Translation process MCQs With Answer

Introduction: The translation process is a central topic in molecular pharmacology and protein biosynthesis for B. Pharm students. This overview explains how mRNA codons are decoded by tRNA and ribosomes to synthesize proteins, highlighting key terms: translation, protein synthesis, ribosome, initiation, elongation, termination, aminoacyl‑tRNA synthetase, start codon, Shine‑Dalgarno, Kozak sequence, and antibiotics that target translation. Understanding mechanistic details—GTP‑dependent factors, peptidyl transferase activity, post‑translational modifications, signal peptides, and quality control systems—links molecular events to drug action and toxicity. Solid grasp of these concepts supports rational drug design and therapeutic interventions. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which codon most commonly serves as the start codon for translation in both prokaryotes and eukaryotes?

• AUG (methionine)
• UAG (stop)
• UGA (stop)
• GUG (valine)

Correct Answer: AUG (methionine)

Q2. Which ribosomal composition is typical of eukaryotic cytosolic ribosomes?

• 70S, composed of 50S and 30S
• 80S, composed of 60S and 40S
• 70S, composed of 60S and 40S
• 80S, composed of 50S and 30S

Correct Answer: 80S, composed of 60S and 40S

Q3. What is the primary function of aminoacyl‑tRNA synthetases in translation?

• Translocate the ribosome along mRNA
• Charge tRNAs with their cognate amino acids
• Recognize start codons during initiation
• Catalyze peptide bond formation

Correct Answer: Charge tRNAs with their cognate amino acids

Q4. Which sequence element in prokaryotic mRNA helps recruit the ribosome during initiation?

• Kozak consensus sequence
• Poly(A) tail
• Shine‑Dalgarno sequence
• Internal ribosome entry site (IRES)

Correct Answer: Shine‑Dalgarno sequence

Q5. Which component of the ribosome has peptidyl transferase enzymatic activity?

• Ribosomal proteins of the small subunit
• rRNA of the large subunit
• mRNA bound to the ribosome
• tRNA anticodon loop

Correct Answer: rRNA of the large subunit

Q6. The wobble hypothesis explains variability in which position of the codon‑anticodon pairing?

• First (5′) base of the codon
• Second base of the codon
• Third (3′) base of the codon
• Entire codon equally

Correct Answer: Third (3′) base of the codon

Q7. In prokaryotic elongation, which factor delivers aminoacyl‑tRNA to the A site in a GTP‑dependent manner?

• EF‑G
• EF‑Tu
• IF‑2
• RF‑1

Correct Answer: EF‑Tu

Q8. What is the role of EF‑G (or eEF2) during translation?

• Initiation complex assembly
• Charging tRNA with amino acids
• Translocation of peptidyl‑tRNA and mRNA through the ribosome
• Termination by recognizing stop codons

Correct Answer: Translocation of peptidyl‑tRNA and mRNA through the ribosome

Q9. Which antibiotic acts by mimicking aminoacyl‑tRNA and causing premature chain termination?

• Tetracycline
• Puromycin
• Chloramphenicol
• Streptomycin

Correct Answer: Puromycin

Q10. Which release factor in eukaryotes recognizes all three stop codons to terminate translation?

• RF1
• RF2
• RF3
• eRF1

Correct Answer: eRF1

Q11. What term describes multiple ribosomes simultaneously translating a single mRNA molecule?

• Polysome (polyribosome)
• Monosome
• Ribosomal aggregate
• Translatosome

Correct Answer: Polysome (polyribosome)

Q12. Which post‑translational modification commonly occurs in the endoplasmic reticulum and Golgi apparatus?

• Ubiquitination
• Glycosylation
• Phosphorylation by cytosolic kinases
• Methylation of DNA

Correct Answer: Glycosylation

Q13. How does the signal recognition particle (SRP) participate in co‑translational targeting?

• It polyadenylates mRNA for stability
• It cleaves signal peptides from nascent chains
• It recognizes the signal peptide and pauses translation to direct the ribosome to the ER membrane
• It methylates tRNAs to improve decoding

Correct Answer: It recognizes the signal peptide and pauses translation to direct the ribosome to the ER membrane

Q14. Nonsense‑mediated mRNA decay (NMD) primarily targets mRNAs that contain what abnormality?

• Extended 3′ UTRs without stop codons
• Premature termination codons upstream of the last exon‑exon junction
• Excessive GC content in coding sequence
• Multiple Shine‑Dalgarno sequences

Correct Answer: Premature termination codons upstream of the last exon‑exon junction

Q15. A frameshift mutation in an open reading frame typically results in which outcome?

• Silent substitution with no amino acid change
• Altered reading frame leading to widespread missense and often premature stop codons
• Enhanced translation efficiency
• Replacement of a single amino acid only

Correct Answer: Altered reading frame leading to widespread missense and often premature stop codons

Q16. Why is GTP hydrolysis important during translation?

