roemer.
Developed at Aavishkaar: Centre for Excellence in Maths and Science (aavishkaar-palampur.org), in collaboration with Science Corps (science-corps.org) and Eduversum (eduversum.org)

*SUBTITLE TRANSLATIONS*
Hindi: Apoorwa.
Castillian (Spanish): Victor Sojo.
German: Janina Roemer.

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