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Witton Middle School



Having investigated inherited and environmental variation within humans, we are now going to find out more about how some of those characteristics are inherited.


DNA was discovered in 1869 by a scientist called Friedrich Miescher who isolated it from pus on used bandages (yuk!). But he didn't know how its atoms were arranged or even what its function was. It wasn't until the 1920s that scientists realised that DNA had some role in carrying genetic information. The next challenge was to work out its structure to unlock the secrets of how it did this extraordinary job.



We are going to follow the same clues to see if we can discover the structure for ourselves. Get some scrap paper and try to draw what you think the molecule might look like after each clue. 


The double helix structure is very famous. Can you make your own model? You might like to try origami or using sweets. I used magnetic building blocks. Send me a photo to add to the gallery!


To think about:

  • What are the limitations of your model?
  • What are the strengths of your model?
  • How could you improve your model?


You need to be able to describe the part played by James Watson, Francis Crick, Maurice Wilkins and Rosalind Franklin the development of the DNA model. Create a fact file on each one. Categories could include:

  • Born:
  • Died:
  • Education:
  • Scientific work:


Possible websites:



If you happen to have these things at home and have a grown-up with time to help, you may like to try this experiment to extract DNA from strawberries. An adult will need to put a bottle of isopropyl alcohol (or surgical spirit) in the freezer beforehand. Remember, though, that not all experiments work!