Epigenetic regulation of chromatin Flashcards
1
Q
How much does chromatin compact dna?
A
20microns
2
Q
How does chromatin affect gene expression?
A
TF and Pol accessibility
3
Q
heterochromatin
A
peripheral and nucleoli
4
Q
nucleosomes
A
- self-organising
- beads on a string under EM
- basic, +ve central globular domain
- stabilised by EA
5
Q
H1
A
- higher order disorganised aperiodic crystal tertiary packaging
- less accessible in interphase
6
Q
secondary chromatin
A
- 30nm fibre
- folding
7
Q
epigenetic
A
- centrosome and ori function
8
Q
CENP-A
A
- H3 variant
- DAPI staining and Abs
9
Q
histone code
A
- N-terminal PTMs
- Ser, Lys, Thr, Arg (amino/hydroxyl side chains)
- change local chromatin
10
Q
erasers recruited by
A
TFs, transcription, ncRNAs
11
Q
local effects
A
protein recruitment
12
Q
active genes:
A
- H3K4me3
- H3/H4ac
- H2BK120ub1
- H3K79me3
- H3K36me3
13
Q
H3K4me3
A
- SetD2 methylates
- blocks DNMT
- ADD-inactivation via MT-domain
- NURF recruitment
14
Q
NURF
A
- chromatin remodeller (ATP-expensive)
- reduces stability
- exposes from chromosome body
15
Q
H3K36me3
A
HDAC binding for long introns
16
Q
Repressed genes
A
- H3K9me3
- H3K27me3
- H2AK119ub1
17
Q
H3K9me3
A
- antisense m/ncRNA directs RITSC to nascent transcript
- multi-subunit CLRC interacts with RITSC
- active Clr4 methylates
- Heterochromatin protein 1 condenses chromatin
18
Q
DNA methylation
A
- chemically inert
- recruitment purposes
19
Q
H2A.B
A
highly methylated intragenic DNA at actively transcribed loci (Chen at al., 2014)
20
Q
erasing
A
- TET oxidation
- base excision repair
21
Q
How does methylation inhibit transcription
A
- TFs blocked
- MBDs + DNMTs recruit HDACs
22
Q
MBDs
A
methyl-CpG-binding domains
23
Q
5meC preservatioon
A
- UHRF1 SRA domain binds hemimethylated CpG
- recruits DNMT1 via BD
24
Q
histone restoration in D.melanogaster
A
- PRC2 polycomb allosterically activates
- blocking domains prevent inappropriate spread
