So we have the five end here and the three end here for the first chain and the three end here and the five end here for that second chain. And so in this particular case, let's imagine that the axis of rotation basically lies along our Y axis and these two strands essentially curl around, they coil around our common axis. This is point number one. So a single DNA molecule consists of two individual nucleic acid chains that wind about a common axis and these two polynucleotide chains run in opposite directions. So although they are parallel, they run in opposite directions. B, the backbone of.