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. Additionally, it is essential in the development of antiviral and anticancer drugs, as modifications to cytosine can inhibit the replication of viruses or cancer cells. In epigenetics, cytosine methylation is a key mechanism for regulating gene activity, making it important for understanding diseases and developmental processes.