What is the recipe of life? No one knows for sure how, or exactly when, (or even where, if here on Earth or elsewhere in the vast universe) a series of chemical reactions gave rise to the first forms of life. But now, a joint research by the University of North Carolina and the University of Auckland has developed a new hypothesis, which exposes in detail how life was cooked.
According to the article published in the journal Molecular Biology and Evolution, life originated and n perfect harmony between nucleic acid (genetic instructions for all organisms) and proteins called peptides (binding of several amino acids) RNA.
And, why is this conclusion innovative? It contradicts the hypothesis most widely accepted by scientists; nevertheless, it relies on solid laboratory tests.
Until now, most scientists agreed that life originated from nucleic acids, and that it later evolved including proteins, which is called the RNA world hypothesis. Instead, the new hypothesis states that this ‘small protein’ (RNA peptide) was already part of the primordial broth that gave rise to life, which has been called the RNA peptide hypothesis.
“Until now, it was thought that it was impossible to carry out experiments to penetrate the origins of genetics,” according to one of the main authors of the study, Dr. Charles Carter, professor of biochemistry and biophysics. “But now we have shown that the experimental results combine very well with the RNA peptide hypothesis, and these experiments provide quite convincing answers to what happened at the beginning of life on Earth.”
According to the researchers, these ‘superfamilies’ of enzymes, the peptides, possess special attributes; These attributes allow them to establish a feedback system with the first genes, which would have driven early biology and early life forms, leading to the diversity and complexity that multicellular organisms make possible.
As shown by Professor Carter’s laboratory tests, the ancestors of these peptide families would be encoded by complementary strands. An arrangement that is quite simple, with an initial code of only two amino acids. This simplicity suggests that this structure must have occurred at a very early stage of biology , at the dawn of it.
“These interdependent peptides and the nucleic acids that encode them could have helped each other to molecular self-organization despite the constant random interruptions that affect all molecular processes,” explains Carter. “We believe that this is what gave rise to a world of RNA peptide early in the history of life on Earth.”
The shortcomings of the RNA world hypothesis
The RNA world hypothesis, the most commonly accepted on biogenesis in the scientific community brings with it certain insufficiencies and irresolvable problems that the new hypothesis of the RNA peptide would sweep at a stroke. Moreover, for Professor Wills, another of the main authors of the study, his is “a much simpler and more probable theory of the origin of life“.
The main lack of the widely accepted theory of the RNA world is that it remains a mystery how the building blocks of amino acids (proteins ) were assembled for the first time. It is postulated that RNA, the molecule that currently performs functions in the coding, regulation and expression of genes, arose from this primordial soup of amino acids and cosmic chemicals, and finally gave rise first to short proteins called peptides, and then to unicellular organisms. .
But Carter and Wills argue that RNA cannot drive this process on its own, since it lacks a property they call “reflexivity.” RNA needed peptides to form the reflective feedback loop necessary to eventually lead to life forms.
Therefore, according to them, at the beginning, there were peptides…