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'''Deoxyribonucleic acid''' (DNA) is an [[organic compound|organic]] [[chemical compound]] made up of [[molecule]]s shaped like a [[double helix]], a continuously twisted ladder. The individual monomeric building blocks of DNA (and other nucleic acids) are [[nucleotides]], which themselves consist of three principle moieties: A nitrogenous base, a sugar, and a phosphate group.   

'''Deoxyribonucleic acid''' (DNA) is an [[organic compound|organic]] [[chemical compound]] made up of [[molecule]]s shaped like a [[double helix]], a continuously twisted ladder. The individual monomeric building blocks of DNA (and other nucleic acids) are [[nucleotide]]s, which themselves consist of three principle moieties: A nitrogenous base, a sugar, and a phosphate group.   

DNA carries the [[gene|genet]]ic coding for the [[protein]]s that form the bodies of living [[organism]]s. All organisms contain DNA, and the DNA of a sexually reproducing organism is a mix of its parents' DNA.

DNA carries the [[gene|genet]]ic coding for the [[protein]]s that form the bodies of living [[organism]]s. All organisms contain DNA, and the DNA of a sexually reproducing organism is a mix of its parents' DNA.

==History==

==History==

In the late 19th century [[Friedrich Miescher]], a Swiss [[biochemist]], discovered several different proteins and an unusual [[acid]] in the [[nucleus]] of cells. The acid was named deoxyribonucleic acid, or DNA. In 1944 two American [[biologist]]s, [[Alfred Hershey]] and [[Martha Chase]] used experiments with [[bacteria]] and [[bacteriophages]] to show that DNA passed [[gene]]s from one generation to the next.  

In the late 19th century [[Friedrich Miescher]], a Swiss [[biochemist]], discovered several different proteins and an unusual [[acid]] in the [[nucleus]] of cells. The acid was named deoxyribonucleic acid, or DNA. In 1944 two American [[biologist]]s, [[Alfred Hershey]] and [[Martha Chase]] used experiments with [[bacteria]] and [[bacteriophage]]s to show that DNA passed [[gene]]s from one generation to the next.  

At that time, it was unclear how this simple molecule could hold all the complex information controlling the development of humans, animals and plants. Scientists knew it was made of four chemical bases called [[adenine]] (A), [[thymine]] (T), [[guanine]] (G) and [[cytosine]] (C), plus [[phosphoric acid]] and a [[sugar]]. They also knew that there was always the same amount of A as T and of G as C in cells, but they did not know the rules that controlled the arrangement.

At that time, it was unclear how this simple molecule could hold all the complex information controlling the development of humans, animals and plants. Scientists knew it was made of four chemical bases called [[adenine]] (A), [[thymine]] (T), [[guanine]] (G) and [[cytosine]] (C), plus [[phosphoric acid]] and a [[sugar]]. They also knew that there was always the same amount of A as T and of G as C in cells, but they did not know the rules that controlled the arrangement.