DoppelstrangDNA

DoppelstrangDNA, widely referred to as double-stranded DNA, is the molecule that stores most genetic information in organisms. It consists of two long polynucleotide strands wound into a right-handed double helix. The strands are antiparallel; one runs 5' to 3' and the other 3' to 5'. The sugar-phosphate backbone forms the outer frame, while adenine pairs with thymine and guanine pairs with cytosine, producing complementary base pairs and a stable structure. The helix contains major and minor grooves, which are important for protein interactions.

In replication, the two strands separate at the replication fork and serve as templates for new strands in a semi-conservative process. DNA polymerases synthesize the new strands; the leading strand is built continuously, while the lagging strand is formed as Okazaki fragments that are later joined. Primers initiate synthesis, and proofreading enzymes help ensure fidelity. DNA repair mechanisms fix damaged bases, cross-links, and mismatches to preserve genome integrity.

The canonical form is B-DNA, though A-DNA and Z-DNA can arise under different conditions or sequences. In eukaryotes, dsDNA is packaged with histone proteins into chromatin, with nucleosomes folding into higher-level structures that regulate gene accessibility. Many prokaryotes carry dsDNA that is typically circular and associated with DNA-binding proteins rather than histones. Topoisomerases control supercoiling during replication and transcription.

DoppelstrangDNA functions as the carrier of genetic information, guiding development, physiology, and evolution. Its sequence encodes genes and regulatory elements; transcription produces RNA, which is translated into proteins or performs other roles. Damage, mutation, and recombination generate genetic variation, while repair and proofreading maintain stability. Modern biology relies on dsDNA awareness in techniques such as PCR, sequencing, and genome editing.