Final answer:
Cytosines can be removed from the genome through epigenetic mechanisms such as DNA methylation by DNA methyltransferases and histone deacetylation by histone deacetylases. This process can silence genes and is reversible, providing therapeutic strategies for conditions like cancer. Option B is correct.
Step-by-step explanation:
The question you're asking about revolves around the mechanisms by which cytosines can be removed from the genomic DNA. The process that primarily facilitates this alteration is through epigenetic mechanisms, including DNA methylation and histone modification.
Essential players in this process are DNA methyltransferases, which add methyl groups to the cytosine in CpG islands, often leading to gene silencing. Another key protein involved is histone deacetylase, which removes acetyl groups from histones, leading to tighter packing of DNA and reduced gene expression.
These mechanisms are reversible, which offers therapeutic potential in cases like cancer, where epigenetic alterations can silence genes crucial for normal cell function.