MCQOPTIONS
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MCQOPTIONS
This section includes 15 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 (s) is/are serine proteases? |
| A. | Chymotrypsin |
| B. | Trypsin |
| C. | Elastase |
| D. | all of these |
| Answer» E. | |
| 2. |
Which of the following statements about enzymes or their function is true? |
| A. | Enzymes do not alter the overall change in free energy for a reaction |
| B. | Enzymes are proteins whose three-dimensional form is key to their function |
| C. | Enzymes speed up reactions by lowering activation energy |
| D. | All of the above |
| Answer» E. | |
| 3. |
Tryprotophan synthetase of E.coli, a typical bifunctional oligomeric enzyme consist of |
| A. | a protein designated A |
| B. | two proteins designated A and B |
| C. | a protein A and one-subunit a |
| D. | a protein designated B |
| Answer» C. a protein A and one-subunit a | |
| 4. |
What is the specificity of the Clostripain protease? |
| A. | It cleave after Arg residues |
| B. | It cleave after His residues |
| C. | It cleave after Lys residues |
| D. | None of the above |
| Answer» B. It cleave after His residues | |
| 5. |
Which of the common features are shared between serine and aspartate proteases? |
| A. | Both require water to complete the catalytic cycle |
| B. | Both use a base to activate the nucleophile |
| C. | Both show specificity for certain amino acid sequences |
| D. | All of the above |
| Answer» E. | |
| 6. |
Before they can react, many molecules need to be destabilized. This state is typically achieved through |
| A. | changing the three-dimensional shape of the molecule |
| B. | oxidizing the molecules by removing electrons |
| C. | changing the reaction from a biosynthetic to a catabolic pathway |
| D. | the input of a small amount of activation energy |
| Answer» E. | |
| 7. |
Common feature in all serine proteases is a |
| A. | hydrophobic specificity pocket |
| B. | hydrophilic specificity pocket |
| C. | cluster of reactive serine residues |
| D. | single reactive serine residue |
| Answer» E. | |
| 8. |
In the enzyme-catalyzed reaction shown below, what will be the effect on substances A, B, C, and D of inactivating the enzyme labeled E2? |
| A. | A, B, C, and D will all still be produced |
| B. | A, B, and C will still be produced, but not D |
| C. | A and B will still be produced, but not C or D |
| D. | A will still be produced, but not B, C, or D |
| Answer» D. A will still be produced, but not B, C, or D | |
| 9. |
How is the enzyme COX-1 important in human health? |
| A. | It helps to transport carbon dioxide in the blood |
| B. | It is critical for the biosynthesis of DNA |
| C. | It is a chemical derivative of aspirin |
| D. | It catalyzes the production of hormones that maintain the stomach lining |
| Answer» E. | |
| 10. |
The cleavage specificity of trypsin and chymotrypsin depend in part on the |
| A. | proximity of Ser 195 to the active site or specificity pocket |
| B. | size, shape, and charge of the active site or specificity pocket |
| C. | presence of a low-barrier hydrogen bond in the active site or specificity pocket |
| D. | absence of water in the active site |
| Answer» C. presence of a low-barrier hydrogen bond in the active site or specificity pocket | |
| 11. |
The proteolysis rate enhancement by chymotrypsin (~1010 folds) corresponds to a reduction in activation energy of about |
| A. | 40 kJ/mol |
| B. | 49 kJ/mol |
| C. | 58 kJ/mol |
| D. | 88 kJ/mol |
| Answer» D. 88 kJ/mol | |
| 12. |
Which of the following is false statement with regard to comparison between Serine and HIV proteases? |
| A. | Both use nucleophilic attack to hydrolyze the peptide bond |
| B. | Both require water to complete the catalytic cycle |
| C. | Both forms an acyl-enzyme intermediate |
| D. | Both show specificity for certain amino acid sequences |
| Answer» D. Both show specificity for certain amino acid sequences | |
| 13. |
The role of Asp 102 and His 57 during trypsin catalysis is to |
| A. | neutralize the charge on the other's side chain |
| B. | keep the specificity pocket open |
| C. | function as a proton shuttle |
| D. | clamp the substrate into the active site |
| Answer» D. clamp the substrate into the active site | |
| 14. |
Enzyme-driven metabolic pathways can be made more efficient by |
| A. | concentrating enzymes within specific cellular compartments |
| B. | grouping enzymes into free-floating, multienzyme complexes |
| C. | fixing enzymes into membranes so that they are adjacent to each other |
| D. | All of the above |
| Answer» E. | |
| 15. |
The nucleophile in serine proteases is |
| A. | Serine |
| B. | water |
| C. | both (a) and (b) |
| D. | Asparagine |
| Answer» D. Asparagine | |