MCQOPTIONS
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MCQOPTIONS
This section includes 38 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Which of the following inhibits initiation at higher concentrations? |
| A. | Chloramphenicol |
| B. | Streptomycin |
| C. | Diphtheria toxin |
| D. | Ricin |
| Answer» C. Diphtheria toxin | |
| 2. |
Which of the following catalyzes ADP-ribosylation of a diphthamide residue? |
| A. | Chloramphenicol |
| B. | Cycloheximide |
| C. | Diphtheria toxin |
| D. | Ricin |
| Answer» D. Ricin | |
| 3. |
The eukaryotic mRNA binding to the ribosomes is facilitated by ____________ |
| A. | T-RNA |
| B. | Poly-A tail |
| C. | Shine Dalgarno sequence |
| D. | 7-methyl guanosine cap |
| Answer» E. | |
| 4. |
What is the role of small nuclear RNAs in protein synthesis? |
| A. | It translates genetic code to a specific amino acid |
| B. | It modifies mRNA molecules prior to protein synthesis |
| C. | It provides a genetic blueprint for the protein |
| D. | It catalyzes the process |
| Answer» C. It provides a genetic blueprint for the protein | |
| 5. |
What is the role of mRNA in protein synthesis? |
| A. | It translates genetic code to a specific amino acid |
| B. | It modifies mRNA molecules prior to protein synthesis |
| C. | It provides a genetic blueprint for the protein |
| D. | It catalyzes the process |
| Answer» D. It catalyzes the process | |
| 6. |
Bacteria have ____________ |
| A. | 70S ribosomes |
| B. | 60S ribosomes |
| C. | 50S ribosomes |
| D. | 80S ribosomes |
| Answer» B. 60S ribosomes | |
| 7. |
Proteins contain __________ different amino acids, whereas DNA and RNA are composed of __________ different nucleotides |
| A. | 20,64 |
| B. | 3,20 |
| C. | 4,20 |
| D. | 20,4 |
| Answer» E. | |
| 8. |
Protein synthesis rates in prokaryotes are limited by the rate of mRNA synthesis. If RNA synthesis occurs at the rate of 50 nucleotides/sec, then rate of protein synthesis occurs at |
| A. | 10 amino acids/sec |
| B. | 17 amino acids/sec |
| C. | 25 amino acids/sec |
| D. | 50 amino acids/sec |
| Answer» C. 25 amino acids/sec | |
| 9. |
The lac operon contains the z, y and a structural genes |
| A. | encoding p-galactosidase, galactose permeases and thio-galactosidase transacetylase respectively |
| B. | encoding p-galactosidase and galactose permeases |
| C. | encoding P-galactosidase only |
| D. | None of the above |
| Answer» B. encoding p-galactosidase and galactose permeases | |
| 10. |
Signal peptide protein removal that is translocated across a membrane is accomplished by |
| A. | fMet aminopeptidase |
| B. | trypsin |
| C. | signal peptidase |
| D. | chymotrypsin |
| Answer» D. chymotrypsin | |
| 11. |
The first step in translation is |
| A. | binding of the two ribosomal subunits to each other |
| B. | binding of mRNA to the two ribosomal subunits |
| C. | binding of tRNA to the small ribosomal subunit |
| D. | binding of mRNA to the small ribosomal subunit |
| Answer» E. | |
| 12. |
The site of protein synthesis is |
| A. | Ribosome |
| B. | Nucleus |
| C. | Endoplasmic reticulum |
| D. | Chromosome |
| Answer» B. Nucleus | |
| 13. |
Which of the following amino acid starts all proteins synthesis? |
| A. | Glycine |
| B. | Proline |
| C. | Thymine |
| D. | Methionine |
| Answer» E. | |
| 14. |
The growing polypeptide chain is released from the ribosomes when |
| A. | a chain terminating codon is reached |
| B. | a chain terminating tRNA binds to the ribosome |
| C. | the 7-methyl guanosine cap is reached |
| D. | the poly A tail is reached |
| Answer» B. a chain terminating tRNA binds to the ribosome | |
| 15. |
Which of the following RNAs bind to an amino acid? |
| A. | mRNA |
| B. | tRNA |
| C. | rRNA |
| D. | hnRNA |
| Answer» C. rRNA | |
| 16. |
How many bases of nucleic acid determine a single amino acid? |
| A. | Four |
| B. | One |
| C. | Two |
| D. | Three |
| Answer» E. | |
| 17. |
Which is required for protein synthesis? |
| A. | tRNA |
| B. | mRNA |
| C. | rRNA |
| D. | All of these |
| Answer» E. | |
| 18. |
Amino acids are joined together into a protein chain by which of the following? |
| A. | Transfer RNA |
| B. | DNA polymerase |
| C. | Hydrogen bonds |
| D. | Messenger RNA |
| Answer» B. DNA polymerase | |
| 19. |
The anticodon of tRNA |
| A. | binds to rRNA |
| B. | binds to an amino acid |
| C. | binds to the Shine Dalgarno sequence |
| D. | binds to an mRNA codon |
| Answer» E. | |
| 20. |
Which site of the tRNA molecule binds to the mRNA molecule? |
| A. | Anticodon |
| B. | Codon |
| C. | Amino acid |
