And that means these two bands here have the same exact heaviness have the same exact density while this band, the second band, is found farther to the left along the x axis and so it is slightly lighter. Now, what exactly does that actually describe? Well, once again, it confirms the semiconservative replication process. What that means is each one of these strands here separated. Now, when the N 15 strand is separated, the purple one, we use the N 14 isotopes. And so we basically form this molecule right over here.