Oooh this is going to eat so much of my time today! Thank you!
If I ever got a science tattoo I think that it would probably have something to do with thermodynamics, or the basic retroviral genome, or maybe that punnett square, it is cute, ooh or a catalogue of mutation types, or maybe the phylogenetic tree of a particular virus I like, maybe the uncertainty principle, or the crystal structure of the ribosome, or the three DNA helical structures...? I think I am going to run out of skin before I run out of science...
[...]but I would love to get the four bases on the back of my shoulders: AT on one side (the drawn out structures) and GC on the other side.
Then all you would need to complete the set would by ribose and deoxyribose in the middle (and maybe a few phosphates floating about) ^_^