Transcription (RNA synthesis) MCQs With Answer

Transcription (RNA synthesis) MCQs With Answer
Transcription, the process of RNA synthesis from a DNA template, is central to gene expression and drug-target interactions studied in B. Pharm. This introduction reviews key concepts: RNA polymerases, promoter architecture (TATA box, -10/-35 elements), initiation factors, elongation dynamics, termination mechanisms (rho-dependent/independent), and co-/post-transcriptional processing (capping, splicing, polyadenylation). Understanding regulatory elements, transcription factors, chromatin modifications, and experimental assays (RT-PCR, Northern blot, RNA-seq) is essential for pharmacology and biotechnology applications. Clear knowledge of these topics aids drug development, antibiotic mechanisms, and gene expression analysis. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is transcription in molecular biology?

• Synthesis of DNA from an RNA template
• Synthesis of RNA from a DNA template
• Translation of mRNA into protein
• Replication of the entire genome

Correct Answer: Synthesis of RNA from a DNA template

Q2. Which enzyme catalyzes RNA synthesis in bacteria?

• DNA polymerase III
• Reverse transcriptase
• RNA polymerase holoenzyme
• Ribonuclease H

Correct Answer: RNA polymerase holoenzyme

Q3. Which eukaryotic RNA polymerase is primarily responsible for synthesizing mRNA?

• RNA polymerase I
• RNA polymerase II
• RNA polymerase III
• RNA polymerase IV

Correct Answer: RNA polymerase II

Q4. What is the consensus sequence of the bacterial -10 promoter element (Pribnow box)?

• TATAAT
• TTGACA
• CAAT
• AAUAAA

Correct Answer: TATAAT

Q5. What is the primary role of the sigma factor in bacterial transcription?

• Catalyze phosphodiester bond formation
• Recognize promoter sequences and initiate transcription
• Terminate transcription at hairpin loops
• Add a 5′ cap to the RNA

Correct Answer: Recognize promoter sequences and initiate transcription

Q6. Approximately where is the eukaryotic TATA box located relative to the transcription start site?

• ~100 bp downstream of +1
• ~25 bp upstream of +1
• At the +1 transcription start site
• Within the first exon

Correct Answer: ~25 bp upstream of +1

Q7. Which nucleotide species is directly incorporated at the +1 position during initiation of transcription?

• A deoxynucleotide triphosphate (dNTP)
• An NTP complementary to +1 with a 5′ triphosphate
• A free nucleotide monophosphate (NMP)
• A capped nucleotide added later

Correct Answer: An NTP complementary to +1 with a 5′ triphosphate

Q8. Which termination mechanism requires the rho protein in bacteria?

• Intrinsic termination by hairpin and U-tract
• Rho-dependent termination
• Transcriptional attenuation
• Translation-dependent termination

Correct Answer: Rho-dependent termination

Q9. Intrinsic (rho-independent) termination in bacteria typically involves which features?

• A G-rich tract followed by poly-C
• Hairpin formation in RNA followed by a U-rich sequence
• Protein binding to an upstream element
• Polyadenylation signal AAUAAA

Correct Answer: Hairpin formation in RNA followed by a U-rich sequence

Q10. Which statement describes polycistronic mRNA?

• A single mRNA that encodes multiple proteins, common in prokaryotes
• An mRNA that has multiple 5′ caps
• A eukaryotic mRNA with multiple poly(A) tails
• An mRNA translated only in mitochondria

Correct Answer: A single mRNA that encodes multiple proteins, common in prokaryotes

Q11. Which modification is added co-transcriptionally to the 5′ end of eukaryotic pre-mRNA?

• Polyadenylation
• 5′ cap (7-methylguanosine)
• RNA editing by ADAR
• Spliceosome-mediated intron removal

Correct Answer: 5′ cap (7-methylguanosine)

Q12. What hexamer sequence commonly signals cleavage and polyadenylation of pre-mRNA in eukaryotes?

• TATAAA
• TTGACA
• AAUAAA
• AUGGCU

Correct Answer: AAUAAA

Q13. The spliceosome is primarily composed of which small nuclear ribonucleoproteins?

• rRNA
• snRNPs (U1, U2, U4, U5, U6)
• ribosomal proteins
• telomerase components

Correct Answer: snRNPs (U1, U2, U4, U5, U6)

Q14. What is the primary biological significance of alternative splicing?

• To degrade faulty mRNAs
• To increase proteome diversity from a single gene
• To add caps to mRNA
• To polyadenylate rRNA

Correct Answer: To increase proteome diversity from a single gene

Q15. Where does major mRNA processing occur in eukaryotic cells?

• In the cytosol before export
• In the mitochondria
• In the nucleus during and after transcription
• On the ribosome during translation

Correct Answer: In the nucleus during and after transcription

Q16. Proteins that bind promoter DNA and recruit RNA polymerase II are called what?

