DNSmolekulára

DNSmolekulára is the molecule that carries the genetic information essential for the growth, development, and functioning of most living organisms and many viruses. It is a polymer composed of nucleotides, and its sequence encodes hereditary instructions.

DNSmolekulára consists of two long polynucleotide chains that form a double helix. Each nucleotide contains a deoxyribose sugar, a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine). Bases pair specifically (A–T, C–G) through hydrogen bonds, creating the rungs of the ladder, while the sugar-phosphate backbones form the sides. The strands run antiparallel. In the common B-form, the molecule is about 2 nanometers in diameter, with roughly 3.4 Å per base pair and about 10.5 base pairs per turn.

DNSmolekulára is packaged inside cells as chromatin in eukaryotes, where DNA winds around histones to form nucleosomes and higher-order structures. In prokaryotes, DNA is typically a closed circular chromosome. Genome size varies from a few thousand to billions of base pairs.

Functionally, DNSmolekulára stores the information needed to build and regulate an organism. Genes specify RNA and protein products, while regulatory elements control expression. DNA replicates semiconservatively during cell division: helicase unwinds the double helix, DNA polymerases synthesize new strands, and ligases seal fragments. The information flow follows the central dogma: DNA transcribes to RNA, which translates into proteins.

Historical note: The double-helix model was proposed in 1953 by Watson and Crick, aided by Chargaff’s rules and Rosalind Franklin’s data. Advances in sequencing and molecular genetics have enabled modern genomics, diagnostics, and biotechnology.