Figure 1.

Types of self-replication. Type 1 is the self-replication reaction in which the information molecule (DNA or RNA) is replicated by an exogenous enzyme and includes PCR, 3SR and RNA replication by Qβ replicase. Type 2 self-replication does not require any replication enzymes and these reactions include self-ligating ribozymes, self-replicating peptides. Type 3 is a modification of type 1 in which the replication enzyme is supplied internally by synthesis rather than being exogenously added.