Nucleic acids are complex molecules that contain a cell's genetic information and the instructions for carrying out cellular processes. The two nucleic acids, ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), work together.

A molecule is made of phosphate-base-sugar nucleotide chains; its three-dimensional shape affects its genetic function. In humans and other higher organisms, DNA is shaped in a two-stranded helix (spiral) and further organized on structures called chromosomes. DNA in some bacteria is circular. Most RNA molecules are single-stranded and take various shapes, such as a cloverleaf.

Nucleic acids were discovered by the Swiss biochemist Johann Miescher (1844-1895). Born in Basel where his father was a physician, Miescher was an assistant to Ernst Hoppe-Seyler at the University of Strasbourg (then in France, but soon to become part of Germany) in 1859 when he isolated a cellular substance containing nitrogen and phosphorus. Thinking it was a phosphorus-rich nuclear...