Explain how DNA methylation and histone acetylation affect chromatin structure and the regulation of transcription.

Explanation:

In histone acetylation, acetyl group (-COCH3) are attached to the lysines in the histone tails. When lysine are acetylated, their positive charges are neutral and the histone tails no longer binds to their neighboring nucleeosomes. Acetylation of Histones leads to activation of transcription because DNA is less tightly held to the nucleeosomes which makes DNA to easily bind to transcriptional machinery. But deaceylation leads to depression of transcription.

DNA methylation is the addition of an methyl group to the DNA bases, it inactive DNA. DNA methylation leads to long-term inactivation of genes could shutdown DNA transcription.

Thus, a dual mechanism, involving both DNA methylation and Histones deacetylation, can repress transcription.