Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
This refers to a biochemical process where a methyl group is added to cytosine bases in DNA. This usually results in reduced gene activity because it prevents transcription factors from accessing the DNA.
Related terms
DNA Methyltransferase: The enzyme responsible for adding a methyl group to DNA.
CpG Island: A region with a high frequency of cytosine and guanine base pairs, often found near gene promoters and frequently targeted for methylation.
Demethylation: The removal of a methyl group from DNA, which can increase gene activity.