| D. | 5 prime end |
| Answer» B. Codon | |
| 21. |
The direction of amino acid transfer to the growing polypeptide chain is |
| A. | from the A (aminoacyl tRNA site) site to the P (peptidyl tRNA site) site on the ribosome |
| B. | from the P site to the A site on the ribosome |
| C. | from the A site to the E (exit tRNA site) site on the ribosome |
| D. | from the P site to the E site on the ribosome |
| Answer» C. from the A site to the E (exit tRNA site) site on the ribosome | |
| 22. |
The pathway of a tRNA during polypeptide elongation on the ribosome is |
| A. | A site P site E site |
| B. | P site entry site exit site |
| C. | A site P site entry site |
| D. | P site A site E site |
| Answer» B. P site entry site exit site | |
| 23. |
Which of the following has unusual bases? |
| A. | mRNA |
| B. | tRNA |
| C. | rRNA |
| D. | hnRNA |
| Answer» C. rRNA | |
| 24. |
The peptidyl transferase reaction occurs |
| A. | on the large subunit |
| B. | on the small subunit |
| C. | between the subunit |
| D. | none of these |
| Answer» B. on the small subunit | |
| 25. |
The site on a bacterial chromosome that marks the termination point for chromosome replication is called |
| A. | <i>ter</i> |
| B. | a stop codon. |
| C. | a stem-loop |
| D. | <i>pau</i> |
| Answer» B. a stop codon. | |
| 26. |
Processive synthesis is a characteristic feature of |
| A. | all DNA polymerases. |
| B. | DNA Pol III at a replication fork. |
| C. | removal of RNA primers on Okasaki fragments. |
| D. | DNA mismatch repair |
| Answer» C. removal of RNA primers on Okasaki fragments. | |
| 27. |
On the ribosome, mRNA binds |
| A. | between the subunits |
| B. | to the large subunit |
| C. | to the small subunit |
| D. | none of these |
| Answer» D. none of these | |
| 28. |
Type I proteins (plasma membrane) have a |
| A. | cleavage N- terminal signal sequence and a hydrophobic stop transfer sequence |
| B. | cleavaged N- terminal signal sequence that doubles as the membrane anchoring sequence |
| C. | multiple signal sequence and a hydrophobic stop transfer sequence |
| D. | multiple signal sequence that doubles as the membrane anchoring sequence |
| Answer» B. cleavaged N- terminal signal sequence that doubles as the membrane anchoring sequence | |
| 29. |
Which of the following is not a necessary component of translation? |
| A. | Anticodon |
| B. | mRNA |
| C. | Ligase |
| D. | Amino acid |
| Answer» D. Amino acid | |
| 30. |
A polysome could be best described as |
| A. | an active site of DNA synthesis. |
| B. | an active site of protein synthesis. |
| C. | an active site of lipid synthesis. |
| D. | all of the above. |
| Answer» C. an active site of lipid synthesis. | |
| 31. |
Eukaryotic mRNA binding to the ribosomes is facilitated by __________ . |
| A. | the Shine Dalgarno sequence |
| B. | the 7-methyl guanosine cap |
| C. | tRNA |
| D. | poly A tail |
| Answer» C. tRNA | |
| 32. |
Translation in prokaryotes begins by the formation of a 30S initiation complex between the |
| A. | 30S ribosomal subunit, mRNA, initiation factors and N-fMet tRNA |
| B. | 30S ribosomal subunit, tRNA and initiation factors |
| C. | 30S ribosomal subunit and mRNA only |
| D. | 30S ribosomal subunit, mRNA and initiation factors |
| Answer» B. 30S ribosomal subunit, tRNA and initiation factors | |
| 33. |
The ribosomes are composed of |
| A. | proteins |
| B. | RNA |
| C. | both (a) and (b) |
| D. | lipids |
| Answer» D. lipids | |
| 34. |
Ribosomes select the correct tRNAs |
| A. | then bind to the appropriate mRNA |
| B. | solely on the basis of their anticodons |
| C. | depending on their abundance in the cytosol |
| D. | with the least abundant anticodons |
| Answer» C. depending on their abundance in the cytosol | |
| 35. |
The structure in a bacterium that indicates an active site for protein synthesis is |
| A. | a chromosome. |
| B. | a cell membrane, |
| C. | a flagellum. |
| D. | a polysome. |
| Answer» E. | |
| 36. |
Which of the following is not necessary for protein synthesis to occur, once transcription is completed? |
| A. | tRNA |
| B. | Ribosomes |
| C. | mRNA |
| D. | DNA |
| Answer» E. | |
| 37. |
Degenerated codon differs mostly in |
| A. | the identities of their second base |
| B. | the identities of their third base |
| C. | the wobble position |
| D. | both (b) and (c) |
| Answer» E. | |
| 38. |
Phosphorus is taken up by the cell during the process of |
| A. | carbohydrate synthesis. |
| B. | protein synthesis, |
| C. | lipid synthesis. |
| D. | ATP synthesis. |
| Answer» E. | |