The molecule of heredity
Double helix of deoxyribonucleotides
DNA (deoxyribonucleic acid) is a double-stranded helix built from four nucleotide bases — adenine (A), thymine (T), guanine (G), and cytosine (C). The two strands are held together by hydrogen bonds between complementary base pairs (A–T and G–C), and their sequence encodes all genetic information. In eukaryotes, DNA is tightly coiled around histone proteins and packaged into chromosomes inside the nucleus.