StephanWatkins

some plants you can freeze and save cuttings which germinate, others not. You can however save any plants cells by isolation of single cells in solution, you can look up the protocols in protocol books, and freezing these suspensions in 5-10% DMSO PBS buffer, or variant, 5% Glycerine, 5% DMSO PBS, and 20% Glycerine PBS (with a much lower survival rate) work from experience. These cells, turned into protoplast can theen be germinated using a petri dish hormone -> Callus -> root and shoot hormone protocol, or alternativly turned from callus -> gymnosperm like synthetic seeds which only have a 5-30% germination rate based on the individual plants. The synthetic seed protocol has been used in industry, and involves a waxlike calcium carbonate cellulose mixture again with rooting and shoot formation hormones that micro calluses are dipped into and then dried, only 2-3 hormones in total. The petri dish method is a, or is the main method for a large scale orchid market in the US, and several individual plant companies with individual plants in Holland.

Interestingly I have done many simulations of DNA and RNA and thought the question warrants more than the generic answer. In general, like CharonY points out, the actual space filled by all the atoms leaves very little room, however there are ions that fill in the grooves some times transiently, mostly K, Ca2+, Na and Mg2+ is like a magnet. High concentrations of Mg2+, non-natural actually cause DNA cleavage with nothing other than water. Overall the structure is very fluid, think of it as having small ripples that move down either strand constantly. Aside from this, there are several natural nucleotide analogous, uricil for instance in RNA can also be incorporated but rarely, usually only from a diseased state. But there are a wide range of synthetic DNA like molecules, where the sugars or backbone phosphates have been replaced, such as PNA (protein nucleic acids), or modified sugars, but these are all synthetic as mentioned. There are some pathogens that work by modifying DNA into Urcil, or derivative nucleic acids through cytosine mostly, or thymadine. There are also many compounds that work by intercalation between nucleotides, most cause cancer. An example most used is ethidium bromide, used in labs to see DNA in agar gels, where the molecule exploits the kinetic movements I mentioned, and works it's way in between base pair stacks.