Thursday, April 1, 2010

The Intron--Nature's April Fools Joke?

So in the last post I indicated that I wouldn't be posting for a while. I suppose that wasn't true--I just hate wasting my time, and at this moment I am rather restricted in what productive operations my excited fingers can bring forth.

Let us cozy up in a tree outside your dorm room and discuss DNA, that vast library that determines what you are and some believe, to some extent, who you are. Such a vast, vast library--if one of the haploid chromosomes within your cells, one of the "stacks" if you will of the library, were to be laid out end to end, the resulting string would be taller than you (unless you're more than 2 meters tall). We call the books, the instructions for the proteins that arduously manage your entire existence, exons. Strangely enough, only about one percent of the pages in your library are books--exons. They are buried within long chains of non-coding sections, and then even within and between all the books lies shelves and shelves of gooblygunk.

These gooblygunks, seemingly random strings of letters, are called introns. I have heard people say they are evidence of species-to-species evolution because they are useless. Since they do not code for anything, they must be left-overs from our distant past, before all the mutations that made us human, that haven't been deleted yet. I had the pleasure recently of discovering that introns actually serve a legitimate purpose.

Your genes are intensely regulated to ensure that you only read and copy ("transcribe") the "books" that you need for each moment. It would be silly and possibly dangerous if you JUST needed an organic chemistry book, but someone threw the entire physics section at you, too. To prevent this, your genes have switches that turn reading on and off for each exon. You have switches to modulate HOW MUCH you read, too. They even have switches that send messengers to flip switches to turn reading on or off. It turns out that a lot of your switches that are controlled by other switches are written into the introns.

Let me just take a moment to totally praise God for this. He is so clearly showing us that just because you don't see use for something doesn't mean it doesn't have a purpose. I will go farther and say that many times, things that are useless are absolutely bursting with infinite purpose. So judge not, for "whatever you do, whether you eat or drink, do it all for the Lord Jesus Christ." Remember that verse? All things can be a glorious expression of worship...all introns may hold a deep message that we have simply overlooked.

Intron/Exon information from my BME 2104 class at UVA, taught by William Guilford