BCH5413 EXAM II QUESTIONS WITH ANSWERS

BCH5413 EXAM II QUESTIONS WITH |\ |\ |\ |\ |\




ANSWERS


Name some of the complexities of eukaryotic transcription when
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compared to prokaryotic transcription - CORRECT ANSWERS ✔✔*
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Eukaryotic transcription involves decondensing chromatin
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* The three main polymerases in eukaryotic systems are not
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sequence specific. They require transcription factors to recognize
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promoter sequence for them. In prokaryotes, te sigma factors are
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sequence specific to -10 region in the promoter
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* In eukaryotes, transcription and translation are
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compartmentalized and divided by the nucleus, transcripts need |\ |\ |\ |\ |\ |\ |\ |\


to be transported to cytoplasm upon creation
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* Eukaryotic organisms form pre-mRNA and then further process
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it to make mature mRNA
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What are the first three steps of pre-initiation complex formation
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(PIC formation)? - CORRECT ANSWERS ✔✔1) TBP (a subunit of
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TFIID) recognizes and binds the TATA box
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2) TFIIB binds and complexes with TFIID at the promoter
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3)Recruitment of RNA pol via association with TFIIF |\ |\ |\ |\ |\ |\ |\




What are the last three steps of PIC formation? - CORRECT
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ANSWERS ✔✔4) TFIIE Joins and associated with the formed PIC
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5) TFIIE Recruits RFIIH to from transcription initiation complex
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,6) TFIIH has kinase activity and phosphorylates the CTD of RNA
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pol II which promotes the transition from transcription initiation
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to elongation |\




What is the function of TFIID - CORRECT ANSWERS ✔✔TBP+13
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TAFS recognize and bind TATA Box and other core promoter
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elements, Helos to confiugre DNA to RNA POL II surface |\ |\ |\ |\ |\ |\ |\ |\ |\




General transcription factor |\ |\ |\




contains the TATA box binding proteins, TBP association factors
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(TAFs)
it nucleates PIC assembly though TBP binding to TATA sequence
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or TAF binding to other promoter sequences
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What is the function of TFIIB - CORRECT ANSWERS ✔✔It
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contributes to promoter selection, recruitment of TFIIF |\ |\ |\ |\ |\ |\ |\


association with RNA pol II |\ |\ |\ |\




How did the linker scanning experiment demonstrate that the
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TATA box is required for transcription while the GC boxes are not?
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- CORRECT ANSWERS ✔✔* mutated regions throughout the TK
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promoter |\




- Regions mutated within the TATA box destroyed promoter
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activity |\




- regions mutated in GC box regions affected transcription
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efficiency but did not abolish it. |\ |\ |\ |\ |\

, Name the two models for PIC assembly. What is the one similarity
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between the two? - CORRECT ANSWERS ✔✔1) Sequential
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assembly pathway |\ |\




2) RNA polymerase holoenzyme pathway
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Promoter recognition occurs by TFIID in both |\ |\ |\ |\ |\ |\




What is the function of the mediator? - CORRECT ANSWERS
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✔✔Just like it sounds |\ |\ |\ |\




1) transmits signals from transcription factors to polymerase
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2) functions as a coactivator
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3) is shown to interact with the CTD of RNA Pol II
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4) required for transcription activation
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In general overview, what are the steps necessary for transition
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from the PIC to the EEC? - CORRECT ANSWERS ✔✔0) initiation-
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formation of the PIC- initially transcribing complex (itc)- includes
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abortive initiation |\ |\




1) promoter clearance/ escape- early elongation complex (EEC)-
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promoter escape complete, nascent RNA stabiliy associates with
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transcription complex |\ |\




2) promoter proximal pausing- initially characterized in MYC gene
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but now found genome wide
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3) Productive elongation transcription elongation through
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nucleosomes


What does the ITC do? - CORRECT ANSWERS ✔✔Cycles through
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several cycles of abortive initiation, releasing large amounts of 2-
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3nt long RNA transcripts
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