DNA methylation

What is epigenetics?

Heritable changes in gene function, without changes to DNA sequence

What causes epigenetics?

Environmental factors and changes which inhibit transcription: Increased methylation of DNA, decreased acetylation of the associated histones - structures which package DNA into nucleosomes

What is DNA methylation?

Methyl groups added to DNA

What does methylation do?

Modifies the function of DNA, and suppresses the gene’s transcription, it alters the expression of genes in cells as they divide and become specialised

What does methylation make?

Barrier between RNA polymerase and structural genes, so less transcription happens - permanent and prevents cell from converting back into stem cell

How does methylation occur?

Addition of CH3 to cytosine bases

What does methylation stimulate?

Decreased acetylation of histones (which is what DNA wraps itself around - you want a loose wrap to allow RNA polymerase to get thru the gaps and transcribe

What does DNA acetylation?

Changes DNA structure

What are histones?

Positively charged proteins which associate with negatively charged DNA - decreased acetylation of histones increases their + charge so they bind to DNA tighter which switches off the gene

What do more acetyl groups?

More gaps for RNA polymerase to eat in as it increases the gap between DNA and histones