Epigenetic Modifications

Epigenetic Modifications

Modifications that change the expression of genes without changing the sequence of DNA.

Nucleosome

147 Base Pairs wrapped around 8 histones.

Euchromatin

Loose chromatin

Which chromatin transcribes easier

If its more loose

Heterochromatin

Hetero is different, this is harder to transcribe and is wound more tightly

Chromatin Remodeling

Changing structure of chromatin due to epigenetic modifications.

Histone Acetylation

Acetyl groups are positive and negate the charge of the DNA, making the chromatin looser.

Amino Terminal Tails

Histones have these tails sticking out.

Target of acetylation

Lysine in the amino terminal tail

What is the Enzyme that acetylates

Histone Acetyl Transferases

Histone Deacetylases

Tightens

DNA methylation

Methyl group is added to form 5- methylcytosine

Methyl group

Physical barrier to inhibit the binding of transcription factors.

How do methylated cytosines tighten the chromatin

They form methyl groups that block transcription factors and attract histone deacetylases

DNA Methyl Transferase

Methylates Cytosines

What specifically is the target of Methylation

C followed by G

CpG Islands

CG rich regions