One of the prevailing theories explaining the origins of life on Earth rests on the premise that simple molecules or monomers combined together in a primordial soup to form more complex polymer chains, which eventually developed a self-replicating mechanism that eventually led to the formation of the first organisms.
However, in spite of decades of research, no study has been able to explain the exact chemical process of how simple molecules were able to transition into self-replication. This is what two scientists have attempted to demonstrate in a new model that shows how self-replication emerged, according to Brookhaven National Laboratory.
Computational biologist Sergei Maslov from the Brookhaven National Laboratory and scientist Alexei Tkachenko from Brookhaven's Center for Functional Nanomaterials used a conceptual approach in creating a model that explains how simple molecules made the leap to become complex polymers.
Their study, which was entitled "Spontaneous emergence of autocatalytic information-coding polymers" and published July 28 in The Journal of Chemical Physics, features a model that has "day" and "night" phases. In the "day" phase, individual polymers freely float, while in the "night" phase, these polymers join together through a mechanism called template-assisted ligation.
The two phases are influenced by cyclic environmental changes like temperature and pH, factors that bring the system to inequilibrium, causing the polymers to either join together or break apart. The template strand allows the polymer to reassemble itself exactly as it was during the previous "night" phase. This means the polymer can pass information about itself from one generation to the next, according to Phys.Org.
"The way our system replicates from one day cycle to the next is that it preserves a memory of what was there. It's relatively easy to make lots of long polymers, but they will have no memory. The template provides the memory," said Maslov.
"Right now, we are solving the problem of how to get long polymer chains capable of memory transmission from one unit to another to select a small subset of polymers out of an astronomically large number of solutions," he added, according to Brookhaven National Laboratory.
The model also demonstrated that it is possible for self-replication to happen even with just the template-assisted ligation.
"What we have demonstrated for the first time is that even if all you have is template-assisted ligation, you can still bootstrap the system out of primordial soup," said Maslov.
However, Maslov and Tkachenko's model has limitations, one of which is that it assumes all polymer sequences are "equally likely to occur."
"The model, by design, is very general," said Maslov. "We're not trying to address the question of what this primordial soup of monomers is coming from."
Maslov and Tkachenko's model presently lines up with the famous RNA world hypothesis, which says that life on earth started with autocatalytic RNA molecules that gave way to form the more complex DNA molecule that has the ability to transmit information to future generations, according to Phys.Org.
