To organize our knowledge of DNA molecules, we make pictures as if we could see them and models as if we could touch them. This allows us to store our knowledge of DNA molecules in reference frames—just like our knowledge of coffee cups. We use this trick for much of what we know. For example, we know a lot about photons, and we know a lot about our galaxy, the Milky Way. Once again, we imagine these as if we could see and touch them, and therefore we can organize the facts we know about them using the same reference-frame mechanism that we use for everyday physical objects.
