Translation (Protein synthesis) MCQs With Answer

Translation (protein synthesis) MCQs With Answer

Translation is a vital topic for B. Pharm students, linking gene expression to pharmacology and drug action. This SEO-friendly, focused introduction and question set covers ribosome structure, mRNA decoding, tRNA charging, initiation/elongation/termination factors, codon recognition, wobble base pairing, post-translational modifications, and clinically relevant antibiotics that target translation. These targeted MCQs with answers deepen understanding of prokaryotic and eukaryotic differences, regulatory mechanisms, and therapeutic inhibition of protein synthesis. Answers emphasize mechanisms and clinical relevance to aid pharmacological application. ‘Now let’s test your knowledge with 50 MCQs on this topic.’

Q1. What is the primary outcome of the translation process?

• Synthesis of DNA from RNA
• Conversion of mRNA sequence into a polypeptide chain

Correct Answer: Conversion of mRNA sequence into a polypeptide chain

Q2. Where does translation primarily occur in prokaryotic cells?

• In the nucleus
• On the rough endoplasmic reticulum only
• In the cytoplasm on ribosomes
• Inside mitochondria exclusively

Correct Answer: In the cytoplasm on ribosomes

Q3. Which combination represents the prokaryotic ribosome subunits?

• 60S + 40S
• 50S + 30S
• 70S + 30S
• 80S total

Correct Answer: 50S + 30S

Q4. What is the composition of eukaryotic ribosomes?

• 70S composed of 50S and 20S
• 80S composed of 60S and 40S
• 55S composed of 35S and 20S
• 50S composed of 30S and 20S

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

Q5. The Shine-Dalgarno sequence in prokaryotic mRNA pairs with which ribosomal RNA?

• 23S rRNA
• 5S rRNA
• 16S rRNA
• 28S rRNA

Correct Answer: 16S rRNA

Q6. What sequence in eukaryotic mRNA helps position the ribosome at the start codon?

• Shine-Dalgarno sequence
• Kozak sequence
• TATA box
• Polyadenylation signal

Correct Answer: Kozak sequence

Q7. Which codon serves as the universal start codon for translation in most organisms?

• UAA
• AUG
• UGA
• UAG

Correct Answer: AUG

Q8. Which enzyme charges tRNA with its cognate amino acid?

• Peptidyl transferase
• Aminoacyl-tRNA synthetase
• RNA polymerase
• Ribosomal protein S1

Correct Answer: Aminoacyl-tRNA synthetase

Q9. Which nucleotide provides the direct energy source for elongation factor-mediated steps during translation?

• ATP
• CTP
• GTP
• UTP

Correct Answer: GTP

Q10. The peptidyl transferase activity that forms peptide bonds is carried out by:

• A protein enzyme in the small subunit
• Ribosomal RNA of the large subunit
• tRNA synthetase
• Elongation factor EF-Tu

Correct Answer: Ribosomal RNA of the large subunit

Q11. The “wobble” position in a codon refers to which nucleotide position?

• First nucleotide
• Second nucleotide
• Third nucleotide
• Position between codons

Correct Answer: Third nucleotide

Q12. A nonsense mutation results in which of the following changes?

• Substitution of one amino acid for another
• Insertion of an extra codon
• Introduction of a premature stop codon
• Duplication of a gene segment

Correct Answer: Introduction of a premature stop codon

Q13. A frameshift mutation is most commonly caused by:

• A point mutation replacing one base
• Insertion or deletion not in multiples of three nucleotides
• Silent mutation in third codon position
• Loss of a promoter region

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

Q14. What is a polysome (polyribosome)?

• A ribosome bound to the nucleus
• A single ribosome translating multiple mRNAs
• Multiple ribosomes translating the same mRNA simultaneously
• A ribosome lacking rRNA

Correct Answer: Multiple ribosomes translating the same mRNA simultaneously

Q15. In prokaryotic elongation, which factor delivers aminoacyl-tRNA to the A site?

• EF-G
• EF-Tu
• IF-3
• RF-1

Correct Answer: EF-Tu

Q16. Termination of translation occurs when a stop codon is recognized by:

• A tRNA carrying a stop amino acid
• Release factors (RFs)
• Peptidyl transferase only
• Initiation factors

Correct Answer: Release factors (RFs)

Q17. Which antibiotic inhibits the peptidyl transferase activity of the bacterial 50S subunit?

