I want you to imagine your genome is right in front of you. Maybe it's a big, leatherbound tome or a crisp, new paperback. In a perfect world, you would just open the book and read it, cover to cover. But the challenge of DNA sequencing is that the current technology can't do that, yet. Instead of reading your genome cover to cover, you can only see, for example, 10 words at a time. Somehow, you have to put the story back together.
If someone gave you an envelope with the fragments of a haiku in it, you could probably paste the whole thing together all on your own. But if someone hands you a shoebox with "The Cat in the Hat" fragments instead, it might take you a bit longer to put together. And what if someone delivers you an office space filled with boxes of a hefty Stephen King novel, eh? You'd probably need alot of time and alot of help.
Bigger stories mean bigger problems. That is the challenge of sequencing a genome, in a nutshell. There are plenty of things that make the problem more difficult. For example:
- What if your "story" is a poem with repeated phrases? How do you know where to put the fragment that matches 6 different places?
- What if, instead of seeing 10 words at a time, you could see 20 but there would be lots of typos?
- What if the story is so huge it would take you several lifetimes to put together on your own?
- What if I gave you a draft copy of your story, and had you match the fragments to the draft?
- What if I gave you a roomful of interns to help?
- Or better yet, what if I gave you a roomful of computers to help?