Enzymes problems
- 1. The nucleophile in serine proteases is
Options- A. Serine
- B. water
- C. both (a) and (b)
- D. Asparagine Discuss
Correct Answer: both (a) and (b)
- 2. Enzyme-driven metabolic pathways can be made more efficient by
Options- 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 Discuss
Correct Answer: All of the above
- 3. 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 ---(E1)---> B ---(E2)---> C ---(E3)--->
Options- 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 Discuss
Correct Answer: A and B will still be produced, but not C or D
- 4. Before they can react, many molecules need to be destabilized. This state is typically achieved through
Options- 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 Discuss
Correct Answer: the input of a small amount of activation energy
- 5. Which of the following statements about enzymes or their function is true?
Options- 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 Discuss
Correct Answer: All of the above
- 6. The proteolysis rate enhancement by chymotrypsin (~1010 folds) corresponds to a reduction in activation energy of about
Options- A. 40 kJ/mol
- B. 49 kJ/mol
- C. 58 kJ/mol
- D. 88 kJ/mol Discuss
Correct Answer: 58 kJ/mol
- 7. Common feature in all serine proteases is a
Options- A. hydrophobic specificity pocket
- B. hydrophilic specificity pocket
- C. cluster of reactive serine residues
- D. single reactive serine residue Discuss
Correct Answer: single reactive serine residue
- 8. What is the specificity of the Clostripain protease?
Options- A. It cleave after Arg residues
- B. It cleave after His residues
- C. It cleave after Lys residues
- D. None of the above Discuss
Correct Answer: It cleave after Arg residues
- 9. Tryprotophan synthetase of E.coli, a typical bifunctional oligomeric enzyme consist of
Options- 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 Discuss
Correct Answer: two proteins designated A and B
- 10. Which of the following is false statement with regard to comparison between Serine and HIV proteases?
Options- 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 Discuss
Correct Answer: Both forms an acyl-enzyme intermediate
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