• Tetracycline
• Chloramphenicol
• Streptomycin
• Neomycin

Correct Answer: Chloramphenicol

Q18. Tetracycline primarily inhibits bacterial protein synthesis by:

• Blocking peptide bond formation
• Inhibiting aminoacyl-tRNA synthetase
• Preventing aminoacyl-tRNA from binding to the A site
• Degrading mRNA

Correct Answer: Preventing aminoacyl-tRNA from binding to the A site

Q19. Aminoglycoside antibiotics such as streptomycin cause bacterial cell death mainly by:

• Inhibiting peptidyl transferase center of 50S
• Causing misreading of mRNA and faulty proteins
• Inhibiting RNA polymerase
• Blocking the ribosomal exit tunnel

Correct Answer: Causing misreading of mRNA and faulty proteins

Q20. Macrolide antibiotics (e.g., erythromycin) inhibit protein synthesis by:

• Binding the 30S subunit to block tRNA charging
• Binding the 50S subunit and blocking the peptide exit tunnel/translocation
• Cleaving mRNA
• Preventing ribosome assembly in the nucleus

Correct Answer: Binding the 50S subunit and blocking the peptide exit tunnel/translocation

Q21. Incorporation of selenocysteine into a growing polypeptide requires which element in mRNA?

• Shine-Dalgarno sequence
• Poly-A tail
• SECIS (selenocysteine insertion sequence)
• Kozak sequence

Correct Answer: SECIS (selenocysteine insertion sequence)

Q22. Which particle recognizes and binds the signal peptide on nascent polypeptides destined for secretion?

• Signal peptidase
• SRP (signal recognition particle)
• Ubiquitin ligase
• Ribosomal protein L7/L12

Correct Answer: SRP (signal recognition particle)

Q23. Which protein family is primarily responsible for assisting newly synthesized proteins to fold correctly?

• Proteasomes
• Chaperones (e.g., Hsp70)
• Ribosomal proteins
• Translation initiation factors

Correct Answer: Chaperones (e.g., Hsp70)

Q24. Proteins targeted for degradation by the ubiquitin–proteasome system are tagged with:

• Phosphate groups
• Ubiquitin molecules
• Signal peptides
• Glycosylation

Correct Answer: Ubiquitin molecules

Q25. How many different aminoacyl-tRNA synthetases are there typically for accurate translation?

• One for all amino acids
• Twenty, one for each amino acid
• Forty, two per amino acid
• Ten, shared between similar amino acids

Correct Answer: Twenty, one for each amino acid

Q26. Which of the following are stop codons in the standard genetic code?

• AUG, GUG, UUG
• UAA, UAG, UGA
• AAA, AAG, AAC
• CCA, CCU, CCG

Correct Answer: UAA, UAG, UGA

Q27. Which statement correctly contrasts prokaryotic and eukaryotic mRNA translation?

• Prokaryotic mRNAs are monocistronic, eukaryotic are polycistronic
• Eukaryotic translation initiates at Shine-Dalgarno sequences
• Eukaryotic mRNAs are usually monocistronic while prokaryotic mRNAs can be polycistronic
• Translation in eukaryotes occurs in the cytoplasm and nucleus simultaneously

Correct Answer: Eukaryotic mRNAs are usually monocistronic while prokaryotic mRNAs can be polycistronic

Q28. An internal ribosome entry site (IRES) allows:

• Cap-dependent initiation only
• Ribosome entry independent of the 5′ cap structure
• Termination of translation
• Exclusive translation in mitochondria

Correct Answer: Ribosome entry independent of the 5′ cap structure

Q29. The 5′ cap structure of eukaryotic mRNA is:

• A poly-A tail
• 7-methylguanosine (m7G) linked via a 5′-5′ triphosphate bond
• A triphosphate at the 3′ end
• A Shine-Dalgarno-like sequence

Correct Answer: 7-methylguanosine (m7G) linked via a 5′-5′ triphosphate bond

Q30. The ‘reading frame’ of an mRNA refers to:

• The orientation of the ribosome subunits
• Grouping of nucleotides into consecutive non-overlapping triplets from a start codon
• The sequence of tRNA molecules only
• The 3D conformation of the nascent peptide

Correct Answer: Grouping of nucleotides into consecutive non-overlapping triplets from a start codon

Q31. Which tRNA carries the initiator amino acid to the P site in bacteria?

• tRNAi^Met (eukaryotic initiator)
• tRNA^Leu
• fMet-tRNA^fMet (formylmethionyl-tRNA)
• tRNA^Met (uncharged)

Correct Answer: fMet-tRNA^fMet (formylmethionyl-tRNA)

Q32. The eukaryotic initiator tRNA differs from the bacterial initiator tRNA because it:

• Is formylated
• Is charged with fMet
• Is Met-tRNAi and is not formylated
• Does not bind the P site

Correct Answer: Is Met-tRNAi and is not formylated

Q33. Peptide bond formation connects the amino acid of the A-site tRNA to which group on the P-site tRNA?

• Its amino group
• Its hydroxyl group
• Its carboxyl group
• Its phosphate group

Correct Answer: Its carboxyl group

Q34. Which elongation factor catalyzes translocation of the ribosome along mRNA in bacteria?