• General transcription factors (GTFs)
• Histone methyltransferases
• Ribosomal subunits
• DNA ligases

Correct Answer: General transcription factors (GTFs)

Q17. What is the function of the Mediator complex in eukaryotic transcription?

• Terminate transcription at poly(A) sites
• Link regulatory transcription factors with RNA polymerase II to facilitate transcription initiation
• Process rRNA in the nucleolus
• Unwind DNA during replication

Correct Answer: Link regulatory transcription factors with RNA polymerase II to facilitate transcription initiation

Q18. How does DNA methylation of promoter CpG islands typically affect transcription?

• Activates transcription by recruiting RNA polymerase
• Silences transcription by preventing factor binding
• Converts mRNA into rRNA
• Has no effect on gene expression

Correct Answer: Silences transcription by preventing factor binding

Q19. Which histone modification is most commonly associated with transcriptional activation?

• Histone deacetylation
• Histone ubiquitination at H2A K119
• Histone acetylation (e.g., H3K9ac)
• DNA intercalation

Correct Answer: Histone acetylation (e.g., H3K9ac)

Q20. In which cellular context does translation begin while transcription is still in progress?

• Eukaryotic nucleus
• Prokaryotic cytoplasm
• Mitochondrial matrix of eukaryotes only
• During RNA processing in the nucleolus

Correct Answer: Prokaryotic cytoplasm

Q21. Which antibiotic specifically inhibits bacterial RNA polymerase initiation by binding the β-subunit?

• Tetracycline
• Rifampicin (rifampin)
• Streptomycin
• Chloramphenicol

Correct Answer: Rifampicin (rifampin)

Q22. Which drug intercalates into DNA and blocks both transcription and replication elongation?

• Actinomycin D
• Ampicillin
• Puromycin
• Cycloheximide

Correct Answer: Actinomycin D

Q23. Bacterial RNA polymerase proofreading and rescue from backtracking is aided by which factors?

• TATA-binding protein (TBP)
• GreA and GreB transcription factors
• snRNPs
• Poly(A) polymerase

Correct Answer: GreA and GreB transcription factors

Q24. Approximately how many base pairs are held open in the transcription bubble during elongation?

• ~5 bp
• ~17 bp
• ~50 bp
• ~100 bp

Correct Answer: ~17 bp

Q25. What is the consensus sequence of the bacterial -35 promoter element?

• CAAT
• TTGACA
• AAUAAA
• TATAAA

Correct Answer: TTGACA

Q26. The transcription start site is commonly referred to as which position?

• -10
• -35
• +1
• +10

Correct Answer: +1

Q27. Besides the TATA box, which core promoter elements can direct RNA polymerase II transcription?

• Promoter-proximal pausing elements only
• Inr (initiator) and DPE (downstream promoter element)
• Poly(A) tail signals
• Rho-dependent terminators

Correct Answer: Inr (initiator) and DPE (downstream promoter element)

Q28. Which statement best describes enhancer elements?

• They must be immediately adjacent to the TSS to function
• They increase transcription and can function at a distance and in either orientation
• They always repress transcription
• They are only found in prokaryotes

Correct Answer: They increase transcription and can function at a distance and in either orientation

Q29. What is a transcriptional silencer?

• An RNA structure that stops translation
• A DNA element that reduces transcription when bound by repressor proteins
• A chemical that alkylates DNA
• A promoter with high basal activity

Correct Answer: A DNA element that reduces transcription when bound by repressor proteins

Q30. TFIIH is a general transcription factor with which key activities?

• Histone methyltransferase and ligase activity
• Kinase for RNA pol II CTD phosphorylation and helicase activity for promoter opening
• Polyadenylation and capping
• tRNA charging and modification

Correct Answer: Kinase for RNA pol II CTD phosphorylation and helicase activity for promoter opening

Q31. Which RNA polymerase transcribes most ribosomal RNA (rRNA) precursors in eukaryotes?

• RNA polymerase I
• RNA polymerase II
• RNA polymerase III
• RNA-dependent RNA polymerase

Correct Answer: RNA polymerase I

Q32. Which RNA polymerase transcribes tRNA and 5S rRNA in eukaryotes?

• RNA polymerase I
• RNA polymerase II
• RNA polymerase III
• Reverse transcriptase

Correct Answer: RNA polymerase III

Q33. Which mRNA features contribute most to stability in eukaryotic cytoplasm?

• Short 3′ UTR and lack of poly(A) tail
• 5′ cap and poly(A) tail
• Absence of splicing
• High GC content only

Correct Answer: 5′ cap and poly(A) tail

Q34. What structural element in nascent RNA can cause RNA polymerase to pause during elongation?

• Triple-helix DNA-RNA hybrids
• Stem-loop (hairpin) structures in the RNA
• 5′ cap formation
• Poly(A) tail synthesis

Correct Answer: Stem-loop (hairpin) structures in the RNA

Q35. In the lac operon of E. coli, what is the role of the lac repressor in the absence of lactose?

