DNA or RNA - which would you choose?
So you're in the market for an information storage molecule. You'd like something functional and compact, runs on regular gas, and doesn't cause cancer in rats.
A quick scan down the options, what is there out there that you could base a species on?
DNA
At the top of the popularity list is DNA. No one ever got fired for choosing DNA, DNA is a the choice of the masses. Its used by 99.9999% or so of all known organisms. Its the safe choice, its the sensible choice, its the boring choice.
RNA
However, maybe you aren't one to follow the pack, maybe you like to dabble a little in stuff thats not run of the mill. RNA at number two in the list might suit you. Its not the popular choice, but other organisms have made a go of it, so maybe you can too.
Others
If your really into the exotic, you can go with untried and untested types, PNA, GNA, TNA might work for you, but you can't get them off the shelf, you'll have to make those yourself.
Choosing RNA
So - how about choosing RNA as your hereditary molecule? Its got a lot going for it. It can replicate, its already used to make proteins, its got any number of jobs around the cell. Its also pretty fast - only one strand to replicate, and the base it uses U is probably less expensive to make than the regular T.
However, RNA has its down sides too. Sure, its cheap to make, and allows you to live life in the fast lane, but its not very stable - too much wild living. When its not busy doing other things, or involved with other molecules, it likes to attack itself.
Its also a little shoddy when it comes to replication. It figures close is good enough. It mostly copies itself ok, but it slips up now and again, perhaps a little more frequently than you'd like.
Choosing DNA
DNA may be the old codger, but there is a reason most organisms go for DNA when looking for something to encode their lifes work. So its not as fast and loose as RNA, but at least it tends to keep what it started off as. Sure it may take a little longer to copy, but thats partly because it keeps checking itself to see if its doing it right. It will also stand back, and compare its second strand with the newly copied strand - just to check things are going on ok.
DNA requires a whole load of support infrastructure though, so you are probably going to need a package deal. You'll probably need to buy the copying, repairing and checking bits separately if they are not included in the main package - check the small print.
