extracting dna

• Extracting DNA from Fruit


  1. Gently mix together 50ml cold water, half a teaspoon of salt and 10ml washing up liquid

  2. Gently heat this mixture at 50C for 5-10 minutes

  3. Peel the skins of a kiwi (or strawberry) and chop into small pieces

  4. Pulverise the kiwis

  5. Add the solution from Step 1 to the kiwi

  6. Filter the solution using a few sheets of kitchen paper and a sieve

  7. Pour the filtrate into a test tube

  8. Add 10ml of pineapple juice to the filtrate and allow to rest for a few minutes

  9. Add 2 teaspoons of cold ethanol to the solution and wait 10 minutes
• What should we see?


  • A white mass should precipitate at the top of the tube after 10 minutes; this is the DNA from the kiwi
• Why do we add pineapple juice?

  Pineapple juice contains an enzyme called bromelain which breaks down proteins attached to the DNA. This helps us see the DNA more clearly.
• Why do we add ethanol?

  Ethanol causes the DNA to precipitate out of the solution - making it visible at the top of the container.