If you use grocery store fruit this lab yields a great deal of DNA. I have used this for quite a few years and obtain great results every year.

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Background

The native wild or wood strawberry, Fragaria vesca, has only two sets of chromosomes (diploid), but the grocery store strawberry, Fragaria ananassa,  has eight sets of chromosomes (octoploidy) and will supply an abundance of DNA.  So, commercial strawberries make an excellent subject for collecting DNA.  

Another reason strawberries work so well is that they are soft and easy to smash.  Also, ripe strawberries produce enzymes (pectinases and cellulases) which help in breaking down the cell walls making it easier to extract the DNA.

 After completing this lab, you will have a sample of pure strawberry DNA and you will never again look at a strawberry in the same way.

Materials

• Zip seal plastic bag
• 1 strawberry
• 10 ml lysis buffer
• cheesecloth
• small plastic cup
• 95% ethanol (ever clear)
• ice water bath
• test tube
• Plastic stir stick
• Safety goggles

Safety Precautions

• Most of the chemicals are fairly mild but treat all chemicals with respect.
• Wear safety goggles. 
• Make sure you wash your hands after the lab.

Lysis Buffer Recipe

Mix 100 ml of dishwashing liquid, 15 grams of salt and then add water to make 1 liter.  Stir but do not shake.  You do not want a lot of bubbles.  For the best results mix the lysis buffer a couple of days before you need it.  The mixture has a great shelf life if you keep it in a clean, covered container.

Notes

Remember that DNA is polar and will dissolve in water.  So, it is the ethanol that causes the DNA to precipate.  Keep the ethanol ice cold and you will get better results.

Click here for the pdf