BCH3033 Biochemistry 1 Chapter 26.5 PDF

BCH3033: Biochemistry 1 Chapter 26.5 04.12.2024 Donella Beckwith, Ph.D. [email protected] 1 Question 12 Which factor is NOT associated with the function of promoters? A. different σ factors in E. coli specific for specific promoters B. requirement of several transcription factors to properly positio...

BCH3033: Biochemistry 1 Chapter 26.5 04.12.2024 Donella Beckwith, Ph.D. [email protected] 1 Question 12 Which factor is NOT associated with the function of promoters? A. different σ factors in E. coli specific for specific promoters B. requirement of several transcription factors to properly position Pol II at the promoter in eukaryotes C. binding of the E. coli core RNA polymerase, directed by its σ factor, to a promoter D. Pol II in eukaryotes having strict specificity for the TATA box and Inr sequence 2 Response Which factor is NOT associated with the function of promoters? D. Pol II in eukaryotes having strict specificity for the TATA box and Inr sequence TATA-binding protein (TBP), not Pol II, binds to the TATA box. TBP is bound, in turn, by the transcription factor TFIIB. The TFIIB-TBP complex is next bound by another complex consisting of TFIIF and Pol II. The Inr sequence is straddled on both ends by TFIID subunits, which act as a scaffold to direct binding of Pol II. 3 Critical Question Specifically, what causes the changes in phosphorylation (in the image below) when going from Initiation to elongation? Just answer the 2 questions below. – – What phosphorylates Ser2? (kinase) Hint: page 969 in your book What dephosphorylates Ser5? (phosphatase) NO SENTENCE ANSWERS, just type: 1) answer 2) answer 4 Question 13 Which is NOT a phase of eukaryotic transcription? A. B. C. D. E. elongation assembly preparation termination initiation 5 Response Which is NOT a phase of eukaryotic transcription? C. preparation The process of transcription by Pol II can be described in terms of several phases — assembly, initiation, elongation, and termination — each associated with characteristic proteins. 6 Question 15 What is removed from the RNA primary transcript in order to produce mRNA? A. B. C. D. E. TATA boxes recombination signal sequences introns promoter sites polyadenylation 7 Response What is removed from the RNA primary transcript in order to produce mRNA? C. introns In a process called RNA splicing, the introns are removed from the pre-mRNA, and the exons are spliced together to form a continuous sequence that specifies a functional polypeptide. 8 Question 16 Which factor is NOT a typical modification found in a eukaryotic mRNA? A. B. C. D. polyadenylation of the 3′ end addition of a 5′ cap exon addition intron removal 9 Response Which factor is NOT a typical modification found in a eukaryotic mRNA? C. exon addition Following the removal of introns, the exons that remain are joined together to form a mature, functional RNA. 10 Question 17 What is a 5′ cap, structurally? A. 7-methylguanosine on the 5′ end of RNA B. a sequence of adenosine residues added to the 5′ end of the RNA C. 3-methyluracil added to the 5′ end of the RNA D. 5-methylguanosine on the 3′ end of the RNA E. methylation of the 5′ base of RNA, preventing further addition of bases 11 Response What is a 5′ cap, structurally? A. 7-methylguanosine on the 5′ end of RNA Most eukaryotic mRNAs have a 5′ cap, a residue of 7methylguanosine linked to the 5′-terminal residue of the mRNA through an unusual 5′,5′-triphosphate linkage. 12 Question 18 The 5′ cap: A. B. C. D. is composed of 4-methylguanosine. is attached via a 5′,3′-triphosphate linkage. protects the rRNA from degradation. participates in binding of the mRNA to the ribosome to initiate translation. E. All of the answers are correct. 13 Response The 5′ cap: D. participates in binding of the mRNA to the ribosome to initiate translation. The 5′ cap is a residue of 7-methylguanosine linked to the 5′terminal residue of the mRNA through an unusual 5,5triphosphate linkage. The cap helps protect mRNA from ribonucleases and participates in binding of the mRNA to the ribosome to initiate translation. 14 Question 26 Posttranscriptional modifications are NOT made to bases in: A. B. C. D. E. ribosomal RNA. messenger RNA. transfer RNA. silencing RNA. All of these can have posttranscriptional modifications. 15 Response Posttranscriptional modifications are NOT made to bases in: E. All of these can have posttranscriptional modifications. Posttranscriptional processing is not limited to mRNA. For example, both ribosomal and transfer RNAs are derived from longer precursors. These RNAs may also contain a variety of modified nucleosides. 16