Chromatin structure

Question 1

What modifications to core histone N-terminal tails can you make?

Answer 1

1. Acetylation of lysines

2. Methylation of lysines and arginines

Question 2

What is histone acetylation associated with?

Answer 2

Creating binding sites for transcription activators

Question 3

What does methylation do?

Answer 3

Create binding sites for:

1. Transcriptional repressors
2. Transcriptional activators

Question 4

How do transcriptional activators work in chromatin?

Answer 4

1. Selective nucleosome remodelling
2. Selective histone removal
3. Selective histone replacement
4. Selective histone modification

Question 5

How do transcriptional repressor proteins work in chromatin?

Answer 5

1. Compete for DNA binding
2. Mask activation surfaces
3. Recruit chromatin remodelling complexes
4. Recruitment of histone deacetylases
5. Direct interaction with general transcription factors
6. Recruitment of histone methyl transferase

Question 6

What is the purpose of x chromosome inactivation in mammals?

Answer 6

So there is equal levels of X-chromosome derived products in males and females

Question 7

What is Xist?

Answer 7

a non coding RNA

Question 8

What is Xic?

Answer 8

X inactivation centre

Question 9

What does Xist recruit

Answer 9

Histone modifying enzymes
Polycomb group components
PRC 1, PRC2