Cytosine is widely used in molecular biology and genetic research as a fundamental component of DNA and RNA. It plays a critical role in the study of genetic coding, mutations, and gene expression. In biotechnology, cytosine is utilized in the synthesis of oligonucleotides for PCR, sequencing, and gene editing techniques like CRISPR. It is also essential in the development of antiviral and anticancer drugs, as modifications to cytosine can influence the efficacy of these treatments. Additionally, cytosine derivatives, such as cytosine arabinoside, are used in chemotherapy to treat certain cancers by inhibiting DNA synthesis in rapidly dividing cells.