What is the correct pairing of nitrogen bases in DNA?

In DNA, the correct pairing of nitrogen bases is characterized by specific interactions that facilitate the formation of the double helix structure. Adenine pairs exclusively with thymine, establishing two hydrogen bonds between them, which helps maintain the stability of DNA. Meanwhile, cytosine pairs with guanine, forming three hydrogen bonds, which also contributes to the overall strength and integrity of the DNA molecule.

This complementary base pairing is essential for accurate DNA replication and transcription processes, where the sequence of bases encodes genetic information. The pairing ensures that when DNA strands separate, each strand can serve as a template for creating a new complementary strand, preserving genetic fidelity across cell divisions and generations.

Other pairings do not accurately reflect the established base pairing rules found in DNA. For instance, adenine does not pair with guanine, nor does cytosine pair with thymine. Furthermore, uracil is found in RNA instead of DNA, where it replaces thymine. Therefore, the correct and established pairs are adenine with thymine and cytosine with guanine.