History of genetics code for specific proteins, leading to the "one gene, one enzyme" hypothesis. Oswald Avery, Colin Munro MacLeod, and Maclyn McCarty showed in 1944 that DNA holds the gene's information. In 1952, Rosalind Franklin and Raymond Gosling produced a strikingly clear x-ray diffraction pattern indicating a helical form, and in 1953, James D. Watson and Francis Crick demonstrated the molecular structure of DNA. Together, these discoveries established the central dogma of molecular biology, which states that proteins are translated from RNA which is transcribed by DNA. This dogma has since been shown to have exceptions, such as reverse transcription in retroviruses.
Triple-stranded DNA Triple-stranded DNA Triple-stranded DNA (also known as H-DNA or Triplex-DNA) is a DNA structure in which three oligonucleotides wind around each other and form a triple helix. In triple stranded-DNA, one strand binds to a B-form DNA (Watson–Crick base-pairing) through Hoogsteen base pair or reversed Hoogsteen hydrogen bonds. A thymine (T) nucleobase can bind to a Watson–Crick base-pairing of T-A by a Hoogsteen hydrogen bond. The thymine attaches to the adosine (A) of the origin double stranded DNA to create a T-A*T base-triplet. In acidic conditions, a protonated cytosine, represented as C+, can form a base-triplet with a C-G pair