March 21, 1932 (a Monday)

On this date, the American molecular biologist Walter Gilbert was born. In 1980, he was awarded the Nobel Prize in Chemistry with Frederick Sanger and Paul Berg. Gilbert and Sanger were recognized for their pioneering work in devising methods for determining the sequence of nucleotides in a nucleic acid.

A Maxam-Gilbert sequencing gel.

A Maxam-Gilbert sequencing gel.

In a 1986 article (Nature 319: 618), Gilbert was the first scientist to use the term “RNA world” to refer to a possible stage in the origin of life on Earth (although the hypothetical possibility of an RNA world had already been suggested by others before him):

The first stage of [chemical] evolution proceeds, then, by RNA molecules performing the catalytic activities necessary to assemble themselves from a nucleotide soup. The RNA molecules evolve in self-replicating patterns, using recombination and mutation to explore new niches. … they then develop an entire range of enzymic activities. At the next stage, RNA molecules began to synthesize proteins, first by developing RNA adaptor molecules that can bind activated amino acids and then by arranging them according to an RNA template using other RNA molecules such as the RNA core of the ribosome. This process would make the first proteins, which would simply be better enzymes than their RNA counterparts. … These protein enzymes are … built up of mini-elements of structure.

Finally, DNA appeared on the scene, the ultimate holder of information copied from the genetic RNA molecules by reverse transcription. … RNA is then relegated to the intermediate role it has today—no longer the center of the stage, displaced by DNA and the more effective protein enzymes.

The possibility of an RNA world in the origin of life had been supported by the discovery by Thomas Cech in 1982 of the existence of naturally-occurring ribozymes.

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