Ok... Here's another idea. Model a straight strand of DNA. Use the twist deformer to twist it into a helix. Duplicate this a few times to make a strand. Combine and mesh the mesh, then use a bend deformer on the entire mesh. I would just use the initial helix (only with more loops and longer), combine them, then use them as a single mesh, but how to use this bend deformer that everyone's talking about? Can someone tell me where I can find it, please?