Which nitrogenous base is unique to RNA?

Uracil is the nitrogenous base that is unique to RNA. In RNA, uracil replaces thymine, which is found in DNA. The presence of uracil in RNA plays a critical role in the structure and function of RNA molecules. RNA is typically single-stranded, and the pairing of bases is essential for functions such as protein synthesis. While adenine, cytosine, and thymine are common to both DNA and RNA, thymine specifically is not present in RNA, making uracil distinct to that nucleic acid. The substitution of thymine with uracil helps to differentiate RNA from DNA, which is vital in processes such as transcription and translation in cellular biology.