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4.1 Prokaryotic Transcription — Test 1
Q1. Polycistronic transcription units are common in:✓ Bacteria
Q2. 'Promoter escape' (promoter clearance) in transcription means:✓ Movement of RNA polymerase away from the promoter into elongation
Q3. The role of Rho protein in transcription termination is:✓ Helicase activity that unwinds the RNA:DNA hybrid to release the transcript
Q4. Coupled transcription and translation occurs in:✓ Prokaryotes
Q5. Which subunit of prokaryotic RNA polymerase recognises the promoter?✓ σ (sigma) subunit
Q6. Which sigma factor transcribes housekeeping genes in E. coli?✓ σ70
Q7. Chemical-mediated introduction of naked DNA into a bacterial cell is called:✓ Transformation
Q8. Transcription by E. coli RNA polymerase requires all the following EXCEPT:✓ Rho factor (always)
Q9. The core RNA polymerase is guided to the transcription start site by which factor?✓ Sigma
Q10. Which statements correctly describe transcription? (best combined answer)✓ RNA synthesis initiates de novo (no primer); sigma ensures accurate bacterial initiation; eukaryotic mRNA is capped with a modified G
Q11. Which factor ensures stable binding of RNA polymerase at the promoter?✓ Sigma factor
Q12. Which sigma factor directs the core polymerase to the -12(GC)/-24(GG) class of promoters (note: distinct from -10/-35)?✓ σ54
Q13. Which best describes the helicase-like function in transcription initiation?✓ Separation of the two DNA strands to give polymerase access (open complex)
Q14. Which statement about prokaryotic transcription termination is correct?✓ Intrinsic termination involves a stem-loop (hairpin) in the RNA transcript
Q15. The E. coli core RNA polymerase has the subunit composition:✓ α₂ββ'ω
Q16. The bacterial promoter consensus elements recognised by σ70 are located near:✓ -10 (Pribnow/TATAAT) and -35 (TTGACA)
Q17. Rifampicin inhibits bacterial transcription by binding the:✓ β subunit of RNA polymerase
Q18. Intrinsic (rho-independent) terminators are characterised by:✓ A GC-rich hairpin followed by a run of uridines in the RNA
Q19. During elongation, the bacterial RNA polymerase that has released sigma is called the:✓ Core enzyme