Events occurring in the model and their associated probabilities. Solid arrows represent chemical events and dashed arrows represent other events. ( A ) Events occurring in a grid room. Legends: Npp, nucleotide precursor’s precursor; Np, nucleotide precursor; Nt, nucleotide (A, U, C, or G); Ap, amphiphile precursor; Am, amphiphile; the notations of ribozymes are the same as in the text. Note that for the template-directed synthesis, the probability of a circular RNA turning into a template would be P
instead of P
and the synthesis may start at a random site, whereas other associated events are the same as those for the linear RNA (shown in the figure). Some factors associated with the events are explained in the text. One of these factors, F
, is important for the topic of the present study. For a particular intermediate site between two genes in a linear RNA (see the legend to Figure 2 for details of the assumption concerning the site), the probability of phosphodiester bond breaking (P
) is increased by multiplying the factor, F
, which represents the consideration of the self-cleaving effect. ( B ) Events concerning the behaviors of the protocells. 9 grid rooms are shown in each panel.