Genome complexity: DNA replication at random! (Introduction)

by David Turell , Thursday, June 22, 2017, 15:25 (2711 days ago) @ David Turell

A video of how DNA replicates changes all the concepts of how it works:

http://www.sciencealert.com/dna-replication-has-been-filmed-for-the-first-time-and-it-s...

"Here's proof of how far we've come in science - in a world-first, researchers have recorded up-close footage of a single DNA molecule replicating itself, and it's raising questions about how we assumed the process played out.

"The real-time footage has revealed that this fundamental part of life incorporates an unexpected amount of 'randomness', and it could force a major rethink into how genetic replication occurs without mutations.

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"The new genetic material that's attached to each one during the replication process is an exact match to what was on its original partner.

"So as the leading strand detaches, the enzymes add bases that are identical to those on the original lagging stand, and as the lagging strand detaches, we get material that's identical to the original leading strand.

"Scientists have long assumed that the DNA polymerases on the leading and lagging strands somehow coordinate with each other throughout the replication process, so that one does not get ahead of the other during the unravelling process and cause mutations.

"But this new footage reveals that there's no coordination at play here at all - somehow, each strand acts independently of the other, and still results in a perfect match each time.

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"The team found that on average, the speed at which the two strands replicated was about equal, but throughout the process, there were surprising stops and starts as they acted like two separate entities on their own timelines.

"Sometimes the lagging strand stopped synthesising, but the leading strand continued to grow. Other times, one strand could start replicating at 10 times its regular speed - and for seemingly no reason.

"'We've shown that there is no coordination between the strands. They are completely autonomous," Kowalczykowski says.

"The researchers also found that because of this lack of coordination, the DNA double helix has had to incorporate a 'dead man's switch', which would kick in and stop the helicase from unzipping any further so that the polymerase can catch up.

"The question now is that if these two strands "function independently" as this footage suggests, how does the unravelling double helix know how to keep things on track and minimise mutations by hitting the brakes or speeding up at the right time?

"Hopefully that's something more real-time footage like this can help scientists figure out. And it's also an important reminder that while we humans love to assume that nature has a 'plan' or a system, in reality, it's often a whole lot messier."

Comment: Accurate DNA replication is the key to life continuing, and it looks messy. But we know it can't be. All of this appeared on a rocky Earth by an unknown process. Logically, only planning by a mind can do this. I choose God.