Researchers confirmed that key DNA components exist in extraterrestrial meteorites. Meteorites revealed amino acids which make up proteins, essential building blocks of life that could have been an important source of the organic compounds of life on Earth. 

In addition, the discovery by another team of molecules linked with a vital ancient biological process, supports scientists' theory that life on planet Earth could have started from components from outer space.

Researchers discovered molecules that make up building blocks of a vital biological pathway, the citric acid cycle, in a number of organic-rich meteorites.

The citric acid cycle is "thought by many experts to be among the most ancient of biological processes," said study co-author and NASA chemist George Cooper. "One function of this cycle is respiration, when organisms give off carbon dioxide."

"It is always exciting to find extraterrestrial and ancient 4.6 billion-year-old organic compounds that might have had a role in early life," Cooper added.

The findings were published online in the Proceedings of the National Academy of Sciences.