Emäspäättelyt

Emäspäättelyt, or base pairing, is a fundamental concept in molecular biology describing the specific way nucleotide bases in nucleic acids, DNA and RNA, associate with each other. This association is driven by hydrogen bonds formed between complementary bases. In DNA, adenine (A) always pairs with thymine (T) via two hydrogen bonds, forming an A-T base pair. Guanine (G) always pairs with cytosine (C) through three hydrogen bonds, forming a G-C base pair. This strict complementarity is crucial for the structure and function of DNA.

In RNA, uracil (U) replaces thymine, so adenine (A) pairs with uracil (U) via two hydrogen bonds (A-U). Guanine (G) still pairs with cytosine (C) through three hydrogen bonds (G-C). These base pairing rules dictate the formation of double-stranded DNA and the transcription of DNA into messenger RNA (mRNA). They are also vital for processes like DNA replication, where each strand serves as a template for synthesizing a new complementary strand, ensuring genetic information is accurately copied.

The stability of a DNA double helix is influenced by the number of G-C pairs, as they have three hydrogen bonds compared to the two in A-T pairs. This specificity of base pairing is the cornerstone of genetic coding, allowing for the storage and transmission of genetic information across generations and the precise synthesis of proteins.