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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 ...
Henrietta Lacks (born Loretta Pleasant; August 1, 1920 – October 4, 1951) [2] was an African-American woman [5] whose cancer cells are the source of the HeLa cell line, the first immortalized human cell line [B] and one of the most important cell lines in medical research. An immortalized cell line reproduces indefinitely under specific ...
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 makes it more accessible to proteins. On the other hand, it has a narrow minor groove. B-DNA's favored conformations occur at high water concentrations; the hydration of the minor groove appears to favor B-DNA.
The two strands of DNA in a double helix can thus be pulled apart like a zipper, either by a mechanical force or high temperature. [27] As a result of this base pair complementarity, all the information in the double-stranded sequence of a DNA helix is duplicated on each strand, which is vital in DNA replication.
For biological systems with water as a solvent, hydrophobic effect contributes and helps in formation of a helix. [8] Stacking is the main stabilizing factor in the DNA double helix. [9] Contribution of stacking to the free energy of the molecule can be experimentally estimated by observing the bent-stacked equilibrium in nicked 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, the third strand binds to a B-form DNA (via Watson–Crick base-pairing ) double helix by forming Hoogsteen base pairs or reversed Hoogsteen hydrogen bonds.
Like the more common B-DNA, A-DNA is a right-handed double helix with major and minor grooves. However, as shown in the comparison table below, there is a slight increase in the number of base pairs (bp) per turn. This results in a smaller twist angle, and smaller rise per base pair, so that A-DNA is 20-25% shorter than B-DNA.
Semiconservative replication describes the mechanism of DNA replication in all known cells. DNA replication occurs on multiple origins of replication along the DNA template strands. As the DNA double helix is unwound by helicase, replication occurs separately on each template strand in antiparallel directions. This process is known as semi ...