DNA polymerase

"A DNA polymerase is a cellular or viral polymerase enzyme that synthesizes DNA molecules from their nucleotide building blocks."
-http://en.wikipedia.org/wiki/DNA_polymerase

This model is a surface representation of the crystal structure of the catalytic alpha subunit of E. coli replicative DNA polymerase III. Based on PDB entry 2HNH:
http://www.rcsb.org/pdb/explore/explore.do?structureId=2hnh

STL file created using VMD:
http://www.ks.uiuc.edu/Research/vmd/