The Fuddlebrook DNA Model

Sherry Cook Experiment Tutorial

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Blog Materials

• Two pieces of red licorice (Twizzler®)
• Four toothpicks
• Two mini pink marshmallows
• Two mini yellow marshmallows
• Two mini orange marshmallows
• Two mini green marshmallows
• Index card
• Marker


To demonstrate how chemical bases are paired in DNA


Step 1
There are four chemical bases in DNA:  Adenine (A), Cytosine (C), Guanine (G), and Thymine (T).  Adenine (A) always pairs with Thymine (T) and Cytosine (C) always pairs with Guanine (G). Use the index card to write the following key:  Adenine (A)= green, Thymine (T)= pink, Cytosine (C)=yellow, and Guanine (G)=orange.

blog 2
Put one pink marshmallow on one of the toothpicks. Next, put one yellow marshmallow on another toothpick. Repeat these steps with the additional toothpicks and green and orange marshmallows. Now each toothpick has a different color of marshmallow on it.

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Using the key you prepared, pair the correct color of marshmallow with its match on the toothpick. Pink pairs go with green and yellow pairs go with orange.

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Attach each end of the toothpicks onto the Twizzlers® (backbone) so the model looks like a ladder. Twist one Twizzler® over the other to create a twisted ladder or double helix.

DNA stands for deoxyribonucleic acid. It holds a code for every cell in the body. DNA looks like a twisted ladder when it is isolated from a cell. The sides of the DNA ladder are called the backbone and the rungs of the ladder are pairs of small chemicals referred to as bases. DNA is the “instruction manual” for the cells in living organisms. There are more than 200 cell types in the body and DNA tells each cell type what job to do. DNA stays very busy managing all of these cells!