Basis of differentiation

DNA methylation

Histone acetylation

Definition

DNA methylation is the epigenetic modification where DNA bases become modified to methylated bases with the assistance of methyl transferase

Histone acetylation is the epigenetic modification where specific residues of the histone proteins are acetylated with the assistance of acetyl transferases

Occurrence 

Occurs in DNA 

Occurs in selected amino acid residues of histone proteins 

Result

Results in methylation or hyperpigmentation of DNA bases, causing the inactivation of genes 

Results in the acetylation of selected amino acid residues leading to chromosome decondensation

Enzymes involved 

DNA methyl transferase

Histone acetyl transferase 

Residues

The cytosine residues get methylated

The lysine residues get acetylated

Chemical modification

Adding the methyl group donated by S-adenosine methionine 

Adding acetyl groups through the acetyl coenzyme A donor 

Transcriptional regulation

Inhibits or inactivates transcription by silencing genes or inactivating regulatory regions

Activates or promotes transcription by decondensing DNA to aid in transcription