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MBBS QUESTION #10372
Question 1
Epigenetic modification of gene expression — such as DNA methylation at CpG islands, or histone acetylation and deacetylation — differs fundamentally from a genetic mutation in that epigenetic changes:
  • Permanently alter the underlying DNA nucleotide sequence itself
  • Alter gene expression (often heritable across cell divisions) without changing the underlying DNA nucleotide sequence✔️
  • Occur exclusively during meiosis and never in somatic cells
  • Cannot meaningfully influence disease risk or observable phenotype
Correct Answer Explanation
Epigenetic modifications regulate whether and how strongly a gene is expressed — for example, DNA methylation typically silences gene expression while histone acetylation typically promotes it — without altering the DNA base sequence itself, yet these patterns can be stably inherited through mitotic cell division and contribute significantly to disease processes such as cancer.