Chromatin Structure Part 3 Flashcards Preview

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Flashcards in Chromatin Structure Part 3 Deck (20):
1

chromosome looping

- how chromatin divided into functional domains within the nucleus
- forms loops and condenses a lot

2

insulators

- Boundaries between domain of the gene and the enhancer (or silencer)
- the gene can no longer feel the activating (or repressing) effects

3

domain boundaries

- special nucleoprotein structures formed by proteins at specific sites along the chromosome

4

how is inappropriate activation avoided?

- organisms use DNA insulators to block activation of unrelated genes by nearby enhancers

5

insulator proteins

- 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

boundary elements

- relate structural organization of chromatin fiber into informational organization of the DNA

7

position effects

- when genes relocated to new chromosomal environments by rearrangement or transformation
- modifies gene expression

8

in vivo assay for boundary function

- determine if DNA sequences can protect a reporter gene from chromosomal position effects

9

the site of insertion

- helps determine the level of expression of the transgene

10

chromatin looping between elements facilitates transcription at submegabase level

- 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

topically associated domains (TADs)

- chromosomes are further segregated into these containing many chromatin loops
- separated by architectural proteins at their borders

12

architectural proteins (APs)

- bend DNA and allow formation of loops
- also function as insulators

13

chromosome territories (CTs)

- TADs further organized at entire chromosome level, forming these
- non randomly organized in the nucleus and occupy distinct regions

14

lamin-associated domains (LADs)

- nucleus further segmented into different compartments

15

repression facilitated by

- 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

transcriptional neighborhoods (TNs)

- 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

directed chromatin movement

- local compaction of chromatin by architectural proteins
- looping out of specific genomic regions

18

local compaction of chromatin by architectural proteins

- permits interaction between specific promoters and enhancers
- bend DNA into topological domains
- enables transcription of specific genes

19

looping out of specific genomic regions

- 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

domains are dynamic

- change under development time or physiological conditions to allow for change in gene expression