• EF-Tu
• EF-G
• IF-2
• RF-3

Correct Answer: EF-G

Q35. The Kozak consensus sequence is important because it:

• Signals transcription termination
• Enhances recognition of the start codon in eukaryotic mRNAs
• Is required for ribosome binding in bacteria
• Marks mRNAs for degradation

Correct Answer: Enhances recognition of the start codon in eukaryotic mRNAs

Q36. Proteins that are synthesized on the rough endoplasmic reticulum are typically destined for:

• The cytosol only
• Secretion, membrane insertion, or lysosomal targeting
• Mitochondrial matrix exclusively
• Nuclear import only

Correct Answer: Secretion, membrane insertion, or lysosomal targeting

Q37. Which statement about mitochondrial translation in mammalian cells is correct?

• Mitochondria use 80S ribosomes identical to cytosolic ribosomes
• Mitochondrial translation resembles prokaryotic translation and uses 55S mitoribosomes
• Mitochondrial proteins are synthesized in the nucleus
• Mitochondria do not have their own tRNAs

Correct Answer: Mitochondrial translation resembles prokaryotic translation and uses 55S mitoribosomes

Q38. Nonsense-mediated mRNA decay (NMD) primarily serves to:

• Enhance translation of long mRNAs
• Degrade mRNAs containing premature stop codons
• Promote ribosome stalling at the start codon
• Polyadenylate mRNA ends

Correct Answer: Degrade mRNAs containing premature stop codons

Q39. The ribosome is considered a ribozyme because:

• It is made solely of proteins
• Its catalytic activity is performed by rRNA
• It synthesizes RNA from DNA
• It binds antibiotics

Correct Answer: Its catalytic activity is performed by rRNA

Q40. During elongation, the A site of the ribosome is occupied by:

• Peptidyl-tRNA carrying the growing chain
• Empty tRNA binding site only
• Aminoacyl-tRNA carrying the next amino acid
• Release factor recognizing a stop codon

Correct Answer: Aminoacyl-tRNA carrying the next amino acid

Q41. Addition of a phosphate group to a protein is called:

• Glycosylation
• Ubiquitination
• Phosphorylation
• Acetylation

Correct Answer: Phosphorylation

Q42. Enzyme responsible for cleaving signal peptides from nascent proteins in the ER is:

• Signal peptidase
• Proteasome
• Ribosomal peptidase L27
• Endonuclease G

Correct Answer: Signal peptidase

Q43. Charging of tRNA by aminoacyl-tRNA synthetase requires which high-energy molecule?

• GTP
• ATP
• CTP
• NADH

Correct Answer: ATP

Q44. Codon degeneracy refers to the fact that:

• Each codon codes for multiple amino acids
• Multiple codons can specify the same amino acid
• Each tRNA recognizes only one codon always
• Codons are variable in length

Correct Answer: Multiple codons can specify the same amino acid

Q45. Formation of polysomes on an mRNA generally results in:

• Decreased protein synthesis rate
• Increased translation efficiency and protein output
• Immediate mRNA degradation
• Blockade of initiation events

Correct Answer: Increased translation efficiency and protein output

Q46. A missense mutation causes which molecular change?

• A codon is changed to a stop codon
• A base change results in a different amino acid being incorporated
• Insertion of nucleotides causing frameshift
• Removal of the start codon only

Correct Answer: A base change results in a different amino acid being incorporated

Q47. The poly-A tail of eukaryotic mRNA primarily contributes to:

• Initiation complex assembly and mRNA stability
• Ribosome binding in prokaryotes
• Transport of mRNA into mitochondria
• Translation termination

Correct Answer: Initiation complex assembly and mRNA stability

Q48. Which eukaryotic initiation factor delivers Met-tRNAi to the 40S ribosomal subunit in a GTP-dependent manner?

• eIF4E
• eIF2
• eIF1
• eIF3

Correct Answer: eIF2

Q49. Linezolid, an oxazolidinone antibiotic, inhibits bacterial protein synthesis by:

• Inhibiting aminoacyl-tRNA synthetase
• Binding the 50S subunit and preventing formation of the initiation complex
• Blocking the A-site on the 30S subunit
• Cleaving mRNA at the start codon

Correct Answer: Binding the 50S subunit and preventing formation of the initiation complex

Q50. Which statement best explains why rRNA is central to ribosome function?

• rRNA stores genetic information for proteins
• rRNA provides the structural scaffold and catalytic activity for peptide bond formation
• rRNA recruits ubiquitin to nascent peptides
• rRNA is translated into ribosomal proteins

Correct Answer: rRNA provides the structural scaffold and catalytic activity for peptide bond formation

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.

Mail- Sachin@pharmacyfreak.com