DNA methylation

Definition

DNA methylation is an epigenetic mechanism involving the addition of a methyl group to the DNA molecule, typically at cytosine bases. This modification can affect gene expression by altering the accessibility of the DNA to transcription factors and other proteins.

5 Must Know Facts For Your Next Test

1. DNA methylation is commonly associated with the repression of gene expression.
2. In prokaryotes, DNA methylation often plays a role in protecting against viral DNA through restriction-modification systems.
3. Methylation patterns are heritable but can also be influenced by environmental factors.
4. Changes in DNA methylation can lead to genomic instability and have been linked to various diseases, including cancer.
5. DNA methyltransferases (DNMTs) are enzymes responsible for adding methyl groups to DNA.

Review Questions

• How does DNA methylation typically affect gene expression?
• What role does DNA methylation play in prokaryotic defense mechanisms?
• What enzyme is responsible for adding methyl groups to DNA?

Related terms

Epigenetics:

The study of heritable changes in gene expression that do not involve changes to the underlying DNA sequence.

Restriction-Modification System: A system used by bacteria to protect against invading viral DNA, involving both restriction enzymes and DNA methyltransferases.

DNA Methyltransferase (DNMT): An enzyme that catalyzes the transfer of a methyl group to specific sites on the DNA molecule.