Chromatin Level

Question 1

What are the different forms of chromatins?

Answer 1

Nucleosome 
30nm chromatin Fiber 
Loop Domain 
Scoffold Protein 
Chromosome

Question 2

Compare Heterochromatin and Euchromatin

Answer 2

Hetero:

• highly compacted
• not accessible to enzymes involved in DNA transcription, replication or repair

Euk:

• less condensed
• active transcription

Question 3

Chromatin Remodelling

Answer 3

1. Nucleosomes consists of ~146bp of DNA wound around a histone core particle
2. N-terminal tails-> lysine rich-> (+)
3. Interact with negatively charged phosphate groups of sugar phosphate backbone
4. Increasing affinity of DNA for nucleosome surface, preventing accessibility of RNA ply and TFs

Question 4

How Is histone acetyle transferase (HATs) work?

Answer 4

1. Add acetyl group to lysine
2. Neutralises the positive charged histone tails
3. Less efa bt histone and DNA; DNA loosened and chromatin decondenses
4. Transcription machinery has easy access to genes in acetylated region

Question 5

How is histone deacetylases (HADCs) work?

Answer 5

1. Reforming chromatin to its default state -> condensed

Question 6

General description of Histone methylation

Answer 6

• covalently addition of a methyl group to 5’ cytosine

- 5’-CG-3’