Extract Strawberry DNA

Overview

Students will explore genetics and cells by extracting the DNA from a strawberry! 

DNA

Experiment Length

30 min

day 6

Key Vocabulary
  • DNA (deoxyribonucleic acid): contains the genetic code for everything in our bodies, from what we look like to how our bodies work! Located in the nucleus of all of our cells and made up of nitrogenous bases.

  • Nucleus: the control center of the cell that contains 23 pairs of DNA chromosomes and is bound by a double membrane.

  • Chromosomes: made up of DNA strands wound around proteins that hold the DNA in an x-like shape. We have 23 pairs of these chromosomes in each of our cells! In one pair, one chromosome comes from your mom and the other from your dad.

  • Double helix: describes the ladder-like backbone of DNA molecules which consist of two DNA strands wound tightly around each other

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click the worksheet above to print!

materials
  • Dish soap

  • Plastic cup

  • Strainer

  • Tweezers

  • Strawberries (works best with strawberries, but other fruits can be used!)

  • Measuring cup

  • Measuring spoons

  • Salt

  • Isopropyl Alcohol (hand sanitizer works, too!)

  • Water

  • Ziploc bag

steps
  1. Place the isopropyl alcohol in a freezer

  2. Measure 90mL (a little over 3 fl oz) of water into a small glass or container

  3. Add two teaspoons (10 mL) of dish soap to the water 

  4. Add ¼ teaspoon of salt into the mixture and stir until the salt dissolves

​You have finished your extraction mixture!

  1. Place one strawberry in a ziploc bag

  2. Place the extraction mixture into the ziploc bag containing the strawberry

  3. Remove as much air as possible from the bag before sealing it tightly 

  4. Use your fingers to smash and mush the strawberry in the bag so that no big pieces remain

  5. Pour the strawberry mixture through a strainer into a glass container and use the measuring spoons to mush the strawberries so any excess juice is squeezed out

  6. Transfer the strawberry mixture to a small container that holds around ¼-½ cups of liquid 

  7. Add 1 teaspoon (5mL) of the chilled isopropyl alcohol to the mixture

  8. You should see a separation of liquids in the container with a white layer on top of the liquid. This is the strawberry’s DNA! Use tweezers to pick it up and observe it.

the science

Wow! The extracted DNA you see is present in all living organisms, plant or animal. It’s even inside us! The reason we use strawberries for this experiment is because they contain eight copies of each type of DNA chromosome while humans only contain two sets of chromosomes, and they have way more DNA than other fruits. Each part of the extraction mixture played a big part in the experiment. The soap dissolved the cell membranes where the strawberry’s DNA is held while the salt released the DNA strands from the protein chains holding them together. The isopropyl alcohol caused the DNA to precipitate, or turn into a solid, because DNA doesn’t dissolve in alcohol, especially when it’s freezing cold. 

Taking it further

Try using other fruits in the experiment, like bananas or kiwis! Which fruits work the best? Why do you think that is?

 

Try extracting DNA from your own cells! Take a Q-tip and swab the inside of your cheek to capture some cheek cells and place them in the ziploc bag instead of the strawberry. Does a similar result occur?

 

Learn more about what makes up DNA!

Inspired by Steven Spangler Science

Special thanks to Honor Pimentel for the Spanish translation

daily challenge

Post your photos and video on social media with #curieusinquarantine or send them to us at curieusinquarantine@curieus.org for an entry into our raffle!

We will select one lucky kid tomorrow to win a free Curieus swag bag with a Curieus shirt, stickers, and candy. Submit your entry to curieusinquarantine@curieus.org by 8 pm this Saturday (May 23rd)!

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