MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 30 Mcqs, each offering curated multiple-choice questions to sharpen your Microbiology knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Which phage always carries a small piece of genome? |
| A. | Lambda |
| B. | Mu |
| C. | T4 |
| D. | T3 |
| Answer» C. T4 | |
| 2. |
What are the values for the subunits of the 70S ribosomes of E? |
| A. | 40S and 30S |
| B. | 50S and 20S |
| C. | 50S and 30S |
| D. | 40S and 20S |
| Answer» D. 40S and 20S | |
| 3. |
Which binding is inhibited by pactamycin? |
| A. | Aminoacyl-tRNA to the A-site of 30S subunit |
| B. | Initiator-tRNA to 30S/40S initiation complexes |
| C. | Peptidyl t-RNA to the 50S subunit |
| D. | Formation of peptide bond in P site |
| Answer» C. Peptidyl t-RNA to the 50S subunit | |
| 4. |
Which of the following act as the blueprint or template for the process of protein synthesis that takes place on ribosomes? |
| A. | rRNA |
| B. | DNA |
| C. | tRNA |
| D. | mRNA |
| Answer» E. | |
| 5. |
Negative regulation of protein synthesis is accomplished by |
| A. | allosteric inhibition |
| B. | the binding of RNA polymerase to the promoter |
| C. | the binding of a repressor to the DNA |
| D. | the binding of a repressor to the RNA polymerase |
| Answer» D. the binding of a repressor to the RNA polymerase | |
| 6. |
The development of global regulatory systems in prokaryotes |
| A. | determines the exact location of the cell on the globe |
| B. | aids in DNA replication |
| C. | determines the exact location of the replication site |
| D. | regulates many genes under varying environmental conditions |
| Answer» E. | |
| 7. |
What is the direct cause of cell death by diphtheria toxin? |
| A. | Formation of an ion channel in the cell membrane |
| B. | Inactivation of a translational elongation factor |
| C. | Induction of apoptosis |
| D. | None of the above |
| Answer» C. Induction of apoptosis | |
| 8. |
The interaction between the mRNA and tRNA determined the position of amino acid in a polypeptide sequence. This is called the |
| A. | stagerivity |
| B. | Wobble hypothesis |
| C. | promiscuity |
| D. | adaptor hypothesis |
| Answer» E. | |
| 9. |
What are the Svedberg values for the subunits of the 70S ribosomes of E. colli? |
| A. | 40S and 30S |
| B. | 50S and 20S |
| C. | 50S and 30S |
| D. | 40S and 20S |
| Answer» D. 40S and 20S | |
| 10. |
Which of the following three codons translate as serine (Ser)? |
| A. | AGU |
| B. | CGA |
| C. | CAU |
| D. | AUG |
| Answer» B. CGA | |
| 11. |
Which of the following is a nontranslated sequence located between the transcription and the translation start site? |
| A. | Ending frame |
| B. | Leader sequence |
| C. | Trailer sequence |
| D. | Reading frame |
| Answer» C. Trailer sequence | |
| 12. |
The final step of gene expression is protein synthesis, which is also known as |
| A. | replication |
| B. | translation |
| C. | transcription |
| D. | none of these |
| Answer» C. transcription | |
| 13. |
What is the maximum number of different amino acids in a polypeptide chain coded by the synthetic polyribonucleotides (UCAG)5? |
| A. | One |
| B. | Two |
| C. | Three |
| D. | Four |
| Answer» D. Four | |
| 14. |
The ribosome binding site |
| A. | forms a stem-loop structure in the RNA |
| B. | is located upstream of the promoter sequence |
| C. | is located immediately upstream of the start codon |
| D. | is more likely to be associated with an operon than with a gene encoding a single protein |
| Answer» D. is more likely to be associated with an operon than with a gene encoding a single protein | |
