Biological molecular models often present a challenge for high quality molecular modelling. Smaller molecules can be made up and presented in the same way as for our inorganic molecules. That said, many biological and organic molecules are often quite large and, where they have, for example, long relaxed carbon chains, they lack any significant rigidity. As a consequence, the models risk being easily distorted through any kind of handling.
Where a model is highly flexible by its very nature, we offer to mount it in a way that holds and supports the molecule in its lowest energy conformation (or whatever conformation you prefer), as illustrated in many of the models here. This not only presents a chemically accurate representation of the structure, but it also results in models whose appearance reflects their high quality and accuracy.