Which nitrogenous bases in DNA are classified as purines?

Purines are characterized by their two-ring structure and are one of the two categories of nitrogenous bases found in nucleic acids. In DNA, the purines include adenine and guanine. Both of these bases play essential roles in the genetic coding and structural components of DNA, forming complementary pairs with pyrimidines (thymine and cytosine) during the formation of the double helix structure. Understanding that purines consist of adenine and guanine is fundamental for grasping the molecular structure of DNA, as well as its replication and transcription processes.