Monday, 30th October 2017

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Spark of life

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By Scientists have worked out the equation that led to life on earth, says T.V. Jayan
  • Published 8.07.13

Science may have advanced by leaps and bounds over the centuries, but it still doesn’t have all the answers. One of the nagging questions that refuses go away is on the origin of life.

Though theories abound to explain how life originated on earth, scientists believe that life emerged from a soup of lifeless matter on early earth. The environmental conditions were just right, leading to the emergence of life from this lifeless matter.

Scientists know now with certainty how the simplest of microbes evolved into amazingly complex organisms over billions of years. What they don’t know for sure is how the mechanism by which the first set of organic molecules that subsequently became the building blocks of life was created.

In the 1960s, scientists showed that when a chemical compound called hydrogen cyanide was irradiated by the ultraviolet radiation present in sunlight, it formed a molecule called imidazole, which leads to the creation of biological compounds found in DNA and RNA. But the steps involved in this reaction were not clearly understood.

A multinational research team in Germany seems to have theoretically worked this out. “It’s very clear that this did not happen in one go but through a series of complex chemical reactions,” says Anakuthil Anoop, a chemistry researcher at the Indian Institute of Technology (IIT), Kharagpur, who was a part of the team.

Mario Barbatti and Anakuthil Anoop

Anoop joined the team, which includes scientists from Germany and the Czech Republic, by accident. “The scientists led by Mario Barbatti of the Max Planck Institut für Kohlenforschung in Germany have been trying to solve this problem for a long time. I did my postdoctoral studies from the institute. About a year ago, I was visiting the lab of my adviser Walter Thiel. During the visit, Barbatti and I had a discussion on the subject, which led to my joining the team,” Anoop says.

“This is like adding one more small piece to a big puzzle,” says a modest Barbatti of their results, which were published recently in the chemistry journal Angewandte Chemie. But this “small piece” seems to be a vital piece in the jigsaw.

What was important, Barbatti says, was to understand the constraints that existed on earth before life. “For instance, we now have a better estimate about how much sunlight the environment was receiving then: if it is too much, the molecules would be destroyed; too little, they would not be formed,” says Barbatti.

He points out that for the last 50 years or so, scientists have known that this reaction was an efficient way of producing the building blocks (known as purine precursors) for DNA and RNA. “The significance of our work is in showing in detail how this reaction happens. Our work will help recreate the physical and chemical environment present before life emerged,” Barbatti told KnowHow.

When a molecule is exposed to ultraviolet radiation, it absorbs the energy and stores it in the electrons. After sometime, this energy may be transformed into heat or thermal energy.

“In our work, we have shown that heat (or thermal energy) dissipates too quickly to allow the formation of the DNA/RNA building blocks. This implies that these molecules should be formed while the ultraviolet energy is still stored in the electrons,” says Barbatti, the main author of the paper.

Interestingly, the scientists didn’t work out all these details through lab experiments but through computer simulation. The number crunching — using what the scientists call computational chemistry — is important because it provides rare insights into different chemical reactions that are theoretically plausible, but not practically so because of the minute details involved.

Some reactions in the laboratory are so elusive that they disappear before they can be gauged, says Barbatti. Hence the need for computer simulation.

Based on such pointers, scientists can subsequently carry out experiments to check out the findings.

“The recent understanding will not only help us resolve the mystery of the origin of life on earth but also give us a handle to explore whether life can be formed in earth-like planets revolving around other stars,” says Anoop.

Anoop is confident that they have got it right. “This may help us find out the perfect recipe required for the emergence of life,” he says.