So if we examine the following diagram, these are the backbones and these are the nitrogenous bases. And remember, in our study on the backbone we said that a backbone consists of these repeating units of sugar phosphate groups. So we have sugar phosphate, sugar phosphate, sugar phosphate, and that runs along the entire backbone. And in the diagram these arrows are basically our backbone. Now what they were able to show is that the backbone is found on the outside portion, on the exterior portion of that DNA molecule and that's because these phosphate groups found on a backbone contain negative charges and they are stabilized by the aqueous environment that contains polar water molecules. And we'll examine that in much more detail in the next several electros.