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Difficulty Beginner
Time Required Very short(< 1 Day)
Prerequisites none
Material Availability Readily available
cost Very low(under $20)
safety No issues

AbstractEdit

All living things have DNA inside their cells. How do scientists extract the DNA from cells in order to study it? In this experiment you can make your own DNA extraction kit from household chemicals and use it to extract DNA from strawberries.

ObjectiveEdit

In this experiment, you will design a DNA Extraction Kit and use it to purify DNA from strawberries.

Materials and EquipmentEdit

  • Measuring cup
  • Measuring spoons
  • 1/2 cup rubbing alcohol
  • 1/2 teaspoon salt
  • 1/3 cup water
  • 1 tablespoon dishwashing detergent (Dawn®)
  • Glass or small bowl
  • Cheesecloth
  • Funnel
  • Tall drinking glass
  • 3 strawberries (green tops removed)
  • Resealable plastic sandwich bags
  • Test tube or small glass jar (e.g., spice jar)
  • Bamboo skewer (find them at the grocery store)

IntroductionEdit

All living things come with a set of instructions stored in their DNA, short for deoxyribonucleic acid. Whether you are a human, rat, tomato, or bacteria, each cell will have DNA inside of it. DNA is the blueprint for everything that happens inside the cell of an organism, and each cell has an entire copy of the same set of instructions. The entire set of instructions is called the genome.

Scientists study DNA for many reasons. They can figure out how the instructions stored in DNA help your body to function properly. They can use DNA to make new medicines. They can genetically modify foods to be resistant to insects. They can figure out the suspect of a crime. They can even use ancient DNA to reconstruct evolutionary histories!

How do scientists get the DNA out of a cell so that they can study it? This is called a DNA extraction, and there are many DNA extraction kits available from biotechnology companies for scientists to use in the lab. During a DNA extraction, a detergent will cause the cell to pop open, or lyse, so that the DNA is released into solution. Then the DNA can be precipitated out of the solution by adding alcohol. In this experiment you will make your own DNA extraction kit from household materials and use it to purify DNA from strawberries.

Strawberries are octoploid, which means they have eight copies of the DNA in their genome in every cell!

Why use strawberries to test your DNA extraction kit? Because strawberry cells each have eight copies of the genome in every cell! When an organism has eight copies, called an octoploid, it has a lot more DNA per cell than an organism that only has one copy. Using DNA from strawberries will help you have a successful DNA preparation so you can purify a lot of DNA.

Terms and ConceptsEdit

To do this type of experiment you should know what the following terms mean. Have an adult help you search the Internet, or take you to your local library to find out more!

  • DNA
  • Genome
  • Extraction
  • Lyse
  • Precipitate
  • Octoploid

Questions

  • How can you extract the DNA out of a strawberry?
  • What does each ingredient do? (detergent, salt, alcohol)
  • Will I be able to see the DNA without using a microscope?

VariationsEdit

  • You can try these steps to purify DNA from lots of other living things. Grab some oatmeal or kiwis from the kitchen and try it again! Which foods give you the most DNA?
  • If you have access to a milligram scale (called a balance), you can measure how much DNA you get (called a yield). Just weigh your bamboo skewer using milligrams before and after the DNA purification. Then subtract the starting weight from the final weight to get your final yield in milligrams (mg).
  • Compare your yield in milligrams (mg) under various experimental conditions:
    • Start with different amounts of strawberries— is more better?
    • Change some of the components of your kit— will other detergents work better?
    • Start with different materials— are there other sources of DNA with higher yields?
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