DNA has been around for billions of years — but that doesn't mean scientists can't make it better. When Steven Benner set out to re-engineer genetic molecules, he didn't think much of DNA. “The first thing you realize is that it is a stupid design,” says Benner, a biological chemist at the Foundation for Applied Molecular Evolution in Gainesville, Florida.
Take DNA's backbone, which contains repeating, negatively charged phosphate groups. Because negative charges repel each other, this feature should make it harder for two DNA strands to stick together in a double helix. Then there are the two types of base-pairing: adenine (A) to thymine (T) and cytosine (C) to guanine (G). Both pairs are held together by hydrogen bonds, but those bonds are weak and easily broken up by water, something that the cell is full of. “You're trusting your valuable genetic inheritance that you're sending on to your children to hydrogen bonds in water?” says Benner. “If you were a chemist setting out to design this thing, you wouldn't do it this way at all.”
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