DNA Structure

Elements | Molecular Structure | Backbone | Base Pairs

The variable part of DNA is its sequence of base pairs. If all of your genetic information can be compared to a how-to manual, than the DNA sequence is the alphabet with which it is written.

Because of the structures of the bases, adenine is complimentary to thymine, forming two hydrogen bonds, and guanine is complimentary to cytosine, forming three hydrogen bonds. In other words, guanine only binds to cytosine and adenine only binds to thymine.