• It forms the peptide bond between amino acids
• It provides energy for conformational changes of translation factors and ribosome movements
• It charges tRNA with amino acids
• It unwinds mRNA secondary structure

Correct Answer: It provides energy for conformational changes of translation factors and ribosome movements

Q17. Which mechanism contributes most to the accuracy of amino acid incorporation during translation?

• Proofreading by the ribosome after peptide bond formation
• Specificity of aminoacyl‑tRNA synthetases during tRNA charging
• Random selection of tRNA anticodons
• mRNA editing prior to translation

Correct Answer: Specificity of aminoacyl‑tRNA synthetases during tRNA charging

Q18. Removal of the initiator methionine from many nascent proteins is catalyzed by which enzyme?

• Methionine adenosyltransferase
• Methionine aminopeptidase
• Signal peptidase
• Formyltransferase

Correct Answer: Methionine aminopeptidase

Q19. Molecular chaperones such as Hsp70 assist in translation by what primary function?

• Facilitating ribosome assembly from subunits
• Guiding proper folding of nascent polypeptides and preventing aggregation
• Directly catalyzing peptide bond formation
• Recognizing stop codons during termination

Correct Answer: Guiding proper folding of nascent polypeptides and preventing aggregation

Q20. How does the ubiquitin‑proteasome system relate to protein translation quality control?

• It methylates nascent chains to promote folding
• It selectively tags and degrades misfolded or abnormal proteins after translation
• It initiates translation at IRES elements
• It enhances ribosomal translocation speed

Correct Answer: It selectively tags and degrades misfolded or abnormal proteins after translation

Q21. Which sequence surrounding the start codon in eukaryotic mRNA enhances initiation efficiency?

• Shine‑Dalgarno sequence
• Kozak consensus sequence
• Polyadenylation signal
• TATA box

Correct Answer: Kozak consensus sequence

Q22. Chloramphenicol inhibits bacterial translation by targeting which activity?

• Blocking A‑site tRNA entry
• Inhibiting peptidyl transferase activity of the 50S subunit
• Preventing initiation factor binding
• Interfering with translocation via EF‑G

Correct Answer: Inhibiting peptidyl transferase activity of the 50S subunit

Q23. Eukaryotic ribosome recruitment to mRNA commonly begins with recognition of which feature?

• 5′ cap structure by eIF4E followed by scanning to the start codon
• Shine‑Dalgarno sequence upstream of AUG
• Direct binding to poly(A) tail by the small subunit
• Immediate IRES binding in all mRNAs

Correct Answer: 5′ cap structure by eIF4E followed by scanning to the start codon

Q24. Internal ribosome entry sites (IRES) enable which type of translation initiation?

• Cap‑dependent scanning initiation
• Cap‑independent initiation at internal mRNA sites
• Translation exclusively in prokaryotes
• Initiation only after polyadenylation

Correct Answer: Cap‑independent initiation at internal mRNA sites

Q25. The aminoacylation reaction catalyzed by aminoacyl‑tRNA synthetases consumes which high‑energy molecule?

• GTP
• ATP
• UTP
• CTP

Correct Answer: ATP

Q26. Which statement best describes the genetic code as used in translation?

• Overlapping and ambiguous, with shared nucleotides among codons
• Non‑overlapping, commaless, and nearly universal
• Variable length codons from 2–4 bases depending on species
• Completely different between prokaryotes and eukaryotes

Correct Answer: Non‑overlapping, commaless, and nearly universal

Q27. A synonymous (silent) mutation in the coding sequence may still affect translation by which mechanism?

• Altering the encoded amino acid
• Changing mRNA secondary structure or codon usage affecting translation efficiency
• Introducing a premature stop codon
• Converting mRNA to rRNA

Correct Answer: Changing mRNA secondary structure or codon usage affecting translation efficiency

Q28. The Sec61 translocon complex is primarily involved in which process related to translation?

• Ribosome recycling after termination
• Co‑translational translocation of nascent peptides into/through the ER membrane
• Splicing of pre‑mRNA prior to export
• Polyadenylation of mRNA in the nucleus

Correct Answer: Co‑translational translocation of nascent peptides into/through the ER membrane

Q29. Ribosome recycling factor (RRF) in bacteria works with which factor to disassemble post‑termination complexes?

• RF1 alone
• EF‑Tu
• EF‑G and GTP
• IF‑3 only

Correct Answer: EF‑G and GTP

Q30. Macrolide antibiotics (e.g., erythromycin) inhibit bacterial translation by which primary mechanism?

• Blocking aminoacyl‑tRNA synthetases
• Inhibiting small subunit decoding function
• Obstructing the peptide exit tunnel of the 50S subunit, stalling elongation
• Promoting premature termination via release factor activation

Correct Answer: Obstructing the peptide exit tunnel of the 50S subunit, stalling elongation

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