Space and Physics
The mitochondria are the powerhouses of the cells, and that power is created by freeing the energy stored in nutrients with a series of biochemical reactions. These are known as the citric acid cycle or Krebs cycle. It is a mystery whether this is something that life developed or if it was simply co-opted from something that did not need life to exist. Researchers have now discovered a very interesting piece of the puzzle by creating the conditions of interstellar space in the lab.
Scientists from the Centre National De La Recherche Scientifique in France and from Hawai’i have discovered that it is possible to create the molecular network that makes the Krebs cycle in conditions usually found in the space between the stars.
The process by which cells release energy from food molecules is known as respiration. This is not to be confused with breathing. Through respiration, whether using oxygen (aerobic) or without oxygen (anaerobic), the cells can break apart sugars, fats, proteins, and alcohol and use the energy to perform their duties.
Important molecules that play a role in living organisms, such as sugars and amino acids (the building blocks of proteins), have already been found in space.
The team recreated the conditions of a “dense” molecular cloud: temperature around -263°C (-441°F), in a vacuum, and irradiation by energetic particles that simulated cosmic rays. The results are the formation of a bunch of molecules from citric acid to oxaloacetate that can play a role in the Krebs cycle.
The team studied the molecules produced by using an unprecedented combination of infrared spectroscopic and chromatographic techniques. While we can’t study distant nebulae in the same way, this approach can inform how to look for these molecules out there. Finding them could help us better understand how the building blocks of life might end up on planets and even how life itself might arise.
“These results illustrate the interconnected nature of astrophysics, chemistry, and biology in the advent of evolution on early Earth and defines the connection between astrobiology and evolutionary biology,” the researchers wrote in the paper.
“Sugars and amino acids have already been cataloged to form in laboratory interstellar ices and these results expand these biomolecules to include bioenergetic material in the Krebs cycle, further supporting the possibility of life-bearing material produced in interstellar environments. The complex chemistry of these environments sheds light not only on our own evolution but opens the possibility for evolution on other worlds.”
The paper is published in the journal Proceedings of the National Academy of Sciences.
