What replaces thymine when RNA is synthesized from DNA?

When RNA is synthesized from DNA, uracil replaces thymine. In DNA, the base thymine pairs with adenine. However, during the transcription process where RNA is synthesized, thymine is not present in RNA. Instead, uracil takes its place and pairs with adenine during the formation of RNA strands. This shift is significant because it reflects the distinct roles and structures of DNA and RNA, as well as the differences in nucleotide components between the two types of nucleic acids.

The presence of uracil in RNA instead of thymine is one of the key differences that set RNA apart from DNA, emphasizing the functional adaptations of RNA in various biological processes, such as protein synthesis.