Information and Inheritance-Control of gene expression in eukaryotes

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  • Created by: jessica
  • Created on: 20-03-13 13:12
What are the different ways that pre-transcription switches can work?
increase the amount of protein by increasing gene copy number is the most common process.
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Where is heterochromatin normally located?
At the telomeres and the centromeres
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How is the modulation of access of genes in transcription done?
by modification of the histones and DNA methylation. Chromatin re-modelling through histones tails covalent modifications. DNA methylation of specific CG sites close to gene promoters,histone modifications and DNA methylation are inheritable
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What can histones be used as?
chromatin re modeling tools, as they bend DNA, exposing the sequences to the transcription machinery,
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What are decoders?
proteins that recognise/bind to modified histone tails
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What does the binding of decoders to histone tails lead to?
‘closed’-condensed inactive or ‘open’-de-condensed active chromatin
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What does the transcriptional switch control?
the amount of primary transcript
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What are transcription switches?
specific DNA sequences or chromatin modifications recognized by transcription regulators.
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What is a promoter?
set of DNA sequences required to signal RNA polymerases where to start transcription e.g. TATA box situated upstream of the gene.
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What is an enhancer?
a DNA sequence ~200bp enhances the efficiency of transcription by binding it to transcription factors. Can be upstream or downstream or even within the gene.
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What is a silencer?
a localised nucleosome modification (DNA or histone) that keeps a chromatin region transcriptionally inactive.
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What is an insulator?
a DNA sequence that stops the action of an enhancer on the transcription of a downstream gene.
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What do insulators and silencers do?
limit the enhancer activity to specific genes and to transcriptionally active chromatin regions. An enhancer located between 2 genes can be used by activators to activate both genes at the same time.
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What are the specific structural motifs for specific binding to DNA and for the regulation of their activity?
Helix turn helix, helix loop helix, leucine zipper and zinc finger
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What are the two main deamination-based editing mechanisms?
Adenosine to Inosine, ADAR enzymes bind to exon sites to be edited that are complementary base-paired to a 3’ intron region. Cytosine to Uracil, Edited sites in introns or exons
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Card 2

Front

Where is heterochromatin normally located?

Back

At the telomeres and the centromeres

Card 3

Front

How is the modulation of access of genes in transcription done?

Back

Preview of the front of card 3

Card 4

Front

What can histones be used as?

Back

Preview of the front of card 4

Card 5

Front

What are decoders?

Back

Preview of the front of card 5
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