| 15. |
Which of the following modified amino acid is used at the starting of most prokaryotic proteins? |
| A. | N-formylserine |
| B. | N-formylmethionine |
| C. | N-formylleucine |
| D. | N-formylalanine |
| Answer» C. N-formylleucine | |
| 16. |
The role of molecular chaperones is to |
| A. | facilitate binding of ribosomes to mRNA |
| B. | degrade newly synthesized polypeptides that contain inaccurate sequences |
| C. | facilitate binding of RNA polymerase to DNA |
| D. | aid a newly synthesized polypeptide in folding to its proper shape |
| Answer» E. | |
| 17. |
Which stop codon has been found to encode selenocysteine? |
| A. | UAA |
| B. | UAG |
| C. | UGA |
| D. | AGA |
| Answer» D. AGA | |
| 18. |
Three stop codons, which aids in termination of translation are also known as |
| A. | pause codons |
| B. | nonsense codons |
| C. | missense codons |
| D. | antisense codons |
| Answer» C. missense codons | |
| 19. |
A quorum sensing system |
| A. | detects a signal from the external environment |
| B. | senses a compound produced by the bacterium itself |
| C. | consists of a sensor component that phosphorylates a regulatory protein |
| D. | controls the activity of ribosomes directly |
| Answer» C. consists of a sensor component that phosphorylates a regulatory protein | |
| 20. |
The Shine-Dalgarno sequence is |
| A. | trailer sequence |
| B. | a stop codon |
| C. | the reading frame of a gene |
| D. | a short sequence that acts as a ribosomal binding site |
| Answer» E. | |
| 21. |
During amino acid activation a(n) |
| A. | amino acid is bound to tRNA |
| B. | amino acid is bound to mRNA |
| C. | methyl group is attached to rRNA |
| D. | methyl group is attached to an amino acid |
| Answer» B. amino acid is bound to mRNA | |
| 22. |
The nonsense codon(s) is/are |
| A. | UAG |
| B. | UAA |
| C. | UGA |
| D. | all of these |
| Answer» E. | |
| 23. |
Site in the ribosome from which the tRNA donates amino acids to the growing polypeptide chain is |
| A. | P site |
| B. | O site |
| C. | T site |
| D. | A site |
| Answer» B. O site | |
| 24. |
When was the genetic code completed? |
| A. | 1958 |
| B. | 1952 |
| C. | 1966 |
| D. | 1968 |
| Answer» D. 1968 | |
| 25. |
Which of the termination codon is called amber? |
| A. | UAA |
| B. | UAG |
| C. | UGA |
| D. | AUG |
| Answer» C. UGA | |
| 26. |
Which of the following molecule catalyzes the transpeptidation reaction? |
| A. | RNA polymerase |
| B. | Peptidyl transferase |
| C. | DNA ligase |
| D. | DNA polymerase |
| Answer» C. DNA ligase | |
| 27. |
What was the first bacterial genome to be sequenced and made public? |
| A. | <i>Bacillus subtilis</i> |
| B. | <i>Escherichia coli</i> |
| C. | <i>Haemophilus influenzae</i> |
| D. | No bacterial genome has been sequenced yet |
| Answer» D. No bacterial genome has been sequenced yet | |
| 28. |
What is the action of tetracycline in prokaryotes? |
| A. | It blocks translocation reaction on ribosomes |
| B. | It blocks peptidyl transferase reaction on ribosomes |
| C. | It blocks the binding of amino-acyl tRNA to the A site of ribosomes |
| D. | Not known with certainity |
| Answer» D. Not known with certainity | |
| 29. |
Which phage always carries a small piece of E.coli genome? |
| A. | Lambda |
| B. | Mu |
| C. | T4 |
| D. | T3 |
| Answer» C. T4 | |
| 30. |
Which of the following defines an open reading frame (ORF)? |
| A. | A sequence of genome in bacteriophage |
| B. | The sequence of a complete genome |
| C. | A plasmid vector used in genome sequencing |
| D. | A possible gene predicted by DNA sequencing |
| Answer» E. | |