DNA replication caught on film for the first time undermines textbooks

Shane McGlaun - Oct 30, 2017
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DNA replication caught on film for the first time undermines textbooks

The image you see here isn’t of the USS Enterprise in warp, it’s an image of DNA replication captured for the first time. The interesting part is that the replication of DNA isn’t what scientists and researchers expected. In fact, the film has undermined a great deal of what is written in textbooks.

This marks the first time that scientists have captured up-close footage of a single DNA molecule replicating itself. The footage is in real-time and shows that this particular component of life has an unexpected amount of “randomness” involved. DNA replication occurs when an enzyme known as helicase unwinds and unzips the double helix of DNA into two strands.

A second enzyme called primase then attaches what science calls a primer to the unraveled strands and then another enzyme called polymerase comes along, attaches to that primer, and adds new bases to form another double helix of DNA, thus replicating the strand. This process involves a leading strand, which winds into the double helix first and a lagging strand that follows. One long-held assumption by the scientific community was that the leading and lagging strands coordinated with each other somehow during the replication process.

The video of the act of replication has revealed no coordination at all between the strands. Interestingly, even though each strand acts independently, each DNA is somehow perfectly replicated each time. The video is of a single DNA molecule from the E. coli bacteria observed on a glass slide.

The sample is stained with a dye that sticks to the double helix, but not to a single strand. This allowed the team to follow the double helix as it formed into two new strands of DNA. Bacterial and human DNA follow the same replication process. The new footage shows completely autonomous development of strands with no coordination between them. The replication video is below.

SOURCE: Sciencealert


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