Fig. 2From: Trinity of G-tetrads and origin of translationEmergence of the quadruplex domain (QD) in the quadruplex world. A G-tetrad with cation in the center. B Steps in prebiotic polymerization of quadruplexes from free guanines (G) stacked into G-tetrads. Only G-tetrads (gray disks) and phosphodiester backbone (arrows) are shown. Curved lines in QDs correspond to Z-shaped G-loopsBack to article page