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  2. Carbon tetrafluoride - Wikipedia

    en.wikipedia.org/wiki/Carbon_tetrafluoride

    Abundances are given as pollution free monthly mean mole fractions in parts-per-trillion. Atmospheric concentration of CF 4 (PFC-14) vs. similar man-made gases (right graph). Note the log scale. Tetrafluoromethane is a potent greenhouse gas that contributes to the greenhouse effect.

  3. Nucleic acid structure - Wikipedia

    en.wikipedia.org/wiki/Nucleic_acid_structure

    Secondary structure is the set of interactions between bases, i.e., which parts of strands are bound to each other. In DNA double helix, the two strands of DNA are held together by hydrogen bonds. The nucleotides on one strand base pairs with the nucleotide on the other strand. The secondary structure is responsible for the shape that the ...

  4. Nucleic acid double helix - Wikipedia

    en.wikipedia.org/wiki/Nucleic_acid_double_helix

    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 ...

  5. Molecular models of DNA - Wikipedia

    en.wikipedia.org/wiki/Molecular_models_of_DNA

    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 ...

  6. DNA - Wikipedia

    en.wikipedia.org/wiki/DNA

    Chemical structure of DNA; hydrogen bonds shown as dotted lines. Each end of the double helix has an exposed 5' phosphate on one strand and an exposed 3′ hydroxyl group (—OH) on the other. DNA is a long polymer made from repeating units called nucleotides.

  7. Structural formula - Wikipedia

    en.wikipedia.org/wiki/Structural_formula

    Skeletal structural formula of Vitamin B 12.Many organic molecules are too complicated to be specified by a molecular formula.. The structural formula of a chemical compound is a graphic representation of the molecular structure (determined by structural chemistry methods), showing how the atoms are connected to one another. [1]

  8. Nucleic acid sequence - Wikipedia

    en.wikipedia.org/wiki/Nucleic_acid_sequence

    For DNA, with its double helix, there are two possible directions for the notated sequence; of these two, the sense strand is used. Because nucleic acids are normally linear (unbranched) polymers, specifying the sequence is equivalent to defining the covalent structure of the entire molecule.

  9. Phosphodiester bond - Wikipedia

    en.wikipedia.org/wiki/Phosphodiester_bond

    Specifically, it is the phosphodiester bonds that link the 3' carbon atom of one sugar molecule and the 5' carbon atom of another (hence the name 3', 5' phosphodiester linkage used with reference to this kind of bond in DNA and RNA chains). [3] The involved saccharide groups are deoxyribose in DNA and ribose in RNA.