User blog comment:Mr.Robbo/Human Chauvinism 4/@comment-2001921-20131218015147

I've just been reading through this series and I've generally been in agreement but I find myself disagreeing with every point this time :P Biology is my subject, though I dabble in everything, so it's the one I am most sure about.

DNA doesn't contain proteins or amino acids; it has a sugar-phosphate backbone and nucleotide bases, which are quite simple compounds containing pi rings and nitrogens. Perhaps you're thinking of histones which are structurally important but are not to do with information storage.

I wouldn't call cellulose more complex than DNA. I'm not sure how it is. Because of all the branching? There is barely any control over what branches to what, it's just disorder manifest in the bonds. I also have problems with treating lipids as substitutes for proteins regardless of what conditions you may put them in. If you're interested in seriously considered alternatives there may be an exclusively RNA system- though I am sceptical it can support a large enough genome for eukaryotes- and TNA, though that can't form naturally. Not being able to form naturally is a big problem with contrived fluorisilicone etc examples, too.

I've had far too many alternative biochemistry discussions for one lifetime so I won't do a piece-by-piece on the sections on water and carbon. I'll just mention enzymes, to which life owes its existence- you show me how your system can make an enzyme, and then I'll pay attention.