@kellyjay said
They will continue until the material that is going to react is used up, there isn't a means by which anything will stop once what is required has been found. Unlike sunsets, if you acquire the proper chemical due to a reaction, further reactions will remove what you needed, it isn't a game where once you get what you want, and then you get to keep it indefinitely. Stupid and meaningless is your complaint.
Since biological life depends on self-replicating molecules that codify information, chemical evolution is a prerequisite to biological evolution. That is, self-replicating molecules must have evolved first, and these in time created more complex structures containing hereditary information.
Using fairly simple starting ingredients (nucleotide bases and amino acids), recent laboratory experiments have succeeded, under varying environmental conditions, in eliciting the spontaneous emergence of new self-replicating molecules. Here is a link to one of many papers on the subject:
https://pubs.acs.org/doi/10.1021/jacs.9b10796
Spontaneous Emergence of Self-Replicating Molecules Containing Nucleobases and Amino Acids
ABSTRACT
The conditions that led to the formation of the first organisms and the ways that life originates from a lifeless chemical soup are poorly understood. The recent hypothesis of “RNA-peptide coevolution” suggests that the current close relationship between amino acids and nucleobases may well have extended to the origin of life. We now show how the interplay between these compound classes can give rise to new self-replicating molecules using a dynamic combinatorial approach. We report two strategies for the fabrication of chimeric amino acid/nucleobase self-replicating macrocycles capable of exponential growth. The first one relies on mixing nucleobase- and peptide-based building blocks, where the ligation of these two gives rise to highly specific chimeric ring structures. The second one starts from peptide nucleic acid (PNA) building blocks in which nucleobases are already linked to amino acids from the start. While previously reported nucleic acid-based self-replicating systems rely on presynthesis of (short) oligonucleotide sequences, self-replication in the present systems start from units containing only a single nucleobase. Self-replication is accompanied by self-assembly, spontaneously giving rise to an ordered one-dimensional arrangement of nucleobase nanostructures.
INTRODUCTION
Establishing possible pathways through which life can emerge from inanimate matter is one of the grand challenges in today’s science. In addressing this challenge the functional and structural characteristics of present-day life provide important guidance. At the same time, the overwhelming complexity of evolved life makes it challenging to extract its essence and identify pathways for its emergence.
Recently, a systems chemistry view toward the challenges of the origins and synthesis of life is gaining popularity. The facts that many different types of molecules coexisted at the time of life’s origin and that the same applies to present-day life, warrants an exploration of what may emerge upon allowing different compound classes to interact. For example, the notion of peptides and nucleic acids cooperating during the early stages of the emergence of life is becoming increasingly popular and nucleobase-peptide chimera show unique self-assembly behavior and can give rise to remarkably complex foldamers.
Key in the transition of chemistry into biology is the acquisition of function. The core functional characteristics of life are its ability to replicate, to metabolize, and to be spatially segregated from its environment. Where life requires the functional integration of all of these characteristics, most research efforts still focus on one of these aspects in isolation.
Autocatalysis, the ability of systems (molecules, metabolic networks or compartments) to make copies of themselves, is central to all evolutionary scenarios. Systems where autocatalysis is accompanied by information transfer and heredity are said to be self-replicating. Synthetic systems of self-replicators have been pioneered by von Kiedrowski using short DNA strands. Subsequently, self-replicating molecules have been developed that feature most of the other important current biopolymers (i.e., RNA and peptides as well as completely synthetic molecules. A major issue in replicator chemistry is the tendency for self-inhibition through replicator duplex formation. This causes many replicators to exhibit only parabolic growth (i.e., showing a kinetic order in replicator of 1/2) whereas exponential growth (first order in replicator) would be necessary for most scenarios of Darwinian evolution. Another problem in replicator chemistry is the complexity of the structures associated with most self-replicators, which are unlikely to emerge spontaneously from simple starting materials.
We recently introduced a new approach to self-replication that addresses both of these problems simultaneously. This approach relies on (i) the creation of a mixture of molecules that continuously interconvert (a dynamic combinatorial library or DCL) and (ii) a self-assembly process that leads to the sequestration of molecules from this mixture, which subsequently get replenished. The combination of these two features is sufficient for the spontaneous and autocatalytic formation of self-replicating molecules. Given that networks of interconverting molecules and self-assembly processes are likely to have been widespread in prebiotic environments, this mechanism provides a likely path for the spontaneous emergence of replicators. Note that the building blocks that give rise to the network of interconverting molecules can be relatively simple, while the structure of the emerging replicators can be relatively complex, consisting of many different building blocks connected in a way that is not a priori specified. Furthermore, exponential replication is possible upon entering a growth-breakage cycle, in which mechanical energy is utilized to break replicator assemblies exposing more edges from which the assemblies grow.
A systems approach to the emergence of self-replicating molecules, where different compound classes (i.e., amino acids, peptides, and nucleobases) coexist has thus far received only little attention. Efforts directed at PNA-based replicators, in which an amino acid replaces the phosphate-sugar backbone of DNA/RNA, come closest. However, PNA remains very similar to DNA/RNA in architecture and behavior.
We now report the spontaneous emergence of new self-replicating molecules from molecular networks in which nucleobases and amino acids are both present. We show that this leads to chimeric replicators, which rely on the assembly of peptides and nucleobases into fibrous aggregates (but do not rely on base-pairing) resulting in the autocatalytic formation of a one-dimensional arrangement of nucleobases. The two different systems constructed herein allow for a direct comparison between replicator mutations. The peptide-nucleobase system shows that mutations are easily accommodated during replication, while in the PNA system, replicator mutation is impeded as it requires a change in ring size. While the building blocks used were not selected for prebiotic relevance, they do illustrate the potential of the assembly driven replication mechanism that might well extend to other types of molecules.
The bold-faced text in the last paragraph is the upshot. It is worth pointing out, I think, that
amino acids have been observed in space, some of which are alien to our biosphere, but others of which are identical to the amino acids found in terrestrial organisms. So one starting ingredient for life on Earth is floating in the hostile environs of outer space, and we should therefore not be surprised if amino acids were pervasive in the "primordial soup" of early Earth.
Are you ready for the next punchline?
https://www.sciencenews.org/article/all-of-the-bases-in-dna-and-rna-have-now-been-found-in-meteorites
Here I'll just give the title of the article and the lede: "
All of the bases in DNA and RNA have now been found in meteorites. The discovery adds to evidence that suggests life’s precursors came from space."
Thus we can see that both the nucleotide bases (i.e. nucleobases) and amino acids that the laboratory experiments reported on above used to achieve the spontaneous emergence of self-replicating molecules were in all likelihood pervasive on Earth almost as soon as it formed a crust.
Once self-replicating molecules arise, interactions between them and other molecules may be expected to give rise to new structures, and it is likely that this interplay would often mimic the predator-prey models of biological organisms to some extent. Thus the process of natural selection begins, with the environment as always exerting its own influence on the course of events...