Theoretical origin of life: a woolly math approach (Introduction)

by David Turell @, Wednesday, November 24, 2021, 19:55 (10 days ago) @ David Turell

A far-out paper assuming heat production guided by inherited information that seems to appear out of nowhere:

https://www.quantamagazine.org/at-the-dawn-of-life-heat-may-have-driven-cell-division-2...

"An elegant ballet of proteins enables modern cells to replicate themselves. During cell division, structural proteins and enzymes coordinate the duplication of DNA, the division of a cell’s cytoplasmic contents, and the cinching of the membrane that cleaves the cell. Getting these processes right is crucial because errors can lead to daughter cells that are abnormal or unviable.

"Billions of years ago, the same challenge must have faced the first self-organizing membranous bundles of chemicals arising spontaneously from inanimate materials. But these protocells almost certainly had to replicate without relying on large proteins. How they did it is a key question for astrobiologists and biochemists studying the origins of life.

“'If you delete all enzymes in the cell, nothing happens. They’re just inert sacks,” said Anna Wang, an astrobiologist at the University of New South Wales in Sydney. “They’re really stable, and that’s kind of the point.”

***

"Attal thinks that that the chemical and physical processes active in early life were probably quite simple, and that thermodynamics alone could therefore have played a significant role in how life began. He said that the kinds of basic equations he has been working on could spell out some of the rules that governed how life first emerged.

***

"For primitive cells to divide themselves without complex protein machinery, the process would have needed a physical or chemical driver. “It’s really about stripping a cell down to its basic functions and thinking, ‘What are the basic physical and chemical principles, and how can we mimic that without proteins?’” Wang said.

***

"What scientists do agree on is that protocells must have had some kind of heritable information they could pass down to daughter cells, a metabolism that carried out chemical reactions, and a lipid membrane isolating the metabolism and heritable information from the randomness in the rest of Earth’s primordial soup. Whereas the outside chemical world was inherently random, the partitioning provided by the lipid membrane could create an area of lower entropy. (my bold)

***

"Attal realized that the energy produced by the primitive cellular metabolism would heat up the lipids on the inside of the membrane more quickly than those on the outside. Thermodynamics would then force the energetic inner lipids to “flip” to the outside, causing the outer membrane layer to expand at the expense of the inner layer. One easy solution to this imbalance would be for the cell to pinch together into two daughter cells. This pinching would occur at the middle of the parent cell, where it was hottest and the lipid movements were most pronounced.

[There follows a large series of objections from others]

"Neither of these issues means that heat didn’t play a role in early cell division, only that Attal’s mathematical model may not be the most accurate, Wang says. Still, Claudia Bonfio, a biochemist at the University of Strasbourg in France, says that the paper adds to the literature on early life because “it’s a nice starting point for experiments. We too often forget that reactions consume and produce heat, which could have an effect on things like fission.'”

Comment: note in the bold the miraculous appearance of necessary parts of the protocell. The obvious objections were quite strong, but note the final paragraph trying to justify this foolishness.


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