Abstract: A model for representing nucleic acid molecules, such as deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) consists of a plurality of helical segments secured together in end to end relation in the form of one or two helixes comprising the molecular backbone. Each of the helical segments is proportioned in length and helical curvature to be a model of the backbone units of the DNA and RNA molecules. Each unit has a flat planar member extending from the mid portion thereof which has a shape corresponding to one of the bases found in each of the separate nucleotides. Means are provided for securing the bases on opposing nucleotides together to hold a pair of helical molecular backbones together, with the helical segments and planar members illustrating the size, proportions, and relationship in the molecule in the various nucleotides.