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Uracil (/ ˈ j ʊər ə s ɪ l /) (symbol U or Ura) is one of the four nucleotide bases in the nucleic acid RNA. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine (T). Uracil is a demethylated form of thymine.
Both RNA and DNA contain two major purine bases, adenine (A) and guanine (G), and two major pyrimidines. In both DNA and RNA, one of the pyrimidines is cytosine (C). However, DNA and RNA differ in the second major pyrimidine. DNA contains thymine (T) while RNA contains uracil (U).
Regarding the natural history, uracil came first then thymine; evidence suggests that RNA came before DNA in evolution. [1] The RNA World hypothesis proposes that life began with RNA molecules, before the emergence of DNA genomes and coded proteins. In DNA, the evolutionary substitution of thymine for uracil may have increased DNA stability and ...
Thymine could also be a target for actions of 5-fluorouracil (5-FU) in cancer treatment. 5-FU can be a metabolic analog of thymine (in DNA synthesis) or uracil (in RNA synthesis). Substitution of this analog inhibits DNA synthesis in actively dividing cells. Thymine bases are frequently oxidized to hydantoins over time after the death of an ...
These symbols are also valid for RNA, except with U (uracil) replacing T (thymine). [1] Apart from adenine (A), cytosine (C), guanine (G), thymine (T) and uracil (U), DNA and RNA also contain bases that have been modified after the nucleic acid chain has been formed. In DNA, the most common modified base is 5-methylcytidine (m5C).
RNA also uses a different set of bases than DNA—adenine, guanine, cytosine and uracil, instead of adenine, guanine, cytosine and thymine. Chemically, uracil is similar to thymine, differing only by a methyl group, and its production requires less energy. [47] In terms of base pairing, this has no effect. Adenine readily binds uracil or thymine.
The bases found in RNA and DNA are: adenine, cytosine, guanine, thymine, and uracil. Thymine occurs only in DNA and uracil only in RNA. Using amino acids and protein synthesis, [2] the specific sequence in DNA of these nucleobase-pairs helps to keep and send coded instructions as genes. In RNA, base-pair sequencing helps to make new proteins ...
Translation is accomplished by the ribosome, which links proteinogenic amino acids in an order specified by messenger RNA (mRNA), using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms and can be expressed in a simple table with 64 entries.