BRAINCAKEEpigenetics
Epigenetics is the study of changes in gene expression that do not involve a change in the base sequence of DNA. These changes can be passed on when cells divide, and sometimes from parents to offspring.
Epigenetic changes are caused by chemical groups, often called epigenetic marks or tags, attached to DNA or to the histone proteins that DNA is wrapped around. The two main types are:
• DNA methylation: methyl groups added to cytosine bases in DNA
• histone modification: groups such as acetyl or methyl groups added to histones.
These marks change how tightly DNA is packed, and whether transcription factors and RNA polymerase can reach a gene. This switches genes on or off without changing the genetic code. The full set of epigenetic marks in a cell is called its epigenome.
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More in Gene Expression
- Gene Probes
- Control of Gene Expression
- Transcription Factors
- RNA Splicing
- DNA Methylation
- DNA Demethylation
- Euchromatin and Heterochromatin
- Histone Acetylation
All 39 lessons in Gene Expression · All Edexcel A-level Biology topics