I've seen these DNA strands done in several ways in print and braille. I will attach a couple of examples of how you could approach them. Often, when there are several of these in a textbook, they shown a graphic for the first couple and then revert to using just the letters. Even if your book doesn't do this, if there are many of these strands, you could consider doing the same in braille with a TN of explanation. Since, the pattern of how they join varies from one book to another, I don't think that you have to replicate it exactly -- a simplified version (pointed and rounded) would be less cluttered and easier to read. I have also seen them done with the capital letter sign omitted (and described in a TN), to simplify the graphic.
I didn't create these examples, but pulled them from some that have been done previously at my office.
I have 3 pdf files to attach, and I'm not sure how many will fit within the allowable file size for posting. (If necessary, I will e-mail them to you privately.)
Thanks for posting your question. I hope this helps ... Good luck!
edited by betty.marshall on 3/19/2010