• It stimulates RNA polymerase binding to promoter
• It binds the operator and blocks transcription
• It cleaves lactose into glucose and galactose
• It methylates the promoter to activate transcription

Correct Answer: It binds the operator and blocks transcription

Q36. How does an inducer like allolactose affect the lac repressor?

• It degrades the repressor protein
• It binds to the repressor causing a conformational change and release from the operator
• It methylates the operator DNA
• It recruits RNase to degrade mRNA

Correct Answer: It binds to the repressor causing a conformational change and release from the operator

Q37. What regulatory mechanism reduces transcription of the trp operon in bacteria in response to high tryptophan levels?

• Attenuation via leader peptide and transcription termination
• DNA methylation of the trp promoter
• Splicing of the operon transcript
• Polyadenylation of trp mRNA

Correct Answer: Attenuation via leader peptide and transcription termination

Q38. Which statement best contrasts eukaryotic and prokaryotic promoters?

• Eukaryotic promoters typically have clear -10 and -35 elements like bacteria
• Prokaryotic promoters require nucleosomes to initiate transcription
• Eukaryotic promoters often rely on multiple core elements and chromatin context rather than a single conserved -10/-35 motif
• Only prokaryotes use TATA boxes

Correct Answer: Eukaryotic promoters often rely on multiple core elements and chromatin context rather than a single conserved -10/-35 motif

Q39. A point mutation in a promoter region that reduces binding affinity of RNA polymerase will most likely cause what effect?

• Increased translation efficiency
• Altered splicing of pre-mRNA
• Reduced transcription initiation and lower mRNA levels
• Immediate degradation of genomic DNA

Correct Answer: Reduced transcription initiation and lower mRNA levels

Q40. Which experimental technique is used to detect and size specific RNA molecules using a labeled probe?

• Northern blot
• Western blot
• Southern blot
• ELISA

Correct Answer: Northern blot

Q41. Which technique involves reverse transcription followed by PCR to detect specific mRNA expression?

• Chromatin immunoprecipitation (ChIP)
• RT-PCR (reverse transcription PCR)
• Mass spectrometry
• DNA microarray hybridization

Correct Answer: RT-PCR (reverse transcription PCR)

Q42. What does a run-off transcription assay measure?

• Protein-DNA binding affinity
• Transcriptional activity producing transcripts of defined lengths from linear templates
• RNA splicing efficiency in vivo
• Rate of translation of a reporter mRNA

Correct Answer: Transcriptional activity producing transcripts of defined lengths from linear templates

Q43. CpG islands are often associated with which class of promoters?

• Transient viral promoters only
• Housekeeping gene promoters
• Prokaryotic operon promoters
• Promoters that are always methylated and silent

Correct Answer: Housekeeping gene promoters

Q44. Which statement correctly describes introns?

• Introns are coding sequences retained in mature mRNA
• Introns are non-coding sequences removed from pre-mRNA by splicing
• Introns are the 5′ cap structures
• Introns are the poly(A) tails added to mRNA

Correct Answer: Introns are non-coding sequences removed from pre-mRNA by splicing

Q45. Which snRNA recognizes the 5′ splice site during spliceosome assembly?

• U2 snRNA
• U1 snRNA
• U6 snRNA
• U5 snRNA

Correct Answer: U1 snRNA

Q46. Polyadenylation of eukaryotic mRNA occurs:

• On the 5′ end immediately after initiation
• After cleavage at the poly(A) site on the 3′ end
• Only in the cytoplasm during translation
• Within introns during splicing

Correct Answer: After cleavage at the poly(A) site on the 3′ end

Q47. How can enhancers act over large genomic distances to regulate transcription?

• By linear sliding of transcription factors along DNA only
• By looping the DNA to bring enhancers into proximity with promoters
• By being transcribed into microRNAs that activate promoters
• By converting to promoters themselves

Correct Answer: By looping the DNA to bring enhancers into proximity with promoters

Q48. RNA editing can alter nucleotide identity post-transcriptionally. Which example is a common type of RNA editing?

• U-to-A conversion by ribosomes
• A-to-I editing by ADAR enzymes (A->I interpreted as G)
• C-to-T editing in the DNA
• Poly(A) trimming by deadenylases

Correct Answer: A-to-I editing by ADAR enzymes (A->I interpreted as G)

Q49. What is the consequence of RNA polymerase backtracking during elongation?

• Immediate termination of transcription via rho factor
• Transcriptional arrest that often requires cleavage of nascent RNA to resume elongation
• Splicing of the nascent transcript while still attached
• Conversion of mRNA into tRNA

Correct Answer: Transcriptional arrest that often requires cleavage of nascent RNA to resume elongation

Q50. Which high-throughput method provides a genome-wide view of transcript abundance and splice variants?

• Chromatin immunoprecipitation sequencing (ChIP-seq)
• RNA sequencing (RNA-seq)
• Southern blotting
• Two-dimensional gel electrophoresis

Correct Answer: RNA sequencing (RNA-seq)

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

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