The Edge of Life

Irene Chen
FAS Center for Systems Biology, Harvard University

During the origin of life, replicating cells arose from replicating molecules and replicating molecular assemblies. How might the two components of a protocell, a membrane and a genome, combine to produce a unified cellular 'system'? For example, we showed that growth of fatty acid vesicles generates a transmembrane pH gradient, which could be useful for cellular processes, such as genomic replication. We also observed the emergence of competition between vesicles encapsulating RNA and empty vesicles. During cellular evolution, vesicles encapsulating highly active genomic replicators would grow at the expense of other vesicles, translating genomic fitness into cellular fitness. This would be a first step toward the emergence of natural selection among cells. These results highlight the prospect of building a protocell with apparently complex behaviors using simple components and physico-chemical processes.

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