And because this distance of 3.4 angstroms is the perfect distance for London dispersion forces, that means we also have these Vandervile forces holding our bases together and contributing to the overall structure of the DNA molecule. And finally, we also have the hydrophobic effect and the hydrophobic interaction. So remember, inside the nucleus of ourselves, we have an aqueous environment that consists of the water molecule. And because water is polar, what that means is this DNA molecule exists in a polar environment. And that's exactly why the backbone, which contains the polar phosphate groups, essentially lie on the outside, and these relatively non polar bases essentially cluster on the inside. And because of this hydrophobic effect, these bases are able to cluster very well on the inside and they create the stacking effect and that leads to these Vandervile forces and these hydrogen bonds.