Hurry explain how the dna molecule is stabilized but also able to be changed.

The nitrogenous bases placed in between the DNA double helix strands, like rungs on a ladder, are positioned there because of the hydrophobic effect and are stabilized by hydrogen bonding. The stability of DNA also relies on the interactions between the hydrogen bonds between bases, hydrogen bonds between bases and surrounding water, and base interaction between neighboring bases.

Hydrogen bonds are able to stabilize the DNA double helix by pairing up with their complementary base pairs (guanine with cytosine and adenine with thymine)

Hope this was able to help you! I went through my answer and bolded the more important parts, and parts more useful for answering the question.

Gravitational force i believe