That is, the two single stranded DNA, this one and this one run in the parallel direction, but they run in the opposite direction, meaning that this goes from the five to the three carbon and this runs from the three to the five carbon. So once again, we have our notice that if the first strand runs in the five three direction, then the complementary strand must run in the reverse three to five direction. And this type of arrangement is known as antiparallel. And the reason the two DNA molecules run antiparallel is to ensure that the bonding between our nitrogenous bases is exactly right, so that we create strong bonds between our two DNA molecules and so that our double stranded DNA molecule basically doesn't unzip itself spontaneously. So this is a slightly better description of our DNA molecule because this shows our double helix structure. So we have the blue and our purple strand.