Final answer:
The complementary base pair rule states that adenine pairs with thymine or uracil, and cytosine pairs with guanine in DNA.
Step-by-step explanation:
The complementary base pair rule is a fundamental principle governing the structure of DNA and RNA.
In DNA, adenine (A) consistently pairs with thymine (T), forming two hydrogen bonds, while cytosine (C) consistently pairs with guanine (G), forming three hydrogen bonds.
This specificity ensures the fidelity of genetic information transfer during processes like DNA replication and transcription.
The hydrogen bonds between complementary base pairs contribute to the stability of the DNA double helix.
This rule not only underlies the structure of the genetic code but also plays a crucial role in various cellular processes, highlighting the precision and reliability of molecular interactions fundamental to life's genetic machinery.