Chemical Origins of Life: How did it come about?
Sudha Rajamani, Indian Institute of Science and Education and Research, Pune
The question posed in the talk's title not only happens to be a very fascinating scientific mystery, but also continues to be a fundamental question in Astrobiology. Research being pursued in my lab, and by others in this field, has implications for gaining basic understanding about relevant pathways that might have allowed for the transition of chemistry to biology on prebiotic Earth. In particular, the processes by which polymers capable of information storage and catalysis, emerged and propagated on early Earth, constitutes a crucial chunk of this puzzle. In this context, I will discuss scenarios and mechanisms pertaining to the origin and replication of molecules of an RNA world. The widely accepted RNA world hypothesis posits that RNA performed the dual role of catalysis (ribozymes) and information storage, during a very early stage of life. This theory simplifies the type of biopolymer that had to be present for the origin and early evolution of life on Earth. It does so by reducing the complexity that is encountered in extant biology (three major classes of biopolymers i.e. RNA-DNA-protein); by narrowing it down to one ‘multitasking’ molecule (RNA) very early on, which subsequently got encapsulated within amphiphilc structures (vesicles), resulting in self-replicating chemical entities (protocells). This would have kick-started macromolecular evolution and eventually set the stage for the emergence of cellular life. I will present an overview of these aspects of Astrobiology research which should soon enable answering a vital question in the field: how did life originate and replicate very early on by chemical means?