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Enzymes (Biochemistry) Question and Answers-Page first

Enzymes problems


  • 1. The nucleophile in serine proteases is

  • Options
  • A. Serine
  • B. water
  • C. both (a) and (b)
  • D. Asparagine
  • Discuss
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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

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