Biology
Define DNA methylation
![](https://d22o6al7s0pvzr.cloudfront.net/images/bookrags/qa/avatars/School/Stack_of_Books.png)
Asked by
bookragstutor
Last updated by
Jill W
DNA methylation is when the methyl group is added to the 5 position of the cytosine pyrimdine ring (number 6 nitrogen of the adenine purine ring). This can happen naturally through cell division. DNA methylation is a chief component in gene expression.