This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
Methylation of cytosine is associated with 
Select and explain. 
A. Mutation, B. Increased expression of gene, C. Decreased expression of gene, D. No effect
C: Decreased expression of gene
Answer: C: Decreased expression of gene 
Explanation: DNA methylation is essential for normal development and is associated with a number of key processes including genomic imprinting, X-chromosome inactivation, repression of transposable elements, aging, and carcinogenesis. Two of DNA's four bases, cytosine and adenine, can bemethylated Ref satyanarayana 4e