An organic substance occurring in chromosomes in the nuclei of cells, which encodes and carries genetic information, and is the fundamental element of heredity.

As the transmitter of inherited characteristics, deoxyribonucleic acid (DNA) replicates itself exactly and determines the structure of new organisms, which it does by governing the structure of their proteins. The Swiss researcher Friedrich Miescher first discovered DNA in 1869 when he extracted a substance (which he called nuclein) containing nitrogen and phosphorus from cell nuclei. The question of whether nucleic acids or proteins, or both, carried the information that make the genes of every organism unique was not answered, however, until the molecular structure of DNA was determined in 1953. This pioneering work was accomplished by an American biochemist, James D. Watson, and two British scientists, Francis Crick, a biochemist, and Maurice...