Question

1.Which of the following statements regarding the reversible binding of ligands to proteins is not true?

A) Proteins generally bind only specific ligands.

B) Sometimes, ligand binding causes conformational change of the protein.

C) In proteins composed of multiple subunits, the conformational change in one subunit can

lead to conformational change in other subunits.

D) Protein–ligand interaction can be regulated by a third molecule.

E) Proteins which have a large number of alpha helices are easier to regulate than those

composed mainly of beta sheets.

2. Which of the following proteins is used for oxygen storage?

A) myoglobin

B) ferritin
C) hemoglobin

D) antibody

E) chymotrypsin

3.Which of the following proteins is an enzyme?

A) serotonin transporter

B) cytokine

C) actin

D) chymotrypsin

E) None of the above.

4.Which force does nature use to hold a protein and its ligand together?

A) hydrogen bond interaction

B) electrostatic interaction

C) hydrophobic interaction

D) van der Waals interaction

E) All of the above.

5. Which of the following descriptions of the induced fit model is false?

A) It was proposed by Emil Fisher in 1894.

B) Conformational changes may occur in the protein upon ligand binding.

C) Conformational changes may occur in the ligand upon ligand binding.

D) It allows for tighter protein–ligand interaction compared to the lock and key model.

E) It allows for binding of different ligands.

6. Which of the following is true about the “R” state of hemoglobin?

A) It contains fewer interactions compared to the “T” state.

B) It has a higher affinity for oxygen.

C) It is more flexible compared to the “T” state.

D) It adopts the “R” state conformation when oxygen binds to the “T” state.

E) All of the above.

7. Most enzymes are proteins, but a small number of enzymes are ___________.

A) carbohydrates

B) lipids

C) deoxyribonucleic acids

D) ribonucleic acids

E) saccharides

8. Why do cells use enzymes to carry out biochemical reactions?

A) In order to regulate the reactions taking place inside the cell.

B) In order to carry out reactions without the use of organic solvents.

C) In order to minimize the production of side products.

D) In order to accelerate the rate of reactions.

E) All of the above.

9. Enzyme–substrate complex is also called the ___________?

A) Menten complex
B) enzyme–product complex

C) Michaelis complex
D) transition state complex

E) intermediate complex

10. Which of the following statements about enzymes is false?

A) Enzymes are biological catalysts.

B) Enzymes accelerate reactions by lowering the activation barrier.

C) Enzymes push the reaction equilibrium toward product formation.

D) Enzymes can denature under a highly acidic condition.

E) Enzymes carry out multiple rounds of a given chemical reaction.

11. Which of the following statements regarding enzyme inhibitors is true?

A) A reversible inhibitor typically deactivates an enzyme permanently.

B) Irreversible inhibitors are often structural analogs of substrates or products.

C) Reversible inhibitors are often used as therapeutic drugs.

D) Reversible inhibitors cannot bind to the free enzyme.

E) Potent toxins are generally reversible inhibitors.

Answer 1

1. Ans :- Statement (D) is wrong, because Protein - ligand binding can be both specific as well as non specific. Also protein ligand interacion only depends on concentration of ligand and structure of protein.

2. Ans :- Option (a) is the correct answer i.e. Myoglobin is protein which stores oxygen in the muscle

3. Ans :- Option (d) is the correct answer i.e. Chymotripsin, because it is a digestive enzyme secreted by pancrease which acts on protein in deodenum

4. Ans :- Option (d) is the correct answer i.e. all of the above , because ligand can bind to protein by using hydrogen bonding, electrostatic interaction, hydrophobic interaction and van der walls interaction.