Epigenetic's
- Created by: Emilyburkee
- Created on: 04-01-23 16:27
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- Describe factors that affect the affinity of general transcription factors for DNA and explain how this affects transcription rates.
- transcriptional activators
- promote regulators binding
- also promotes RNA pol binding
- recurit co activators
- histone modifying enzymes
- ATP-dependent chromatin remodelling complexes
- histone chaperones
- structure of Chromatin
- can prevent access to promotors if wound tightly around Histones
- neg charged Sug-pi backbone on DNA interacts with P+ DNA
- Cis regulatory sequences = Face inwards
- therefore Regulators bind with lower aff
- Changes in shape of binding site due to associated protein binding
- Changes in shape of binding site due to associated protein binding
- therefore Regulators bind with lower aff
- How can the structure of chromatin change
- Nucleosome slidding
- needs : Histone chaperones, ATP-dep remodllers
- NAP-1, SW12
- needs : Histone chaperones, ATP-dep remodllers
- Nucleosome eveiction
- ATP dep, occurs alongside exchnage
- Histone variant exchange
- ATP dep remodllers and chaperones
- histone tail mods
- changes in A.A
- (mainly lysine)
- sumoylation and Ubq ( 0Q)
- arginine- always maintains +, can be methylated
- Serine- mainly Pi
- (mainly lysine)
- histone tails help grip DNA
- Effect = diff binding of mediator or GTFs
- changes in A.A
- some mods compete as thier occur next to or at the smae A.A
- Nucleosome slidding
- can prevent access to promotors if wound tightly around Histones
- Effects on multiple genes
- 3D bending + binding to an insulator = prevent transcription initiation or progression
- DNA methylation
- Mainly T + C
- mainly done by DNMTs
- DNMT3a+b = de novo
- DNMTs1 adds to daughter DNA during DNA synth
- Occur a-lot in CpG islands
- regulate tissue spef gene expression
- Genomic imprinting
- X-chromosome in activation
- how do they effect expression
- less nucleosomes
- Close to TSS
- inc TF binding sites
- METH at exon 1 = recuirts TF
- open up and recruit enzymes
- recruits Inhibitory TF, disrupts TF binding, if at promotor = silencing
- Epigenetic Cross talk
- readers = mediator complex
- Writers = enzymes that change mods
- erasers= enzymes that remove mod eg de...
- reg proteins bind to a CIS-REG seq
- req writers
- reader recognises mod
- writer binds to reader= next mod on next chromosome
- reader recognises mod
- req writers
- expression Histone tails meth= inhibit DNMT
- inhibition - meth of DNA + tails = Mb Proteins= rec Tail modifers
- break system
- Barrier sequences= can stop the spread of changes
- Tethering a chromatin domain to a large fixed site, Strong binding barrier protein. c) mediator complex containing chromatin modifying enzymes
- Barrier sequences= can stop the spread of changes
- transcriptional activators
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