Histone Modifications

Question 1

Histone octamer

Answer 1

Tightly packed into globular protein that interacts with DNA (nucleosome); each histone has N-terminus tail that protrudes from protein which forms intermolecular contacts with adjacent nucleosomes that regulate chromosome compaction

Question 2

Histone modifications

Answer 2

chemical modifications to amino acid side chains in N-terminal tail of histone that influence interactions between nucleosomes to change compaction

Question 3

Acetylation at H3

Answer 3

H3K4, H3K9, H3K27; associated with euchromatin/transcriptional activation; histone acetyltransferase adds acetyl group, histone deacetylase removes acetyl group

Question 4

Methylation at H3

Answer 4

H3K4; associated with euchromatin/transcriptional activation | H3K9, H3K27; promotes heterochromatin/transcriptional inactivation; methyltransferase/histone demethylase