Protein synthesis MCQs With Answer

Protein synthesis MCQs With Answer for B. Pharm students provides a concise, exam-focused review of transcription, translation, ribosome structure, and regulation of gene expression. This set covers core concepts such as mRNA processing, tRNA charging, initiation/elongation/termination factors, codon-anticodon pairing, wobble, and post-translational modification with clinical relevance to antibiotics and pharmacological inhibitors. Designed for B. Pharm exam prep and competitive tests, these targeted protein synthesis MCQs emphasize mechanism, prokaryotic versus eukaryotic differences, and drug targets to strengthen both conceptual understanding and application in pharmacy practice. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which enzyme catalyzes peptide bond formation during translation?

• Peptidyl transferase activity of the ribosomal RNA
• Aminoacyl-tRNA synthetase
• Release factor
• RNA polymerase

Correct Answer: Peptidyl transferase activity of the ribosomal RNA

Q2. In prokaryotic translation initiation, the Shine-Dalgarno sequence pairs with which ribosomal component?

• 16S rRNA of the 30S subunit
• 23S rRNA of the 50S subunit
• 5S rRNA
• Initiation factor IF-2

Correct Answer: 16S rRNA of the 30S subunit

Q3. Which molecule directly delivers amino acids to the ribosome?

• tRNA
• mRNA
• rRNA
• DNA

Correct Answer: tRNA

Q4. Which antibiotic binds to the 30S ribosomal subunit and causes misreading of mRNA?

• Aminoglycosides (e.g., gentamicin)
• Chloramphenicol
• Macrolides (e.g., erythromycin)
• Tetracyclines

Correct Answer: Aminoglycosides (e.g., gentamicin)

Q5. Wobble at the third codon position allows which of the following?

• One tRNA to recognize multiple codons
• Precise codon-anticodon pairing at all three bases
• Ribosome binding to mRNA cap
• Termination of translation

Correct Answer: One tRNA to recognize multiple codons

Q6. Which factor is required for eukaryotic translation initiation but not for prokaryotic initiation?

• eIF4E (cap-binding protein)
• IF-1
• IF-2
• Shine-Dalgarno binding

Correct Answer: eIF4E (cap-binding protein)

Q7. Aminoacyl-tRNA synthetases are responsible for which step?

• Charging tRNA with the correct amino acid
• Peptide bond formation
• mRNA transcription
• Ribosome assembly

Correct Answer: Charging tRNA with the correct amino acid

Q8. During translation elongation, GTP hydrolysis is directly required for which process?

• Translocation of the ribosome along mRNA
• Formation of the peptide bond
• tRNA charging
• mRNA splicing

Correct Answer: Translocation of the ribosome along mRNA

Q9. Which of the following is a eukaryotic-specific ribosomal inhibitor used in research that blocks translocation?

• Cycloheximide
• Tetracycline
• Chloramphenicol
• Streptomycin

Correct Answer: Cycloheximide

Q10. The start codon in most mRNAs codes for which amino acid in eukaryotes?

• Methionine
• N-formylmethionine
• Tryptophan
• Leucine

Correct Answer: Methionine

Q11. Which RNA modification is essential for prokaryotic initiation and involves the first methionine?

• N-formylation of initiator tRNA (fMet)
• 5′ capping
• Polyadenylation
• Splicing

Correct Answer: N-formylation of initiator tRNA (fMet)

Q12. Which process removes introns from pre-mRNA before translation in eukaryotes?

• Splicing by the spliceosome
• Polyadenylation
• Transcription termination
• Ribosomal assembly

Correct Answer: Splicing by the spliceosome

Q13. How does tetracycline inhibit protein synthesis?

• Blocks tRNA binding to the A site of the 30S subunit
• Inhibits peptidyl transferase at 50S
• Blocks translocation at the 60S subunit
• Inhibits aminoacyl-tRNA synthetase

Correct Answer: Blocks tRNA binding to the A site of the 30S subunit

Q14. Which component serves as the catalytic center for peptide bond formation?

• 23S rRNA in 50S ribosomal subunit
• Protein L7/L12
• Aminoacyl-tRNA synthetase
• mRNA

Correct Answer: 23S rRNA in 50S ribosomal subunit

Q15. Puromycin causes premature termination by mimicking which molecule?

• Aminoacyl-tRNA
• mRNA codon
• Release factor
• Peptidyl transferase

Correct Answer: Aminoacyl-tRNA

Q16. Which post-translational modification commonly targets proteins for proteasomal degradation?

• Ubiquitination
• Phosphorylation
• Glycosylation
• Methylation

Correct Answer: Ubiquitination

Q17. The genetic code is described as degenerate. What does this mean?

