Question

biological reason for the presence of uracil in rna but not in dna

Answer 1

RNA was considered to be the first genetic material. However, it was not stable enough and was prone to mutation. The presence of Uracil was one of the reasons why RNA was unstable and led to frequent mutations. Thus, over time, RNA evolved and thus produced DNA which was more stable due to its double-stranded nature and the presence of Thymine instead of Uracil. Therefore, DNA became the unviersally accepted genetic material.