urasil

Urasil is the Turkish name for uracil, a pyrimidine nucleobase that is one of the four building blocks of RNA. In RNA, uracil pairs with adenine through two hydrogen bonds, helping encode genetic information and participate in transcription and translation. Uracil is not a standard component of DNA, which uses thymine instead.

Chemical identity and properties: uracil has the formula C4H4N2O2 and a molar mass of about 112.09 g/mol. It predominantly exists in the keto tautomer under physiological conditions and is a relatively polar, hydrogen-bond–forming molecule. It is found in RNA as the nucleobase and also exists in free form as a nucleobase or in the form of uridine when glycosidically linked to ribose.

Biological role and metabolism: uracil is synthesized in cells through the pyrimidine biosynthetic pathway and can be used to form uridine monophosphate (UMP), which is further converted to other RNA precursors (UTP, CTP). It is incorporated into RNA during transcription and is one of the standard bases in all cellular RNA. In DNA, uracil is typically absent; cytosine can deaminate to uracil, and the presence of uracil in DNA triggers repair pathways, such as base excision repair mediated by uracil-DNA glycosylase.

laboratory and practical uses: in molecular biology, dUTP and dTTP are used in PCR and sequencing workflows; methods using uracil-DNA glycosylase (UNG) exploit uracil in DNA to prevent carryover contamination, because UNG removes uracil-containing DNA templates before amplification.

See also: uracil, RNA, thymine, nucleotide, base pairing.