The origin of life has mystified scientists for a long time and several hypotheses are still on debate. A recent discovery by chemists at Scripps Research Institute demonstrated a new field of vision on how life originated on earth.
The commonly accepted hypothesis about the origin of life on earth is the “RNA World” put forward by Alexander Rich in 1962. He proposed that RNA appeared first followed by proteins and DNA successively during the evolution of life on Earth. A contradictory hypothesis is that a mix of both DNA and RNA was the first form of life. This new study provides the latest findings to support the claim.
The study was led by Dr. Ramanarayanan Krishnamurthy, an associate professor of chemistry at Scripps Research Institute, and was published in the journal Angewandte Chemie in December 2020. He said that this discovery is a vital step in developing a detailed chemical model of how life first began on earth.
The “RNA World” theory suggests that RNA came first and its replication and more complex processes led to the development of DNA. To replicate, RNA needs to separate into two strands. But, RNA is incapable of doing so on their own. Enzymes (proteins) enable RNA replication in modern organisms but in an era where proteins didn’t yet exist, this would not have been possible. Researchers say that it leads to the fact that RNA might be too “sticky” to be identified as the first self-replicators.
A strand known as “chimeric” made of both DNA and RNA, has been found to be less “sticky” and therefore, not vulnerable to this problem. Earlier studies by chemists have shown that building blocks of RNA and DNA – ribonucleoside and deoxynucleoside – could have emerged from similar chemical conditions on earth. Moreover, the new study showed that DAP (Diamidophosphate) might have played a crucial role in modifying deoxrynucleosides to form DNA strands. The same results were confirmed for ribonucleosides in 2017.
Therefore, this scenario points to a co-existence of DNA and RNA from the very beginning.
The results found by this work have broader applications in health and industry. Polymerase chain reaction (PCR) tests count on fragile enzymes for the artificial synthesis of DNA and RNA. These findings shed light on alternative, enzyme-free chemical methods that would be better appealing for the global business.