When Does Thymine Change to Uracil?

In RNA, uracil base-pairs with adenine and replaces thymine during DNA transcription

. Methylation of uracil produces thymine. In DNA, the evolutionary substitution of thymine for uracil may have increased DNA stability and improved the efficiency of DNA replication (discussed below).

Why does thymine changes to uracil in RNA?

The first three are the same as those found in DNA, but in RNA thymine is replaced by uracil as the base complementary to adenine. ... In DNA, however, uracil is readily produced by chemical degradation of cytosine, so having thymine as the normal base makes detection and repair of such incipient mutations more efficient.

Does uracil replace thymine?

Uracil is a nucleotide, much like adenine, guanine, thymine, and cytosine, which are the building blocks of DNA, except uracil replaces thymine in RNA. So uracil is the nucleotide that is found almost exclusively in RNA.