Beginning of Life Explained: May Come From a Mix of RNA and DNA

Up to today, the mechanisms that allowed life to begin on Earth continue to fascinate experts; it isn't easy to peer back billions of years of life. Today, evidence is growing for a new hypothesis as to how life began on the planet: a precise mix of DNA and RNA.

DNA and RNA: the Prebiotics of Life on Earth

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DNA and RNA are determinants of the genetic make-up of all biological life on the planet, with DNA acting as a genetic blueprint. While RNA is a decoder, it was earlier believed that RNA developed on the planet first, with DNA evolving years afterward. However, mounting evidence suggests that both molecules may have emerged simultaneously, heavily involved in kickstarting life on Earth.

A study in 2021 backed up the idea by explaining how a compound known as diamidophosphate, which could have predated life, can knit DNA building blocks - deoxynucleosides, into primary DNA strands.

Professor Dr. Ramanarayanan Krishnamurthy, a co-author of the study and chemist from Scripps Research, California, says that their findings are a vital step toward developing detailed chemical models of how life forms originated on Earth.

These findings add credence to the idea that DNA and RNA developed alongside each other from the same chemical reaction at the beginning of life on Earth. Additionally, it is a possible explanation for the first self-replicating molecules that could have mixed with both nucleic acids as suggested by the established RNA World hypothesis.

One of the most significant issues the hypothesis faces is how RNA alone was able to go through the self-replicating process needed. Typically, RNA requires enzymes to split.

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Studying RNA's Helping Hand to Sprout Life

So far, experts know that RNA has a helping hand in engineering life. Latest experiments show that DNA could have played a vital part. Both may have created "chimeric" molecular strands that separated more efficiently than RNA alone.

A series of lab tests conducted by researchers aimed to simulate what may have happened before life began on the planet. These experiments showed how DAP could have similarly formed basic DNA as RNA can come together from chemical blocks.

Eddy Jimenez, a co-author and chemical biologist from Scripps Research, explains that the team found that using DAP molecule to react with deoxynucleoside works better when the deoxynucleosides used aren't all the same but rather a mix of different DNA letters similar to real DNA, reports ScienceAlert.

Although we may never know whether DNA lent a helping hand to RNA to form the first lifeforms on Earth, considering these events happened billions of years ago, our understanding of the process and the mechanisms at play continue to develop.

Not only is the research useful in terms of how it relates to life's origins, but it also provides an insight into the relationship between RNA and DNA and can play host to various modern chemistry and biology applications.