A unique demonstration model of DNA

I describe a physical demonstration model of DNA for the classroom. The model comprises two types of building block that fit together through complementary shape interactions and are held in place by magnets. These building blocks, which represent the purine and pyrimidine bases of DNA, can be put together rapidly (about a minute) to produce an abstract structure that portrays several of the gross architectural features of idealized B-DNA. Thus the model is a right-handed double helix whose strands run in opposite directions and has major and minor grooves. The blocks that form the base-pair units do so specifically. These units lie perpendicular to the helical axis, there are 10 base-pair units per turn, and any sequence can be built with them. Crucially, unlike any other demonstration model currently available, the model can be replicated in situ. It is also self-supporting. The model should complement the currently available resources for teaching the structure and function of DNA.