To build a simple DNA model, make a double helix shape with beads, their color corresponding to the basic constituents of a DNA molecule: phosphate, sugar and base. Follow the correct order of how the parts of the DNA molecule are connected to each other.
The construction block for the DNA molecule is called a nucleotide. It consists of a sugar molecule, a phosphate group and one of the nucleobases. There are four of these: adenine, abbreviated as A, guanine (G), cytosine (C) and thymine (T). Nucleobases constitute the steps on the spiral ladder, which is the shape of the DNA molecule. Each step is a pair of bases. Guanine only pairs with cytosine, and adenine only with thymine. The sides of the double helix ladder consist of alternating phosphate groups and sugar molecules.
- Assemble the bead structure Choose beads of different colors that can be connected to each other one by one. Assign a role to each color of beads. For instance, white beads can represent the sugar molecules, and red beads the phosphate groups. Pick four more colors for the nucleobases. Assemble several nucleotides by first joining a phosphate group and a sugar molecule, and then attaching one of the bases to them. Make two rows in which sugar molecules and phosphate groups alternate. Connect the two rows by their nucleobases, keeping in mind that only A-T and G-C pairs are possible.
- Complete the spiral ladder Holding the bead structure by the ends, gently twist it into the shape a double helix.