* Adenine (A) pairs with Thymine (T)

* Guanine (G) pairs with Cytosine (C)

This pairing is based on the structure of the bases and their ability to form hydrogen bonds with each other.

* Adenine and thymine form two hydrogen bonds between them.

* Guanine and cytosine form three hydrogen bonds between them.

These specific pairings are crucial for DNA's structure and function:

* Replication: During DNA replication, the two strands of the DNA molecule separate, and each strand serves as a template for the synthesis of a new complementary strand. The base pairing rules ensure that the new strands are identical to the original strands.

* Transcription: During transcription, one strand of DNA is used as a template to synthesize a molecule of RNA. The base pairing rules ensure that the RNA molecule is a faithful copy of the DNA sequence.

* Genetic code: The order of the bases in DNA determines the sequence of amino acids in proteins. This sequence is read in groups of three bases called codons. The base pairing rules ensure that the correct amino acids are incorporated into proteins.

In summary, the complementary base patterns in DNA are essential for maintaining the integrity of the genetic code and for carrying out essential biological processes.