• Multiple codons encode the same amino acid
• Codons change during protein synthesis
• Each codon encodes multiple amino acids
• There are only 20 codons

Correct Answer: Multiple codons encode the same amino acid

Q18. Which factor recognizes stop codons and promotes polypeptide release in prokaryotes?

• Release factors RF1 and RF2
• RF3 alone
• EF-Tu
• RRF (ribosome recycling factor)

Correct Answer: Release factors RF1 and RF2

Q19. What role does chaperone protein GroEL/GroES play in protein synthesis?

• Assists in protein folding post-translation
• Charges tRNAs with amino acids
• Facilitates ribosome assembly
• Removes signal peptides

Correct Answer: Assists in protein folding post-translation

Q20. Which mechanism decreases translation of mRNA in eukaryotes by binding to the 3′ UTR?

• miRNA-mediated translational repression
• Alternative splicing
• Cap-dependent initiation
• RNA polymerase pausing

Correct Answer: miRNA-mediated translational repression

Q21. Which technique measures newly synthesized proteins in cells using labeled amino acids?

• Pulse-chase labeling
• Western blotting without labels
• ELISA
• PCR amplification

Correct Answer: Pulse-chase labeling

Q22. Which sequence signals cotranslational targeting of secretory proteins to the ER?

• Signal peptide at the N-terminus
• Polyadenylation signal
• Start codon context alone
• Internal ribosome entry site (IRES)

Correct Answer: Signal peptide at the N-terminus

Q23. Which of the following is NOT a function of rRNA?

• Carrying amino acids to ribosome
• Forming the peptidyl transferase center
• Maintaining ribosome structure
• Facilitating mRNA-tRNA interactions

Correct Answer: Carrying amino acids to ribosome

Q24. A nonsense mutation results in which change to the protein?

• Premature stop codon leading to truncated protein
• Amino acid substitution with similar properties
• Insertion of extra amino acids without stop
• No change due to silent mutation

Correct Answer: Premature stop codon leading to truncated protein

Q25. Which cellular organelle is the primary site of translation in eukaryotic cells?

• Cytosolic ribosomes and rough endoplasmic reticulum
• Golgi apparatus
• Mitochondria only
• Nucleus

Correct Answer: Cytosolic ribosomes and rough endoplasmic reticulum

Q26. Which antibiotic inhibits the 50S peptidyl transferase and can cause aplastic anemia as an adverse effect?

• Chloramphenicol
• Tetracycline
• Aminoglycoside
• Macrolide

Correct Answer: Chloramphenicol

Q27. What is the role of EF-Tu in prokaryotic translation?

• Delivers aminoacyl-tRNA to the A site in a GTP-dependent manner
• Forms peptide bonds directly
• Releases completed polypeptides
• Initiates ribosomal assembly

Correct Answer: Delivers aminoacyl-tRNA to the A site in a GTP-dependent manner

Q28. How does macrolide antibiotic inhibit bacterial protein synthesis?

• Blocks exit tunnel of 50S ribosome, inhibiting elongation
• Prevents tRNA charging
• Binds to 30S and causes misreading
• Inhibits mRNA synthesis

Correct Answer: Blocks exit tunnel of 50S ribosome, inhibiting elongation

Q29. Which element in eukaryotic mRNA enhances translation initiation by recruiting ribosomes?

• 5′ cap (7-methylguanosine)
• Poly-A tail alone
• Signal peptide
• Shine-Dalgarno sequence

Correct Answer: 5′ cap (7-methylguanosine)

Q30. Frameshift mutations most commonly result from which type of genetic change?

• Insertion or deletion not in multiples of three nucleotides
• A single base substitution that is silent
• In-frame insertion of three nucleotides
• Synonymous codon change

Correct Answer: Insertion or deletion not in multiples of three nucleotides

Q31. Which of the following is true about polysomes (polyribosomes)?

• Multiple ribosomes translate a single mRNA simultaneously
• They are involved in DNA replication
• They are only found in prokaryotes
• Each ribosome translates a different mRNA exclusively

Correct Answer: Multiple ribosomes translate a single mRNA simultaneously

Q32. Which feature distinguishes mitochondrial protein synthesis from cytosolic protein synthesis?

• Mitochondria use a slightly different genetic code and ribosomes
• Mitochondria do not use tRNA
• Mitochondria lack translation machinery entirely
• Mitochondrial mRNAs are capped and polyadenylated like eukaryotic nuclear mRNA

Correct Answer: Mitochondria use a slightly different genetic code and ribosomes

Q33. Which process immediately follows translation for many secreted proteins?

• Signal peptide cleavage and translocation into ER lumen
• DNA replication
• mRNA splicing
• Ribosome disassembly in nucleus

Correct Answer: Signal peptide cleavage and translocation into ER lumen

Q34. Which factor catalyzes the recycling of ribosomal subunits after termination in bacteria?

