"Stepping Out of the Shadows: The History of the RNA World"
Although as late as 1942 the possibility that bacteria were endowed with genetic material was held in doubt, the molecularization of biology led to the acknowledgement of the key role that RNA molecules play in major biological processes and to discuss the idea that RNA could have preceded DNA as genetic material. It was not until the late 1960s when Rich, Woese, Orgel and Crick suggested independently that RNA molecules could exhibit catalytic activity, as is now well established—but did life start with an RNA World? The discovery of catalytically active RNA molecules has provided considerable credibility to these suggestions that the first living entities were largely based on ribozymes, in an early stage called the RNA world. However, at the time being the hiatus between the primitive soup and the RNA world is discouragingly enormous. Bioinformatics and comparative genomics provide important insights into some very early stages of biological evolution, but it is difficult to see how their applicability can be extended beyond a threshold that corresponds to a period in which protein biosynthesis was already in operation, i.e., the RNA/protein world. The evidence suggesting that ribonucleotide-derived coenzymes, histidine and other imidazole-bearing compounds can be considered vestiges of such early epochs will be discussed.
About the Speaker
Our work is centered on the origin and early evolution of life. The first issue has been addressed using laboratory simulations of the prebiotic environment and analysis of carbon-rich meteorites, and the second point has been based on the reconstruction of ancestral genomes and early evolution of metabolic pathways, using comparative genomics and bioinformatic tools.
About this Series
Weekly talks given by leading thinkers in the areas of geology, geophysics, geobiology, geochemistry, atmospheric science, oceanography, climatology, and planetary science. Lectures take place on Wednesdays from 3:45pm in MIT Building 54 room 915, unless otherwise noted.