Scientists have made a surprising discovery in the study of the origin of life, revealing the ability of RNA molecules to synthesize the building blocks of proteins with both spatial configurations. This breakthrough finding, published in the journal Nature Communications, challenges the prevailing hypothesis that the selection of left-handed amino acids was solely due to chemical factors.
Proteins, which play crucial roles in living organisms, are composed of amino acids that can exist in two mirror-image forms, similar to human hands. Interestingly, in nature, only left-handed amino acids are utilized. This phenomenon, known as homochirality, is a perplexing mystery as life theoretically could function with right-handed amino acids as well.
The DNA molecule, responsible for storing genetic information, is deemed too complex for the primitive forms of life. Hence, the hypothesis suggests that RNA, capable of storing information and participating in protein synthesis, could have preceded DNA. Termed “World RNA,” this hypothesis proposed that RNA may have guided the evolution of life towards the usage of left-handed amino acids, but recent studies have debunked this notion.
Experiments conducted by scientists sought to replicate the conditions of early Earth by studying ribozymes – RNA molecules possessing enzyme-like properties for protein synthesis. The analyses revealed that ribozymes could facilitate the formation of both left-handed and right-handed amino acids, negating any chemical advantage for one form over the other during the origin of life. This groundbreaking discovery challenges the deterministic view of the selection of left-handed amino acids and suggests that homochirality could have emerged later due to evolutionary influences.
Further exploration into the chemical composition of life not only enhances our understanding of its origins but can also shape strategies for the quest for extraterrestrial life. Ongoing research on asteroid samples, like Bennu brought back by the Osiris-REX mission, as well as future analysis of Martian materials, may provide additional insights into solving this enigmatic puzzle.