Theoretical origin of life; from dividing droplets (Introduction)

by David Turell , Friday, January 20, 2017, 21:11 (2864 days ago) @ David Turell

It is fine thatt one can make dividing droplets, but how about the machinery inside?

https://www.quantamagazine.org/20170119-active-droplets-cell-division/?utm_source=Quant...

"The scientists studied the physics of “chemically active” droplets, which cycle chemicals in and out of the surrounding fluid, and discovered that these droplets tend to grow to cell size and divide, just like cells. This “active droplet” behavior differs from the passive and more familiar tendencies of oil droplets in water, which glom together into bigger and bigger droplets without ever dividing.

"If chemically active droplets can grow to a set size and divide of their own accord, then “it makes it more plausible that there could have been spontaneous emergence of life from nonliving soup,” said Frank Jülicher, a biophysicist in Dresden and a co-author of the new paper.

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"David Deamer, a biochemist at the University of California, Santa Cruz, and a longtime champion of the membrane-first hypothesis, argues that while the newfound mechanism of droplet division is interesting, its relevance to the origin of life remains to be seen. The mechanism is a far cry, he noted, from the complicated, multistep process by which modern cells divide.

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"Tang’s lab synthesizes artificial cells made of polymers, lipids and proteins that resemble biochemical molecules. Over the next few months, she and her team will look for division of liquid droplets made of polymers that are physically similar to the proteins in P granules and centrosomes. The next step, which will be made in collaboration with Hyman’s lab, is to try to observe centrosomes or other biological droplets dividing, and to determine if they utilize the mechanism identified in the paper by Zwicker and colleagues. “That would be a big deal,” said Giomi, the Leiden biophysicist.

"When Deamer, the membrane-first proponent, read the new paper, he recalled having once observed something like the predicted behavior in hydrocarbon droplets he had extracted from a meteorite. When he illuminated the droplets in near-ultraviolet light, they began moving and dividing. (He sent footage of the phenomenon to Jülicher.) Nonetheless, Deamer isn’t convinced of the effect’s significance. “There is no obvious way for the mechanism of division they reported to evolve into the complex process by which living cells actually divide,” he said.

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"The luckiest part of the whole process, in Jülicher’s opinion, was not that droplets turned into cells, but that the first droplet — our globule ancestor — formed to begin with. Droplets require a lot of chemical material to spontaneously arise or “nucleate,” and it’s unclear how so many of the right complex macromolecules could have accumulated in the primordial soup to make it happen. But then again, Jülicher said, there was a lot of soup, and it was stewing for eons.

“'It’s a very rare event. You have to wait a long time for it to happen,” he said. “And once it happens, then the next things happen more easily, and more systematically.'”

Comment: Hope springs eternal. to much grant money chasing too few good ideas. I am with Deamer. So droplets can be made to subdivide, but hw do they get filled with the right reactive molecules? Nuts!