• Ribosome recycling factor (RRF) with EF-G
• Release factor RF3 alone
• IF-1 and IF-3 only
• Peptidyl transferase

Correct Answer: Ribosome recycling factor (RRF) with EF-G

Q35. Which codon is the universal stop codon in most genetic codes?

• UAA, UAG, and UGA are stop codons
• AUG is a stop codon
• UUU is a stop codon
• GUG is a stop codon

Correct Answer: UAA, UAG, and UGA are stop codons

Q36. How does nonsense-mediated decay (NMD) affect mRNA?

• Degrades mRNA containing premature termination codons
• Enhances translation of faulty mRNA
• Removes methyl groups from ribose
• Facilitates alternative splicing

Correct Answer: Degrades mRNA containing premature termination codons

Q37. Which amino acid is specified by the codon UGG?

• Tryptophan
• Phenylalanine
• Methionine
• Stop

Correct Answer: Tryptophan

Q38. Which experimental method separates ribosomal subunits and polysomes based on size and density?

• Sucrose density gradient centrifugation
• Gel electrophoresis of DNA
• ELISA
• Mass spectrometry of lipids

Correct Answer: Sucrose density gradient centrifugation

Q39. Which of the following modifications occurs to eukaryotic pre-mRNA and enhances stability and translation?

• 5′ capping and 3′ polyadenylation
• N-formylation of methionine
• Addition of Shine-Dalgarno sequence
• Ribosome methylation

Correct Answer: 5′ capping and 3′ polyadenylation

Q40. What is codon bias and why is it pharmacologically relevant?

• Preferential use of certain synonymous codons affecting expression and heterologous protein production
• Mutation of codons into stop codons randomly
• Uniform usage of all codons in all organisms
• Loss of wobble pairing in tRNA

Correct Answer: Preferential use of certain synonymous codons affecting expression and heterologous protein production

Q41. Which protein complex degrades misfolded proteins in eukaryotic cells?

• Proteasome (26S)
• Ribosome
• Signal recognition particle (SRP)
• Chaperonin GroEL alone

Correct Answer: Proteasome (26S)

Q42. Which of the following is true about translation termination?

• Release factors recognize stop codons and catalyze release of the polypeptide
• tRNA enters the A site to recognize stop codons
• Peptidyl transferase continues elongation past stop codon
• Initiation factors mediate termination

Correct Answer: Release factors recognize stop codons and catalyze release of the polypeptide

Q43. Which molecule is often required to fold nascent polypeptides as they emerge from the ribosome?

• Molecular chaperones like Hsp70
• tRNA synthetases
• RNA polymerase II
• DNA ligase

Correct Answer: Molecular chaperones like Hsp70

Q44. Which drug class targets bacterial protein synthesis but is bacteriostatic rather than bactericidal in many cases?

• Macrolides
• Aminoglycosides
• Fluoroquinolones
• Beta-lactams

Correct Answer: Macrolides

Q45. What is the primary function of the signal recognition particle (SRP)?

• Directs nascent polypeptides to the endoplasmic reticulum
• Removes signal peptides enzymatically
• Translates mitochondrial proteins
• Charges tRNAs

Correct Answer: Directs nascent polypeptides to the endoplasmic reticulum

Q46. Which of the following is a direct consequence of a mutation in a tRNA synthetase gene?

• Misincorporation of amino acids into proteins
• Immediate degradation of all mRNA
• Loss of ribosomal RNA synthesis
• Enhanced fidelity of translation

Correct Answer: Misincorporation of amino acids into proteins

Q47. In bacterial operons, how does attenuation regulate protein synthesis?

• Transcription termination is influenced by translation of a leader peptide
• By modifying tRNA charging rates only
• Through cap-dependent translation initiation
• By ubiquitination of RNA polymerase

Correct Answer: Transcription termination is influenced by translation of a leader peptide

Q48. Which chemical modification on rRNA can contribute to antibiotic resistance?

• Methylation of rRNA nucleotides
• Phosphorylation of mRNA cap
• Glycosylation of tRNA
• Deamination of DNA

Correct Answer: Methylation of rRNA nucleotides

Q49. Which factor is essential for charging tRNAs with amino acids and has proofreading activity?

• Aminoacyl-tRNA synthetase
• Peptidyl transferase
• EF-G
• Release factor RF1

Correct Answer: Aminoacyl-tRNA synthetase

Q50. Which experimental inhibitor is commonly used to study translation by mimicking aminoacyl-tRNA and causing chain termination?

• Puromycin
• Tetracycline
• Cycloheximide
• Chloramphenicol

Correct Answer: Puromycin

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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