In this activity, students crush strawberries and use detergent and salt to break the cell wall so that DNA will be released into the solution. When alcohol is poured slowly over the top of the solution, DNA will rise to the surface. Students can spool the DNA with a stirring rod or toothpick. Because strawberries have multiple copies of DNA (octoploid), the extraction is simple and works every time! Even very young students can do this! You can even do this in your kitchen with some supervision.
Equipment for the experiment is easy to acquire. If you don’t have beakers, plastic cups will work! Use plastic sandwich bags to crush strawberries with a solution of salt and detergent. (Instructions are included in the handout.)Then filter the crushed strawberries using a funnel and coffee filters.
You can download the worksheet with instructions, or even project them and walk students through the steps. Students can even take their DNA samples with them in small microcentrifuge tubes.
For advanced classes, you can have students compare different samples. Kiwis, saliva, and fresh peas are great for DNA extraction!
Grade Level: 5-12 | Time Required: 30 min
HS-LS3-1 Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring