#Question id: 4483
#Unit 3. Fundamental Processes
TAF42 and TAF62 from Drosophila form a structure similar to that of the
#Question id: 4484
#Unit 3. Fundamental Processes
Match General Transcription Factors with their functions;
|
i. TAFs |
A. Appears to regulate the binding of TBP to DNA. It does this using an inhibitory flap that binds to the DNA-binding surface of TBP, another example of molecular mimicry. This flap must be displaced for TBP to bind TATA. |
|
ii. TFIIB |
B. Insert into the RNA-exit channel and active center cleft of Pol II in a manner analogous to the sigma region 3/4 linker in the bacterial case. |
|
iii. TFIIH |
C. As an ATP-driven translocator of double-stranded DNA. |
|
iv. TFIIF |
D. This two-subunit (in humans) factor associates with Pol II and is recruited to the promoter together with that enzyme. |
#Question id: 4485
#Unit 3. Fundamental Processes
In multicellular organisms, regulatory sequences can spread thousands of nucleotides from the promoter—both upstream and downstream—and can be made up of tens of regulator binding sites. Often, these binding sites are grouped in units called_?
#Question id: 4486
#Unit 3. Fundamental Processes
Activators can recruit factors needed for polymerase to initiate or elongate transcription. In all of these functions, the activator is merely recruiting proteins to the promoter. In bacteria, RNA polymerase is the only protein that needs to be recruited; this is not the case in eukaryotes. Indeed, in eukaryotes, a given activator might work in all three ways:
|
1. Recruitment of nucleosome modifiers and remodelers |
i. “open” the promoter |
|
2. Recruitment of general transcription factors and mediators |
ii. That stimulate Pol II initiation and elongation |
|
3. Recruitment of protein complexes |
iii. To recruit PTEFb/SEC |
#Question id: 4487
#Unit 3. Fundamental Processes
Choose correct statements about nucleosome modifiers
#Question id: 4488
#Unit 3. Fundamental Processes
One component of thecomplex bears bromodomains and thus binds to acetylated nucleosomes better than to unacetylated nucleosomes. Thus, a gene bearing acetylated nucleosomes at its promoter will likely have a higher affinity for the transcriptional machinery than one with unacetylated nucleosomes.