<prompt> The Z DNA helixHas fewer base pairs per turn than B DNAIs ored by an alternating GC sequencesTends to be found at 3 end to genesIs inhibited by methylation of the bases  <response>: Z-DNA is one of the many possible double helical structures of DNA. It is a left-handed double helical structure in which the double helix winds to the left in a zig-zag pattern instead of to the right, like the more common B-DNA form. Z-DNA is thought to be one of three biologically active double helical structures along with A- and B-DNA. 