Image by Richard Wheeler, used with permission
Z-DNA is a little thinner, and the backbone of each strand of the double helix (in red and orange above, and in hematite below) isn't a smooth, ribbon-like path. Rather, Z-DNA has a jagged backbone that zigzags with each pair of bases up and down the double helix. Its major and minor grooves are also less pronounced than in B-DNA. Z-DNA forms rarely in biology, and is generally found in DNA with a specific sequence; in this case, alternating pyrimidine-purine sequences, such as CGCGCGCGCG.
With some tinkering, I was able to create a Z-DNA version of my beaded PI-MtuI sequence. The original B-DNA version is on the right, and the new Z-DNA version is on the left:
my own variations on Gwen's pattern, but when it came time to peyote stitch up and down the backbones of each strand (at about the 7 minute mark in the pattern), I added two 11° seed beads where I would have added one 8° seed bead. Then I zipped up and down the backbones once more, adding a 15° seed bead at the same place as the 11° seed beads, alternating its placement on either side of the 11° beads so that the backbones zig zag:
DNA replication, and the very cool Holliday junctions created during meiosis and in some kinds of DNA repair. However, those structures will have to be topics for another blog post.