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a purine base, one of the fundamental components of nucleic acids (DNA and RNA).
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

guan·ine (Gua, G),

(gwahn'ēn, -in),
2-Amino-6-oxypurine; one of the two major purines (the other being adenine) occurring in all nucleic acids.
Farlex Partner Medical Dictionary © Farlex 2012


n. Abbr. G
A purine base, C5H5ON5, that is an essential constituent of both RNA and DNA.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


(G) (gwah'nēn)
One of the two major purines (the other being adenine) occurring in all nucleic acids.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


One of the two purine bases of double-ring structure (the other being ADENINE) which, with the PYRIMIDINE bases form the ‘rungs of the ladder’, and the genetic code, in the double helix deoxyribonucleic acid (DNA) molecule. Guanine is also one of the ribonucleic acid (RNA) bases.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
Guanineclick for a larger image
Fig. 183 Guanine . Molecular structure.

guanine (G)

one of four types of nitrogenous bases found in DNA, having the double-ring structure of a class known as PURINES. Guanine forms part of a DNA unit called a NUCLEOTIDE and always forms complementary pairs with a DNA pyrimidine base called CYTOSINE. Guanine also occurs in RNA molecules.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Mizuno et al., "Eukaryotic DNA polymerases a, and e incorporate guanine opposite 2,2,4-triamino-5(2H)-oxazolone," ChemBioChem, vol.
McKenna, "Human DDX21 binds and unwinds RNA guanine quadruplexes," Nucleic Acids Research, vol.
Caption: FIGURE 6: Different arrangements of the guanine bases in the helical structures of 5'-GMP self-assembly formed under acidic (pH 5) and neutral (pH 8) conditions.
Mittermaier, "G-register exchange dynamics in guanine quadruplexes," Nucleic Acids Research, vol.
He determined the quantity of each present and by 1948 was able to demonstrate than, in nucleic acids generally, the number of guanine units was equal to the number of cytosine units, and the number of adenine units was equal to the number of thymine units.
Even with their initial, medium-resolution map, Sancar and colleagues were able to show that repairs of BPDE damage tend to occur more often when the BPDE-burdened guanine (G) is next to a cytosine (C) rather than a thymine (T) or adenine (A).
The most frequently observed position of nucleotide substitutions within HVRI was nucleotide transversion from cytosine (C) to adenine (A) at 16173, a transition of adenine (A) to guanine (G) at 16175, and a transition of cytosine (C) to guanine (G) at 16176 (Fig.
The data actually indicate that the crystals are in the monoclinic [beta]-polymorph of guanine, consistent with the prior findings for the biogenic guanine crystals in all organisms thus far characterized (Hirsch et al.
These include thymine, cytosine, guanine and adenine which are four nucleotides found on life on Earth.
First, they need to identify which ingredients reacted to create RNA's four nucleotides -- adenine, guanine, cytosine, and uracil (A, G, C, and U).
(Last month, three pioneers of cryo-electron microscopy won the 2017 Nobel Prize in Chemistry.) Researchers have long known that the mirror in a scallop eye is made from a molecule called guanine. It's best known as one of the main ingredients of DNA, but in some animals guanine is packed into crystals that reflect light.

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