SCIENTISTS SUGGESTS THAT NEW EVIDENCE PROVES WE WERE WRONG ABOUT THE ORIGIN OF LIFE
Recent peer-reviewed research has examined the precise moment when amino acids entered the gene's evolutionary chain. Although we already know that all life forms have the same genetic code, there has been some debate among scientists regarding how and when this code originated. According to genetic scientists at the University of Arizona, our understanding of how this genetic code has evolved requires some serious amending.
In the journal Proceedings of the National Academy of Science, Sawsan Wehbi and senior author Joanna Masel presented a novel theory that significantly deviates from the general consensus of scientists regarding the sequence in which amino acids, the building blocks of genetic code, were discovered.
"The genetic code is a remarkable system that uses 20 distinct amino acids to translate codons—sequences of three nucleotides—in a string of DNA or RNA into protein sequences. Our code is surprisingly good, but the process is mind-bogglingly complex. It must have developed gradually and is almost ideal for many things. Important components of our proteins, known as amino acids, date back four billion years to the 'last universal common ancestor' of all life on Earth," the researchers explained.
The single life form that gave rise to all subsequent life forms is known as the "last universal common ancestor" (LUCA). The scientists argue that because previous research is based on lab experiments rather than evolution, it is out of date and flawed. For instance, the old theory relies on a famous 1952 Urey-Miller experiment, which attempted to imitate early Earth conditions that likely saw the origin of life, reports Phys.org.
Recent peer-reviewed research has examined the precise moment when amino acids entered the gene's evolutionary chain. Although we already know that all life forms have the same genetic code, there has been some debate among scientists regarding how and when this code originated. According to genetic scientists at the University of Arizona, our understanding of how this genetic code has evolved requires some serious amending.
In the journal Proceedings of the National Academy of Science, Sawsan Wehbi and senior author Joanna Masel presented a novel theory that significantly deviates from the general consensus of scientists regarding the sequence in which amino acids, the building blocks of genetic code, were discovered.
"The genetic code is a remarkable system that uses 20 distinct amino acids to translate codons—sequences of three nucleotides—in a string of DNA or RNA into protein sequences. Our code is surprisingly good, but the process is mind-bogglingly complex. It must have developed gradually and is almost ideal for many things. Important components of our proteins, known as amino acids, date back four billion years to the 'last universal common ancestor' of all life on Earth," the researchers explained.
The single life form that gave rise to all subsequent life forms is known as the "last universal common ancestor" (LUCA). The scientists argue that because previous research is based on lab experiments rather than evolution, it is out of date and flawed. For instance, the old theory relies on a famous 1952 Urey-Miller experiment, which attempted to imitate early Earth conditions that likely saw the origin of life, reports Phys.org.
Even though sulfur was abundant on Earth in its early years, such experiments failed to find amino acids that contained sulfur. Therefore, it may not be accurate to assume that sulfuric amino acids were later added to the genetic code. The team proposed rethinking the order in which the 20 amino acids emerged by creating a tree of protein domains to the LUCA, which was not discovered until the 1970s, using data from the National Center for Biotechnology Information and current technology.
Wehbi clarified: "A domain is comparable to a wheel if you consider the protein to be a car. Wheels have existed for a lot longer than cars, and this part can be used in a variety of cars."
In essence, the team found that the genetic code of today probably evolved after other codes that became extinct. More than 400 protein sequence families that predate LUCA were found by them; more than 100 of these families had already undergone diversification and originated even earlier than LUCA. There were more amino acids with aromatic ring structures in these sequences.
"This provides clues about other genetic codes that preceded ours and have since vanished in the depths of geologic time," Masel continued. "It appears that early life enjoyed rings."