dobbelstrengede

Dobbelstrengede, in a biological context, describes molecules composed of two polynucleotide chains that are complementary and run in opposite directions. The most well-known example is double-stranded DNA, which forms the classic double helix. The two strands are antiparallel and held together mainly by hydrogen bonds between base pairs: adenine pairs with thymine (A–T) and guanine pairs with cytosine (G–C) in DNA, while RNA uses uracil in place of thymine.

The backbone of each strand is a sugar-phosphate chain, with the bases stacked inside the helix. The double-stranded arrangement provides stability and serves as a template for replication and transcription. In organisms, the genome is typically organized as double-stranded DNA, with replication producing two daughter duplexes that preserve genetic information. Transcription uses one DNA strand as a template to synthesize RNA.

Double-stranded structures also occur in other contexts, such as double-stranded RNA (dsRNA), which is found in certain viruses and in regulatory RNA molecules. In cells, RNA can form double-stranded regions through folding or base-pairing with other RNA strands.

In laboratory settings, double-stranded DNA can be denatured by heat to separate the strands and then re-annealed by cooling. The stability of a double-stranded molecule depends on factors including length, base composition, and GC content, which influences melting temperature and structural integrity.