Theoretical origin of life;a very critical essay of research (Introduction)

by David Turell , Thursday, May 07, 2020, 01:33 (1661 days ago) @ David Turell

The cause of the origin of life is totally unknown and a very diffcult nut to crack:

https://inference-review.com/article/hot-wired

"It is a commonplace of criticism that the spontaneous formation of a living system by chance is unlikely. How unlikely? Fred Hoyle put the odds at roughly 1 in 1040,000. These odds he compared to the chance of a tornado plowing through a junkyard and assembling a Boeing 747.31 Hoyle’s tornado has enjoyed an existence all its own.

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"Nature abhors low odds. This is the simple meaning of the second law of thermodynamics. With Hoyle’s 747 having lumbered down various runways, nearly all origins of life (OOL) researchers came to recognize that the appearance of the first cell could not have been a matter of sheer dumb luck. (my bold)

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"..the simplest functional cell has both lower entropy and higher energy than its prebiotic precursors, or even its building blocks. The atoms in a cell are arranged in highly specified low-entropy configurations, and they are comprised of high-energy chemical bonds. These are unnatural circumstances. Natural systems never both decrease in entropy and increase in energy—not at the same time.

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"Physicists and chemists often combine the entropy and energy of a system to form a definition of its free energy. For spontaneous processes, a change in free energy is always negative. Harold Morowitz estimated the probability that a bacterial cell might have originated through thermal fluctuations, and determined that the probability of spontaneously going from low to high, when every other system was spontaneously going from high to low, was on the order of one part in ten to the power of a hundred billion.

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"the key challenge in OOL research lies in explaining how a system could extract energy from the environment and then direct it toward increasing its internal free-energy non-transiently. England’s experiments do not address this concern, for the energy absorbed is almost immediately dissipated away. (England mentioned, not edited by me as unnecessary)

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"All cells accomplish the goal of maintaining a high-free-energy state against opposing thermodynamic forces by employing complex molecular machinery and finely tuned chemical networks to convert one form of energy from the environment into high-energy molecules. The energy from the breakdown of these energy-currency molecules is directed toward powering targeted chemical reactions. The energy coupling is accomplished through complex enzymes and other proteins comprised of information-rich amino-acid sequences.

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"In any OOL scenario, the protocell would have to generate at least this amount in the latter stages just to overcome the thermodynamic drive back toward equilibrium, and even greater amounts would be required for replication. In contrast, a leading proposal for energy production centers on proton gradients in hydrothermal vents. Experimental simulations of vents under ideal conditions only generate small quantities of possible precursors to life’s building blocks, and the corresponding power production density is on the order of 0.001 μW/g. This quantity is considerably greater than what could practically be transferred to any stage of abiogenesis, yet it is still eight orders of magnitude too small even to prevent a protocell from quickly degrading back to simple, low-energy molecules.

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"Enzymes are essential for energetically favorable reactions since most reactions are too slow to drive cellular operations. Enzymes accelerate the reactions’ turnover rates by factors typically between 10^8 and 10^10,and the increase in many cases is significantly higher. Without enzymes... This is not a plausible scenario. In addition, individual steps in the chemical pathways to synthesize life’s building blocks and then to link them together require multiple, mutually exclusive reaction conditions, so no environment could support more than a few required steps. The enzymes create the necessary nano-environments in their active sites to support their targeted reactions, so a multitude of diverse reactions can be maintained in the same cellular microenvironment simultaneously. They are required both to specify and power the correct set of processes. (my bold)

"A minimally complex free-living cell requires hundreds of tightly regulated enzyme-enabled reactions. If even one enzyme were missing, all metabolic processes would cease, and the system would head irreversibly back toward equilibrium. England’s research does not explain how such a complex, specified system could originate. Both the proteins that constitute an engine’s building blocks and enzymes represent sequences of amino acids that contain large quantities of functional information. The amino acids must be arranged in the right order in the same way the letters in a sentence must be arranged properly to convey its intended meaning. This arrangement is crucial for the chains to fold into the correct three-dimensional structures to properly perform their assigned functions. This information is essential for constructing and maintaining the cell’s structures and processes. Until origins researchers address the central role of information, the origin of life will remain shrouded in mystery."

Comment: Origin of life must be seen as a miracle, as Paul Davies has suggested.