Scientists discover possible recipe for early life
A group of scientists believe they have discovered the chemistry that gave rise to the first instances of life on Earth.

Joseph Scalise | Apr 19, 2018

Researchers working at Scripps Research Institute have discovered a plausible way to explain how life first began on Earth, according to new researchpublished inNature Communications.

In the study, the team identifiedthe key chemical reactions behind the citric acid cycle -- the conversion of carbohydrates, fats, and proteins into the essential chemical energy used by all anaerobic organisms. They then built a list of the ingredients found on Earth some 4 billion years ago and looked at how they could spark such a cycle.

"This was a black box for us," said study co-author Ramanarayanan Krishnamurthy, an associate professor of chemistry at The Scripps Research Institute, according to International BusinessTimes. "But if you focus on the chemistry, the questions of origins of life become less daunting."

Past attempts to build a recipe for early life aimed to replicate reactions found in the modern citric acid cycle. However, the team in the study believed suchreactions were too fragile to exist on early Earth. As a result, they replicated the chemical reactions using only ingredients fromtwo non-biological chemical reactions cycles: the HKG cycle and the malonate cycle.

Both of those processes are similar to the citric acid cycle because they each have the ability to introduce a new source material into the cycle. They also feature oxidative decarboxylations, which produces carbon dioxide.

The team's models revealed that both cycles could combine to spark a primitive version of the citric acid cycle capable of generating both amino acids and CO2. That then would have produced the basic chemicals needed to kickstart life on Earth.

This finding is important because, not only does it shed light into how life began, but it also reveals thatmodern metabolisms had a non-biological precursor. There is a chance that biological molecules may haveinserted themselves into the cycle early on, but more research is needed before such claims can be made.

"The chemistry could have stayed the same over time, it was just the nature of the molecules that changed," added Krishnamurthy, according to UPI. "The molecules evolved to be more complicated over time based on what biology needed."

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