Guanine

Definition

Guanine is one of the four main nucleobases found in DNA and RNA, represented by the letter G. It pairs with cytosine (C) through three hydrogen bonds in the DNA double helix.

5 Must Know Facts For Your Next Test

1. Guanine is a purine base, characterized by its double-ring structure composed of carbon and nitrogen atoms.
2. In DNA, guanine always pairs with cytosine via three hydrogen bonds, contributing to the stability of the DNA molecule.
3. Guanine can be methylated to form 7-methylguanine, which is involved in regulatory functions like gene expression.
4. Oxidative damage to guanine can result in mutations; for example, 8-oxoguanine is a common oxidation product that can cause GC to TA transversions in DNA.
5. Guanine's role extends to RNA as well, where it participates in various structural and catalytic functions.

Review Questions

• What type of bond does guanine form with cytosine in the DNA double helix?
• How does oxidative damage to guanine affect genetic stability?
• What distinguishes guanine structurally from other nucleobases?

Related terms

Adenine:

Adenine is a purine nucleobase that pairs with thymine in DNA and uracil in RNA.

Cytosine:

Cytosine is a pyrimidine nucleobase that pairs with guanine in both DNA and RNA.

Purines: Purines are a group of nucleobases, including adenine and guanine, characterized by their double-ring structure.