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Home / Science projects / Build a DNA Model
  • Build a DNA Model

    Build a DNA Model

    To help further understand how DNA is structured, build a model of it. This is a simplified model of DNA, but it will still give you the general idea of how the sugars, phosphate groups, and bases all connect together to make the famous double helix shape of DNA. You can make a model out of a variety of materials. Here's how you can do it with candy.

    What You Need:

    • Red and black hollow licorice sticks
    • Gummy bears
    • String
    • Toothpicks
    • Small white marshmallows

    What You Do:

    1. Cut the red and black licorice sticks into one inch strips.
    2. Make two equal lengths of licorice strands by threading the pieces of licorice onto the string, alternating the red and black pieces.
    3. Gather together four different colors of gummy bears, the marshmallows, and the toothpicks.
    4. Pair two colors of the gummy bears together and then pair two other colors together. For example, red and orange gummy pairs could be paired together, and green and yellow ones be paired together.
    5. Take a gummy bear and thread it onto the toothpick. Thread the marshmallow onto the toothpick so that it is in the center of the toothpick and next to the gummy bear. Thread the complementary gummy bear onto the toothpick so that it is next to the marshmallow. You should now have a toothpick with a gummy bear-marshmallow-gummy bear centered on it.
    6. Repeat step five to make more gummy bear-marshmallow toothpicks, making sure the gummy bears are matched with their complementary colors. Make as many of these toothpicks as you have red pieces on one of your licorice strands.
    7. Take one strand of licorice and start attaching the gummy bear-marshmallow toothpicks to it, connecting one of these toothpicks at each of the red pieces on the strand. Then, take the second licorice strand and connect it to the other side of the toothpicks. Again, connect the toothpicks to the red pieces of licorice. You should end up with a 'ladder' with the red and black licorice stands making the sides of the ladder and the gummy bear-marshmallow toothpicks making the rungs of the ladder.
    8. Hold your candy ladder up and turn the top counterclockwise to add twists to the ladder.

    What Happened:

    You have just made a candy model of a strand of DNA. The red licorice represents the sugar deoxyribose, the black licorice represents the phosphate groups, and together they represent the sugar-phosphate backbone of DNA.

    The gummy bears represent the bases that make the code of DNA. The four different colors are used to represent the four different bases found in DNA: adenine (A), thymine (T), guanine (G), and cytosine (C). It doesn't really matter in your model how much of a base you use or where it is placed in the strand, but it is important that bases are paired up correctly: A with T and G with C. (In real DNA the order does matter as that determines what type of organism it is and how functional it will be.)

    The marshmallow in between the gummy bears represents the hydrogen bonds connecting the bases. This is the point at which the DNA strands break apart during replication and where the new strand connects to the original strand. Twisting the ladder at the top in a counterclockwise direction gives the DNA model its true shape: a right-handed double helix.

    Read more about DNA here.

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