This is a small model of DNA, about 5cm long and the resolution of atoms is still very good. It is represented by VDW spheres coloured according to atom type.
DNA encodes genetic information in a chain of nucleotides. This structure includes a short DNA double helix sixteen nucleotides long.
PDB: 3BSE http://www.rcsb.org/pdb/explore/explore.do?structureId=3bse
For a larger DNA model see http://shpws.me/oWPl