What type of bond connects the bases in the double helix structure of DNA?

The bases in the double helix structure of DNA are connected by hydrogen bonds. Each base pair consists of complementary bases – adenine pairs with thymine, and cytosine pairs with guanine. The hydrogen bonds between these bases provide the necessary stability to the DNA structure while still allowing the strands to separate during processes like replication and transcription.

Covalent bonds, on the other hand, are found in the backbone of the DNA molecule, linking the sugar and phosphate groups, but they do not connect the nitrogenous bases themselves. Ionic bonds involve the transfer of electrons and would not be appropriate for the pairing of bases, while peptide bonds are specific to proteins and connect amino acids together. Therefore, hydrogen bonds are essential for maintaining the structure of DNA by linking the base pairs.