When firstly creating this model of DNA i made it from a single plane. The image on the left shows the plane being modified into a lattice. This seperates all the segments of the plane up into tetra shapes. It also gives the user the option of choosing tetra, octa or icosa ends to the segments. These are the pyrmaid shape things on running down the edges of the model.
In order to make these more DNA like i chose tetra joints and put around 50 sides to make them spherical in shape, along with a radius of about 5.
When modifying the struts that run from edge to edge, i chose a large number of edges so that it make them cylindrical and more life like, with a small radius.
The next steps i took were to twist the model into a DNA-like structure. I did this by applying the twist modification. Once that was done i then moved the twist modifcation above the lattice in the modifying list. This twisted the actual lattice instead everything that the model consisted of.
The final part of the model was to create a material that mapped the effect of DNA. I did this by using a falloff in the "Diffuse colour" section, and then selecting various colours to make a kind of gooey DNA effect. To make it more realistic i used the bump map and selected "Mix". This allowed me to use 2 different effects together, such as noise and cellular.
Once these were mixed it was just a case of playing about to get the required texture on the model.
Last but not least i used a simple JPEG image as the background of the final rendered model. Then it was just a case of finding the appropriate angle and screenshot for which will be the final render the my DNA model :D