So to see what we mean, let's take a look at the following picture. So, in diagram one, we basically have our two single stranded DNAs. So DNA one and DNA two and we form this double helix structure. Now, when our helicase or helicase actually binds to the origin of replication, it unwinds that double stranded DNA. And once our two single stranded DNAs are exposed and once we unwind it, we have the single stranded binding proteins bind to each of these two single strands and that keeps those two strands apart. Now, as hellicase unwinds our double helix, that unwinding process actually introduces positive super coils.