【Beauty Salon Special Service 4】

Almost all living creatures,Beauty Salon Special Service 4 from humans to plants to germs, are created when a single DNA molecule copies itself, continuously repeating our vital genetic data.

Now you can see the amazing process for yourself.

Scientists at the University of California, Davis, captured DNA replication on video for the first time. The 11-second clip -- which kind of looks like something pulled from a 1970s video game -- shows glowing strands of DNA stretching from left to right as it duplicates.

Using sophisticated imaging technology and fluorescent dye, researchers watched a single DNA molecule from E. coli bacteria as it replicated. They also measured how quickly the process unfolded in real time.

This unprecedented view "allows you to see unusual behaviors that you wouldn't otherwise see," Stephen Kowalczykowski, one of the authors of the new DNA study published in the journal Cell, said in an interview.

A DNA double helix is made of two strands running in opposite directions. Each strand is made of four bases -- A, T, C, and G -- that pair up in specific ways to form rungs along the strands.

When a DNA molecule replicates an enzyme called "helicase" unzips the double helix into two single strands. A second enzyme attaches a "primer" to each strand, which allows them to replicate.

Then a third enzyme, "polymerase," joins the party by attaching to the primer, moving along with the growing strand and adding new letters to form another double helix.

In DNA replication, the "leading" strand forges ahead, adding letters as it goes, while the "lagging" strand follows behind, connecting the double helix in fits and starts.

Biologists widely believed these strands moved at a fixed, determined speed. But the new study shows that the process is much more erratic, and strands operate more autonomously than thought.

Replication can stop unpredictably, and speeds can vary by about ten-fold.

Kowalczykowski compared DNA replication to driving on a congested California freeway. Imagine you're driving parallel to a car in the adjacent lane.

"At some point, the car gets way ahead, and then at some point you get way ahead of that car," he said. "At the end of the hour, somehow both of you wind up more or less in the same place." That's how polymerases move in DNA replication.

Scientists also found an "emergency brake" that can automatically halt a "runaway" strand by slowing it down so the rest of the enzymes can catch up.

Kowalczykowski said the study opens up a new way of thinking about DNA replication and other biochemical processes.

"It's a real paradigm shift, and undermines a great deal of what's in the textbooks," he said in an earlier statement.