Final answer:
The two asymmetrical grooves on the outside of a DNA double helix are known as the major groove and the minor groove. The major groove is wider and more accessible to proteins, making it a preferred site for protein-DNA interactions. The minor groove, on the other hand, is narrower and less accessible.
Step-by-step explanation:
The two asymmetrical grooves on the outside of a DNA double helix are known as the major groove and the minor groove. These grooves are formed by the asymmetrical spacing of the sugar-phosphate backbones in DNA. The major groove is wider and more accessible to proteins, making it a preferred site for protein-DNA interactions. Conversely, the minor groove is narrower and less accessible.