#Question id: 4540
#Unit 3. Fundamental Processes
Transcription of eukaryotic genes can be repressed in various ways. These include the four mechanisms
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1. Competition |
a-Repression is caused by recruiting histone modifiers that alter nucleosomes in ways that inhibit transcript |
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2. Inhibition |
b-A repressor binds to a site on DNA beside an activator and interacts with that activator, occluding its activating region |
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3. Direct repression |
c-By binding to a site on DNA that overlaps the binding site of an activator, a repressor can inhibit binding of the activator to a gene and thus block activation of that gene. |
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4. Indirect repression |
d-A repressor binds to a site upstream of a gene and, by interacting with the transcriptional machinery at the promoter in some specific way, inhibits transcription initiation. |
#Question id: 4541
#Unit 3. Fundamental Processes
Mig1 recruits a “repressing complex” containing the Tup1 protein. This complex is recruited by many yeast DNA-binding proteins that repress transcription, including the alpha2 protein involved in controlling the mating-type specific. Tup1 also has counterparts in mammalian cells, choose correct mechanisms have been proposed to explain the repressing effect of Tup1.
I-Tup1 acts on nucleosomes either through recruiting histone deacetylases and/or by positioning a nucleosome at or near the transcription start site.
II-Tup1 interacts directly with the transcriptional machinery at the promoter and inhibits initiation.
#Question id: 4542
#Unit 3. Fundamental Processes
Repression of the GAL1 gene in yeast by Mig1, in the presence of glucose follows those steps;
I- Deacetylation of local nucleosomes
II-Recruiting the Tup1 repressing complex
III- Mig1 represses expression of GAL1
IV- Mig1 binds a site between the UASG and the GAL1 promoter
#Question id: 4543
#Unit 3. Fundamental Processes
Control of the activator NtrC- In that case, the signal (low ammonia levels) induces a kinase that phosphorylates NtrC. This is type of
A. Indirect signaling
B. Direct signaling
C. Is an example of a signal transduction pathway
#Question id: 4544
#Unit 3. Fundamental Processes
How is the binding of ligand to the extracellular domain communicated to the intracellular domain?
#Question id: 4545
#Unit 3. Fundamental Processes
Through which signal transduction pathway- controls the activators such as Jun, one of the activators that works at the interferon-beta enhancer