DNA Modeling Activity
Developed by the Science Museum of Minnesota, Susan Fleming
- modeling clay (golf ball size)
- pipe cleaners (two per person)
- plastic straws (two per person)
- pipe cleaner cut into 2 inch pieces (six per person)
- plastic straws cut into 1.5 inch pieces (six per person)
- 10-20 beads (4 different colors)
- Slide the small straw pieces over each two-inch piece of pipe cleaner. Both ends of the pipe cleaner should stick out.
The structure of DNA is like a twisted ladder and the pipe cleaners/straws will make up the rungs of this ladder.
- Assign a chemical name to the four different colors of beads. One color should represent the chemical base A (adenine), another color for T (thymine), a different color for G (guanine) and C (cytosine).
In double stranded DNA, A is always paired with T, and G is always paired with C. These two base pairs are always found across from each other on opposite sides of the ladder or two DNA strands.
- Slide your beads onto open ends of the small pipe cleaners/straws. Pair your beads so that A is always across from T, and G is always across from C.
- Attach the bead end of each rung to the two long pieces of pipe cleaner making a structure that resembles a ladder.
The two long pieces of pipe cleaner represent the backbone of the DNA ladder. This backbone is composed of chemicals (phosphates and sugars) linked together to form a very long chain. The chemical bases are hung from the backbone like beads on a string.
- Flatten the modeling clay to create a base for the DNA molecule. Push the ends of the two pipe cleaners into the base so that the structure stands up.
- Crimp the end of one straw and slide this end into the open end of the other straw. Push the two straws together until they overlap about a half an inch.
- Center the straw into the middle of the DNA model. Push the straw into the clay so that the straw helps support the DNA structure. Give the model a twist and tape in place. This helps to demonstrate that DNA has a twisted or helical structure.
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