RAAAGH. That does it.
Our betters in the media apparently believe we are all too thick to appreciate the BEAUTY of SCIENCE. But you, my readers, will be Made To Understand what a genetic code is, and I will do it with knitting, cakes and spam.
Thing A. Genetic Code.
Here is the genetic code. It took thousands of exceptional scientists the entire 1950s to work out, and it isn't fully understood even now.
It's sort of a phrasebook or conversion table. In fact, the closest parallel I can think of to it is this. It's a description of how a string of information (aggtgcgatagct, or k2 p2 ssk turn) can create a product with a shape and function (an enzyme, or a sock).
The genetic code is almost identical in every single living thing: that means you and your cat and your pot plant and the bacteria eating your teeth. All those leaves and brains and hair and having-more-than-one cell fripperies are just modifications of a basic mechanism, billions of years old, for taking DNA information and making it into protein activity.
If you do not find this breathtaking then you are dead inside and you should probably stop reading this and quit your job and lead a life of solitary contemplation in a turf hut until you are capable of human feeling.
The code also turns out to have some weird quirks. Think of Morse code, which was designed for speed: the most frequently-used letters in English are represented by the shortest signals in Morse (E=. and T=-). The genetic code doesn't do that, but it does show other signs of being optimised for its purpose.
Imagine a language called Cookbookese, in which the word for raisin was zob, and the word for sultana was zop, and the word for currant was zod. It would have the advantage that if your mum were telling you a fruitcake recipe over a crackly phone line, and you misheard her, your cake would turn out OK anyway. The genetic code works like that: similar amino acids have similar "names", so an error in transcription or translation is unlikely to cause huge problems.
And remember that I said "almost identical"? There are minor variants here and there. Certain fungi and some structures inside other cells, for example, use a very slightly different code.
Researchers studying the genetic code are currently asking questions like: How did the code evolve its features? How does it ever change at all when it's so central to how life works? Are there other ways in which the code is special?
Thing B. Genome Sequence.
This link goes to a genome sequence, and here is part of another. Each is a string of letters representing the information in the DNA of a particular organism. Sequencing a genome - and if someone says "decoding" or "unscrambling" they are talking down to you - is a huge project and a big step forward, but it's not really a discovery in itself; we make the discoveries afterwards using the new information we have.
When a new genome sequence is published, we can work out what a small proportion of it means because we know the genetic code, and there'll be a bit more whose function we can take a good guess at. Other stretches of it will appear to be meaningless, or self-promoting and repetitive - the molecular equivalent of "Re: Fwd: fwd: REALLY FUNNY!!!! pass this email on to 5 friends and make their day!"
And some of it we simply don't understand at all. RPM at Evolgen has some splendid posts on genome analysis if you want to know more.
If you have grasped the concept that Thing A, a genetic code, is different from Thing B, a genome sequence, consider yourself enlightened, and pledge to swear loudly at the telly next time you hear some patronising or scientifically illiterate toshmonger get it wrong.