Which term refers to heritable changes in gene expression without changes to the DNA sequence?

• A. Genomics
• B. Mutation
• C. Transcriptomics
• D. Epigenetics

Answer: (D)

Epigenetics refers to heritable changes in gene expression that occur without changing the DNA sequence. These changes are driven by chemical marks and structural alterations to DNA and histone proteins, such as DNA methylation and histone modifications, which can switch genes on or off. Because these marks can be preserved through DNA replication, they can be passed to daughter cells during cell division and, in some cases, to future generations. This allows the organism to respond to development and environment without altering the actual genetic code. Examples include X-chromosome inactivation and genomic imprinting, where gene activity depends on epigenetic marks rather than sequence changes. In contrast, a mutation is a change in the DNA sequence itself, genomics is the study of the genome, and transcriptomics examines RNA expression levels.