DNAbc's

I've known since high school biology classes that all DNA is made up of four different chemicals, represented by the letters A, C, G, and T.  These can be put together in different sequences, making up the genetic diversity that keeps us all from looking like Pee Wee Herman, or Jeremy Clarkson, or [insert name of goofy-looking individual here].

The science of genetic engineering involves, among many other things, the careful rearranging of these components in different ways and orders, to create various effects.  This is still fairly straightforward, at least in principle-- it's terribly difficult in practice.  In fact, genetic manipulation usually happens on a much higher level, with the addition/removal/replacement of much larger complete sequences, or even entire chromosomes (which can contain well upwards of 100,000 nucleotides, the elements built out of those basic four chemicals).  As an interesting side note, apparently scientists in 2010 created an entire artificial genome from scratch, and successfully added it to an empty cell, creating the first ever completely artificial life form¹.

At any rate, things have gotten even more complicated.  Scientists are now starting to create nucleotide analogues that can be inserted into DNA sequences, allowing for even weirder possibilities².  They might not necessarily do anything radically different from the existing ones, but if nothing else it allows for some interesting artistic possibilities.  If we can add more letters to the genetic code, we might someday get poems written in a grain of rice, or designer crops with EULAs written right into their DNA.  GATGGACTTATTCATHEUSERAGREESTOTHEFOLLOWING...

¹http://www.sciencemag.org/content/329/5987/52

²http://www.newscientist.com/article/dn13252-artificial-letters-added-to-lifes-alphabet.html