Practical - DNA Extraction (OCR Gateway GCSE Biology: Combined Science)

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Extraction of DNA from Fruit

Observing DNA in the Lab

  • This is not a core practical but still a worthwhile experiment
  • The molecular appearance of DNA is very familiar, but can we actually extract this important molecule from cells and look at it?
  • DNA can actually be extracted from fruit using some basic classroom equipment
  • Fruits that have relatively large amounts of DNA in their cells
    • Strawberries, bananas and kiwis can be used


  • Mash the fruit and mix this into a beaker containing a solution of detergent (e.g. washing up liquid) and salt
    • The detergent breaks down the cell membranes (and the nuclear membranes), causing the fruit cells to release their DNA
    • The salt causes the DNA to stick together

  • Filter the mixture into a test tube
    • This removes any debris (big, insoluble bits of cell) from the mixture

  • Gently add some ice-cold ethanol to the filtrate (the filtered mixture) by pouring the ethanol slowly down the side of the test tube
    • This causes the DNA to precipitate (i.e. to come out of solution) as DNA is not soluble in cold alcohol

  • The DNA will appear as a stringy white precipitate (a solid)
  • If needed, this precipitate can be carefully extracted using a glass rod

Extracting DNA from fruit, downloadable IGCSE & GCSE Biology revision notes

A simple method for extracting DNA from fruit

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Author: Phil

Phil has a BSc in Biochemistry from the University of Birmingham, followed by an MBA from Manchester Business School. He has 15 years of teaching and tutoring experience, teaching Biology in schools before becoming director of a growing tuition agency. He has also examined Biology for one of the leading UK exam boards. Phil has a particular passion for empowering students to overcome their fear of numbers in a scientific context.