purine

(noun)

any of a class of organic heterocyclic base containing fused pyrimidine and imidazole rings; they are components of nucleic acids

Related Terms

Examples of purine in the following topics:

  • DNA Repair

    • Transition substitution refers to a purine or pyrimidine being replaced by a base of the same kind; for example, a purine such as adenine may be replaced by the purine guanine.
    • Transversion substitution refers to a purine being replaced by a pyrimidine or vice versa; for example, cytosine, a pyrimidine, is replaced by adenine, a purine.

  • DNA and RNA

    • Adenine and guanine are classified as purines.
    • The primary structure of a purine consists of two carbon-nitrogen rings.
    • Bases can be divided into two categories: purines and pyrimidines.
    • Purines have a double ring structure, and pyrimidines have a single ring.

  • The Structure and Sequence of DNA

    • The nitrogenous base can be a purine such as adenine (A) and guanine (G), characterized by double-ring structures, or a pyrimidine such as cytosine (C) and thymine (T), characterized by single-ring structures.
    • Only the pairing between a purine and pyrimidine can explain the uniform diameter.
    • That is to say, at each point along the DNA molecule, the two sugar phosphate backbones are always separated by three rings, two from a purine and one from a pyrimidine.
    • Base pairing takes place between a purine and pyrimidine stabilized by hydrogen bonds: A pairs with T via two hydrogen bonds and G pairs with C via three hydrogen bonds.

  • Nitrogenous Waste in Birds and Reptiles: Uric Acid

    • Uric acid is a compound similar to purines found in nucleic acids.
    • The enzyme xanthine oxidase makes uric acid from xanthine and hypoxanthine, which in turn are produced from other purines.

  • The DNA Double Helix

    • For example, a certain purine can only pair with a certain pyrimidine.

  • Types of RNA

    • Bases can be divided into two categories: purines and pyrimidines.
    • Purines have a double ring structure, and pyrimidines have a single ring.