Space recipe for life-making molecules
doi:10.1038/nindia.2013.28 Published online 20 February 2013
From computer-based models, researchers have provided new insights into how precursor molecules to DNA bases and amino acids form in interstellar medium (ISM), the space between stars filled with gas and dust clouds1.
The researchers have identified the exotic chemical processes that spawn adenine, a DNA base, and the amino acids alanine and glycine in ISM. Adenine creates the genetic code along with three other DNA bases. The genetic code contains the recipe for making proteins out of amino acids like alanine and glycine. These are key processes that paved the way for rudimentary life on primitive earth.
The ISM produces comet-like objects, most of which ultimately collapse to give birth to stars. Observational data suggest that the ISM is rich in methanol, water, carbon dioxide and even amino acids like glycine. However, no previous studies have deciphered how such amino acids and other complex molecules are born in ISM.
The researchers developed a computer-based models that mimicked the conditions of gas-grain networks in ISM at ten degrees above absolute zero temperature. They used quantum chemical simulations to pin down the processes that make precursor molecules to adenine, glycine and alanine.
They found that simplest molecules like methanol, water and hydrogen cyanide form on dust grains. The heat of cosmic rays releases these molecules into the gas phase of ISM, where they react with each other to form precursor molecules such as cyanocarbene, cyanamide, methyl isocyanate and hydroxypropaenenitrile.
"After their birth in a protostar in ISM, these biomolecules hitch a cosmic ride on comets and meteorites to seed life on a planet like Earth," says Sandip Chakrabarti, a co-author of the study.
The authors of this work are from: Indian Centre for Space Physics, S.N. Bose National Centre for Basic Sciences, and Maharaja Manindra Chandra College, Kolkata, India.