The Biggest Piece Of DNA Ever Made

An anonymous reader writes "Forbes has a story on 'the biggest piece of artificial DNA ever made'. The real story is that companies are racing to produce longer and longer DNA fragments to serve the growing science of synthetic biology." From the article: "On a piece of DNA as long as the one made for Microbia, ten or more genes may be present. By studying more than one gene at once, researchers hope to get a better picture of how they work in concert to produce an organism. Another advantage: These stretches can also be made to contain all the DNA letters that occur between genes. Scientists once thought of that stuff as junk, but many now believe it may regulate how the genes work or provide some other function."

27000 "letters" long?

[yams69]

How about "bases" or "base pairs"? Are they creating a string, or DNA? Granted, Forbes ain't a science rag, but still...let's show our readers we took some high school biology.

Re:"junk" DNA

[ultramk]

The argument you're making isn't a new one, but the main piece of evidence against it is pretty compelling. "Genetic drift" is a phenomena where over time, random mutations add up to change areas of DNA. The thing is, if the DNA in an area is used for something that is important to keep the organism alive (or gives some sort of reproductive advantage), it can't take too many changes or the organism will die (or not be able to reproduce, very much the same thing from an evolutionary standpoint). So you get some areas where there are lots of changes, and areas where there are essentially no changes.

Picture it this way, you have a fleet of 500 Geo Metros starting out in Kuwait City, with direction to drive north to Turkey through Iraq. The whole time, guys with AK47's are taking pot shots at them (random mutations). For the ones who get all the way to Turkey, you'll find that none of them have sustained major damage to their engines/coolant systems/drivetrain/tires (because if they had, they wouldn't have made it this far). This is one way of identifying what's important to the functioning of the organism. You can drive without windows or an air conditioner, but without a transmission you're screwed.

Beware the tendency of the uneducated to assume that people who devote their lives to a subject haven't considered the most basic of possibilities. It's simple hubris.

m-

Re:"junk" DNA

[14CharUsername]

Isn't that kinda what he's saying? The extra DNS means that a mutation results in an altered species that may or may not be viable. If it weren't for the extra DNA the result would be dead offspring, which doesn't help evolution any. Mutations are random, which means they can be good (opposable thumb), bad (various genetic problems) or ugly (superfluous nipples). What makes a mutation ugly is subjective. What makes a mutation good or bad is decided by natural selection. Most mutations will fall into the bad and ugly categories, so yeah it seems like mutation is a bad thing. But a mutation is sometimes just enough to avoid extinction.

Re:exons/introns

[smellsofbikes]

A lot of the junk in there IS junk -- detritus from long-past viruses and stuff like that. A lot of it we have no idea. Some of it is clearly regulatory. Now we're beginning to get reliable tools that tell us which is which.
I just think the summary is misleading in the same way that an extron/intron duality implies: it says that there are two categories of DNA, expressed DNA and junk. That's clearly not true, and it's been known for 50 years that that's not true. The big question is exactly how not true, and with stuff like this we can begin to answer that question.
I'm going to be unsurprised if we find that the majority of intron material is useful at a lower information density than exons. Maybe stuff in there somehow determines how the circulatory, nerve, and lymphatic systems route through the body, or governs parts of apoptosis. There's a *lot* of developmental information we haven't begun to track down yet and that seems a likely place for it to be stored.