Cross-catalysis, complementary

Self-replication can occur through autocatalysis with a self-complementary template (Fig. 2A) or by cross-catalysis with a complementary template (Fig. 2B). In the latter case, two complementary units catalyze each other s formation. This is significant as modern DNA is made up of two complementary strands that replicate in a cross-catalytic manner. Studies on a simple nonenzyinatic DNA system capable of competing auto- and crosscatalysis. show that in the absence of an initial template, both pathways are equally as likely, but that in the presence of a seeding template, the cross-catalytic route is more efficient. 

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