Can a sewing machine stitch together DNA?

If you think that looks hard with normal-sized thread, imagine trying to sew a minuscule strand of DNA. See more ­DNA pictures.
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We don't blame you for wanting to make DNA your sewing project. After all, DNA makes up our genetic code and, as such, it wields tremendous biological power. It tells our cells what to do. When we grow two feet, as opposed to say, two flippers, it's because our cells are following the instructions encoded in our DNA. And when we develop tumors, our cells are following DNA's instructions, too.

What if you could alter your genetic code? What if it were as easy as quilting? Could you piece together the "tall" code with the "dark and handsome" code, making yourself tall, dark and handsome?

The answer is a resounding "no" for several reasons. First, as smart as geneticists are, they still haven't pinpointed most of the genes that make us tall, dark and handsome. Second, once we grow beyond being a ball of a few cells early on in development, it becomes technically very difficult to alter the DNA in all of our cells. In adults, that would require tinkering with about 100 trillion cells [source: Boal].

­There's yet another flaw in your project -- that sewing machine. If you tried to manipulate your DNA with a sewing machine, you would smash it. On average, a sewing machine's needle is about 1 millimeter in diameter [source: Schmetz]. A human chromosome's width is at least 500 times smaller [source: Campbell et al.]. In addition, DNA is actually quite fragile. It can't withstand much force without breaking. In fact, if you hung a paper clip -- one that was 50 million times lighter than the office variety -- on the end of DNA, you would break it [source: Terao].

So unless you happen to be a scientist skilled in gene therapy, you don't have the equipment or the know-how to alter your DNA. But luckily your cells do, and they stitch together DNA every day without your help. Read on to learn about nature's sewing machine.