Life sciences · Reference
What is epigenetics?
Epigenetics is the study of changes in gene activity that do not involve alterations to the underlying DNA sequence — changes that can switch genes on or off and may be passed on as cells divide.
Changing activity, not sequence
Epigenetics concerns changes that affect whether and how genes are expressed without altering the sequence of A, T, G, and C in the DNA. These changes act like switches and dimmers layered on top of the genome, turning genes on or off and tuning their activity. The term reflects this: "epi-" means "on top of", so epigenetics studies the marks that sit on top of the genetic code.
DNA methylation and histone modification
Two of the best-characterised epigenetic mechanisms are DNA methylation and histone modification. In DNA methylation, small chemical groups are added to the DNA, often reducing the expression of nearby genes.
Histones are proteins around which DNA is wound; chemical modifications to histones change how tightly the DNA is packaged, making genes more or less accessible for transcription. Together these mechanisms shape the pattern of gene expression in a cell.
Heritability and development
Some epigenetic marks are copied when a cell divides, so a pattern of gene activity can be maintained across cell generations — which is why a liver cell gives rise to more liver cells. Epigenetic regulation is central to development, allowing one genome to produce many specialised cell types, and marks can also change in response to environmental and developmental signals.
Research relevance
Epigenetics is an active research field linking the genome to cell behaviour, development, and the effects of the environment. Mapping epigenetic marks across the genome — the epigenome — generates large datasets that, like other genomic data, depend on shared standards and repositories to be comparable and reusable. This page describes the science of epigenetics and is not medical advice.
Key facts
At a glance
- Definition: changes in gene activity without DNA-sequence change
- Key mechanisms: DNA methylation, histone modification
- Effect: switches genes on or off, tunes expression
- Heritability: some marks copied through cell division
- Role: central to development and cell identity
- Study of all marks: the epigenome
Common questions
FAQ
What is epigenetics in simple terms?+
Epigenetics is about changes that affect whether genes are switched on or off without changing the DNA sequence. Chemical marks such as DNA methylation and histone modifications act like switches on top of the genome.
How is epigenetics different from genetics?+
Genetics studies the DNA sequence itself and how it is inherited. Epigenetics studies the marks layered on top of the DNA that control gene activity without altering that sequence.
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