Science Fair Salvation: How to make a double-helix DNA Model

Tomorrow is National DNA Day. Who knew! I can’t think of a better time to share this tutorial to make a DNA model. If you have a child in school, grandchildren, a young neighbor, or maybe you’re friends with a few teachers, pin this DIY DNA tutorial. The next time you hear about a last-minute science fair project, designer Kathleen George has you covered! I’m also sharing the results of my dog’s official DNA test.

Pin this for later! How to make a double-helix DNA Model for a school project or science fair.

First, a little DNA humor:

Q. What did one DNA say to the other?

A. Stop copying me!

And now, here’s how to make your own double-helix DNA model.

To make a DNA Model, you will need:

  • STYROFOAM™ Brand Foam: 46, 1” balls; scrap piece
  • Wooden skewers, eight
  • Acrylic craft paint: yellow, white, orange, pink, bright green and dark green (or six different colors of your choice)
  • String
  • Chopsticks or ¼” wood dowel
  • Thick, white craft glue
  • Tools needed: Scissors; toothpicks; stiff bristle paintbrush; knippers

Finished size: The DNA Model is approximately 17” long, including the hangers.

Pin this for science class projects and science fairs. Step-by-step tutorial to DIY a double-helix DNA Model.

DNA Model by Kathleen George.

To make a DNA Model:

1. Insert a wood skewer through the center of each 1” foam ball. Rotate the skewer to smooth out the inside and the edges around each hole. This will make it easier to string the balls.

2. Insert a toothpick into each ball, which you’ll use as a handle when you paint the balls.

3. Paint the balls:

  • Paint 16 balls yellow. These will represent sugar.
  • Paint 14 balls white. These will represent phosphate.
  • Make four groups of four balls each for the nitrogenous bases.  Paint each group of four a different color (Kathleen used bright green, dark green, pink and orange paint). Four balls will represent cytosine; four will be guanine; four will be thymine; and the last four are adenine.
  • Once the balls are painted, insert the toothpicks into a scrap of STYROFOAM Brand Foam to hold the balls upright while the paint dries.
  • Let the paint dry thoroughly.

4. Cut two, 28” lengths of string. Spread white glue to cover 2-1/2” on one end of each string. Roll the ends between your fingertips to work the glue into the string. Hang the strings over the edge of your work surface to dry. When dry, the stiffened ends will make it easier to thread on the balls.

5. Prepare the pairs of nitrogenous bases. Using knippers, cut the wood skewers into eight, 3” lengths. Thread two balls onto the center of each skewer:

  • Make four pairs of one cytosine with one guanine
  • Make four pairs of one thymine and one adenine.
Super helpful tutorial to construct a DNA model.

Follow this diagram as you build your DNA model.

6. Thread eight yellow sugar balls and seven white phosphate balls onto a string, starting and ending with a yellow sugar ball and alternating the colors as you go. Tie a large knot 3” from the end, and glue the knot in the hole at the bottom of the ball at the end of the string. Don’t cut off the excess string. Squeeze a drop of glue at the top of each hole to secure the balls. Repeat, creating a second string with the balls in matching order.

7. Add the pairs of nitrogenous bases, inserting the skewers into the yellow sugar balls. Be sure to insert the skewers firmly into the balls; add a drop of glue if needed to help hold it in place.

Detail of a DIY DNA Model. Great for science class! Pin and save this one.

insert the skewers into the yellow sugar balls.

8. Cut a chopstick or ¼” wood dowel into two, 8” lengths to create the hangers. Tie the strings onto hangers and add a dab of glue to hold the strings in place. Trim off the extra string. To create the look of the double helix, twist the double strands in a counterclockwise direction.

How to test your dog's DNA.

JoJo is an all-American mutt.

I shared the story about our pup’s DNA test a few years ago, but I imagine most of you didn’t see it. My daughter fell head-over-heels when she saw JoJo at the shelter, and he’s been our best buddy ever since. When my daughter studied DNA in science class, we decided to officially test JoJo’s DNA. It’s an easy process – we swabbed his cheek and sent the swab to the lab. The results confirmed that JoJo is an all-American mutt with traces of Chihuahua and Maltese. Most of JoJo’s DNA is so mixed up that it’s too hard to identify.

And that’s o.k. with us. I’ve always had mutts and they’re my favorite kind of dog. How about you – is there a breed that holds a soft spot in your heart? Or are your furry friends mutts, too?

Happy crafting.




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8 Responses to Science Fair Salvation: How to make a double-helix DNA Model

  1. cathy says:

    how do you get the double helix to stand upright?

    • Sharon says:

      You will need to construct a stand to hold the model upright. Perhaps you could fashion a stand from an old hanger, and form a hook in one end to hang the model, and then insert the hanger into a block of STYROFOAM Brand Foam. You could then attach the bottom end of the DNA model into the foam block, too. Does that make sense? Let me know, please, if you have any other questions. Good luck! Sharon

  2. CraftyB says:

    Love the DNA humor and what a great educational craft!!

  3. This is really cool! I wish I had seen it yesterday because my grandsons were here for the day. Maybe next vacation we can make this!
    We have always had mutts up until the last few years when we got a black lab, then a border collie and another black lab. The labs are such a gentle breed but I would really love to get a pit bull mix. They make such wonderful pets and are so devoted!

    • Sharon says:

      Hi Barb, whether it’s mutt or purebred pup, they’re our best buddies! I had a lab mix once and she was very sweet — and a little crazy! Did you do any crafting with your grandsons? Sharon

  4. Angie F says:

    Where did you send your pup’s DNA sample to test it? Our doggy [also a JoJo :)] is supposed to be a Pitt bull boxer mix. It would be neat to see what a test would say.

    • Sharon says:

      Hi Angie, We used Canine Heritage, but I believe they’re now called Wisdom Panel. I found another outfit online, too, called DNA My Dog and they seem to provide more levels of information. It’s fun, with sometimes surprising results. If you have your dog tested, let me know how it turns out. Sharon

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