A self-assembly molecular model of either a 12-layer (1 turn) or 22-layer (2 turns) double helix of DNA (deoxyribonucleic acid), with abstract-shaped parts designed to represent the nitrogenous bases, pentagonal sugar and pyramidal phosphate components needed to make a double-helix model of DNA. The three hydrogen bonds that connect Cytosine to Guanine and the two that connect Thymine to Adenine are represented by the appropriate number of pegs. The approximate scale is 1cm = 2 Angstroms. The models can be displayed as a helix on the stand (included) or unzipped into a ladder form to demonstrate the process of replication.. Supplied with full instructions. Approximate height when assembled: 24cm (12 layer model) or 44cm (22 layer model).