Chromatin Structure Part 3 Flashcards
1
Q
chromosome looping
A
- how chromatin divided into functional domains within the nucleus
- forms loops and condenses a lot
2
Q
insulators
A
- Boundaries between domain of the gene and the enhancer (or silencer)
- the gene can no longer feel the activating (or repressing) effects
3
Q
domain boundaries
A
- special nucleoprotein structures formed by proteins at specific sites along the chromosome
4
Q
how is inappropriate activation avoided?
A
- organisms use DNA insulators to block activation of unrelated genes by nearby enhancers
5
Q
insulator proteins
A
- recruit histone acetyltransferases that acetylate flanking nucleosomes
- inhibits histone modifications required for the propagation of transcriptionally silent condensed chromatin
- prevents spread of heterochromatic DNA
6
Q
boundary elements
A
- relate structural organization of chromatin fiber into informational organization of the DNA
7
Q
position effects
A
- when genes relocated to new chromosomal environments by rearrangement or transformation
- modifies gene expression
8
Q
in vivo assay for boundary function
A
- determine if DNA sequences can protect a reporter gene from chromosomal position effects
9
Q
the site of insertion
A
- helps determine the level of expression of the transgene
10
Q
chromatin looping between elements facilitates transcription at submegabase level
A
- initiation of transcription involves physical interaction between gene regulatory elements such as promoters and enhancers
- may be separated by many kilo bases along the linear chromosome
- DNA loops out so enhancer can interact with promoter to initiate transcription
11
Q
topically associated domains (TADs)
A
- chromosomes are further segregated into these containing many chromatin loops
- separated by architectural proteins at their borders
12
Q
architectural proteins (APs)
A
- bend DNA and allow formation of loops
- also function as insulators
13
Q
chromosome territories (CTs)
A
- TADs further organized at entire chromosome level, forming these
- non randomly organized in the nucleus and occupy distinct regions
14
Q
lamin-associated domains (LADs)
A
- nucleus further segmented into different compartments
15
Q
repression facilitated by
A
- associated of genomic sequences with the inner nuclear lamina through lamin binding proteins
- gene position toward periphery of nucleus generally results in transcriptional repression
16
Q
transcriptional neighborhoods (TNs)
A
- contain a collection of transcriptional machinery
- provide an environment for initiation and hyper activation and maintenance of transcription
- multiple genes and regulatory elements founds within TNs
17
Q
directed chromatin movement
A
- local compaction of chromatin by architectural proteins
- looping out of specific genomic regions
18
Q
local compaction of chromatin by architectural proteins
A
- permits interaction between specific promoters and enhancers
- bend DNA into topological domains
- enables transcription of specific genes
19
Q
looping out of specific genomic regions
A
- to form long-range interactions with distal enhancers requires some chromatin slack
- decompact neighboring region
- previously interacting enhancer/promoter loops sacrificed to permit new loops
- allows interaction with promoters on different chromosomes
20
Q
domains are dynamic
A
- change under development time or physiological conditions to allow for change in gene expression
