A Jumpstart for Biochemistry

RNA can replicate in conditions that could be found on the early Earth, suggesting a possible step in the origin of life.

https://physics.aps.org/articles/v13/117

One theory for the origin of life proposes that the initial biochemical steps were taken by RNA, a molecular cousin to DNA. Reactions involving RNA alone can create copies of short RNA strands, and a new study shows that this replication can occur in a lab setting that mimics a small pore in a volcanically heated rock—a presumably common setting on early Earth. Researchers placed RNA in a small chamber with hot and cold regions and observed molecular movement that helped drive multiple cycles of RNA replication. The number of RNA strands increased by as much as 200,000 times, suggesting that this RNA chemistry may have been a stepping stone to building more complex biomolecules in the prebiotic Earth environment.

In present-day organisms, the two main biochemical functions for life—storing information and driving chemical reactions—are carried out, respectively, by DNA and proteins. However, it seems improbable that both of these complicated types of molecules evolved simultaneously. So biologists have proposed that RNA performed both roles to jumpstart life on Earth [1]. Like DNA, RNA is composed from a set of four nucleotides that can be arranged to form a genetic code. RNA can also assume structural forms that act as catalysts that drive reactions. One problem for origin-of-life theories is that these RNA catalysts, or “ribozymes,” are highly temperature sensitive, raising doubts about their effectiveness in a natural setting, says Dieter Braun from the Ludwig Maximilian University of Munich (LMU).