Fig. 5. Loop closure entropy in various ensemble diagrams. (a) A diagram with three folded segments, , connects to close a partially folded segment, , into a loop. The entropy cost is estimated as a fraction of the entropy cost to close a fully unfolded loop with effective length l. Similar estimates are used to describe nested (b) and coupled (c) loops in SI Text.

Fig. 6. Fraction of diagrams with n unfolded loops, P_n(q), near the melting point. P₄(q) is the fraction of diagrams in SI Fig. 5c.

Fig. 7. Comparison of the free energy profile neglecting loops (black), and neglecting the extension term r²/la² (indigo) to the model described in the text (blue).