Emäsparisääntö

Emäsparisääntö, also known as base pairing rule, is a fundamental principle in molecular biology that describes the specific way nitrogenous bases in nucleic acids (DNA and RNA) pair with each other. In DNA, adenine (A) always pairs with thymine (T) through two hydrogen bonds, while guanine (G) always pairs with cytosine (C) through three hydrogen bonds. This complementary pairing is essential for maintaining the structure of the DNA double helix and for accurately replicating genetic information.

The same pairing rules apply in RNA, with a key difference: uracil (U) replaces thymine (T). Therefore, in RNA, adenine (A) pairs with uracil (U), and guanine (G) still pairs with cytosine (C). This base pairing is crucial for processes like transcription, where a DNA sequence is copied into an RNA molecule, and translation, where the RNA sequence is used to synthesize proteins. The specificity of these pairings ensures that genetic information is transferred faithfully from DNA to RNA and then to protein, underlying the central dogma of molecular biology. The emäsparisääntö is a cornerstone for understanding genetics, heredity, and the molecular mechanisms of life.