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  2. Hydrogen bond - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_bond

    A symmetric hydrogen bond is a special type of hydrogen bond in which the proton is spaced exactly halfway between two identical atoms. The strength of the bond to each of those atoms is equal. It is an example of a three-center four-electron bond. This type of bond is much stronger than a "normal" hydrogen bond.

  3. Nucleic acid structure - Wikipedia

    en.wikipedia.org/wiki/Nucleic_acid_structure

    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 nucleic acid assumes. The bases in the DNA are classified as purines and pyrimidines. The purines are adenine and guanine ...

  4. Alpha helix - Wikipedia

    en.wikipedia.org/wiki/Alpha_helix

    An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix). The alpha helix is the most common structural arrangement in the secondary structure of proteins. It is also the most extreme type of local structure, and it is the local structure that is most easily predicted from a sequence of amino ...

  5. Base pair - Wikipedia

    en.wikipedia.org/wiki/Base_pair

    Base pair. A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA. Dictated by specific hydrogen bonding patterns, "Watson–Crick" (or "Watson ...

  6. Nucleotide base - Wikipedia

    en.wikipedia.org/wiki/Nucleotide_base

    Five nucleobases— adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U)—are called primary or canonical. They function as the fundamental units of the genetic code, with the bases A, G, C, and T being found in DNA while A, G, C, and U are found in RNA. Thymine and uracil are distinguished by merely the presence or absence of a ...

  7. Histone octamer - Wikipedia

    en.wikipedia.org/wiki/Histone_octamer

    This “wave” of DNA, spontaneously breaking and remaking the hydrogen bonds as it goes, then propagates down the nucleosomal DNA until it reaches the last binding site with the histone octamer. Once the wave reaches the end of the histone octamer the excess that was once at the edge is extended into the region of linker DNA.

  8. Protein secondary structure - Wikipedia

    en.wikipedia.org/wiki/Protein_secondary_structure

    Secondary structure is defined by hydrogen bonding, so the exact definition of a hydrogen bond is critical. The standard hydrogen-bond definition for secondary structure is that of DSSP, which is a purely electrostatic model. It assigns charges of ±q 1 ≈ 0.42e to the carbonyl carbon and oxygen, respectively, and charges of ±q 2 ≈ 0.20e to ...

  9. Molecular Structure of Nucleic Acids: A Structure for ...

    en.wikipedia.org/wiki/Molecular_Structure_of...

    t. e. " Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid " was the first article published to describe the discovery of the double helix structure of DNA, using X-ray diffraction and the mathematics of a helix transform. It was published by Francis Crick and James D. Watson in the scientific journal Nature on pages ...