Double-stranded DNA

Double-stranded DNA is the molecule that carries genetic information in living organisms. It’s composed of two long strands coiled into a spiral, resembling a twisted ladder or double helix. Each strand is made of nucleotide units, which consist of a sugar, a phosphate group, and a base. The bases pair specifically—adenine with thymine, and cytosine with guanine—holding the two strands together through hydrogen bonds. This structure allows DNA to store, replicate, and transmit genetic instructions essential for life processes.