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The double-helix model of DNA structure was first published in the journal Nature by James Watson and Francis Crick in 1953, [6] (X,Y,Z coordinates in 1954 [7]) based on the work of Rosalind Franklin and her student Raymond Gosling, who took the crucial X-ray diffraction image of DNA labeled as "Photo 51", [8] [9] and Maurice Wilkins, Alexander Stokes, and Herbert Wilson, [10] and base-pairing ...
Watson and Crick's calculations from Gosling and Franklin's photography gave crucial parameters for the size and structure of the helix. [ 16 ] Photo 51 became a crucial data source [ 17 ] that led to the development of the DNA model and confirmed the prior postulated double helical structure of DNA, which were presented in the series of three ...
As DNA polymerases can only extend a DNA strand in a 5′ to 3′ direction, different mechanisms are used to copy the antiparallel strands of the double helix. [105] In this way, the base on the old strand dictates which base appears on the new strand, and the cell ends up with a perfect copy of its DNA.
A-DNA is thought to be one of three biologically active double helical structures along with B-DNA and Z-DNA. It is a right-handed double helix fairly similar to the more common B-DNA form, but with a shorter, more compact helical structure whose base pairs are not perpendicular to the helix-axis as in B-DNA.
The tertiary arrangement of DNA's double helix in space includes B-DNA, A-DNA, and Z-DNA. Triple-stranded DNA structures have been demonstrated in repetitive polypurine:polypyrimidine Microsatellite sequences and Satellite DNA. B-DNA is the most common form of DNA in vivo and is a more narrow, elongated helix than A-DNA. Its wide major groove ...
The chemical structure of DNA is insufficient to understand the complexity of the 3D structures of DNA. In contrast, animated molecular models allow one to visually explore the three-dimensional (3D) structure of DNA. The DNA model shown (far right) is a space-filling, or CPK, model of the DNA double helix. Animated molecular models, such as ...
DNA is a double-helix molecule, and its distinctive shape is often described as a twisted ladder. The outside of the twisted ladder is composed of sugar and phosphate groups, while the rungs, or steps, of the ladder are formed by two nucleobases connecting to each other via hydrogen bonds .
The double helix is an important tertiary structure in nucleic acid molecules which is intimately connected with the molecule's secondary structure. A double helix is formed by regions of many consecutive base pairs. The nucleic acid double helix is a spiral polymer, usually right-handed, containing two nucleotide strands which base pair together.