Questions and answers for exam Preparation

MCQs

Total Questions : 232 | Page 2 of 24 pages

Question 11. If a ligation reaction is being carried out and recircularization is observed, which type of reaction is being carried out?

Intramolecular
Intermolecular
Both observe recircularization equally
Recirculation is not possible in any of the cases

Discuss Question

Answer: Option A. -> Intramolecular
Answer: (a).Intramolecular

Question 12. Enzyme commonly used for carrying out ligation reaction is ____________

Transferase
Reverse transciptase
Ligase
DNase

Discuss Question

Answer: Option C. -> Ligase
Answer: (c).Ligase

Question 13. What are the effects of increasing concentration of reaction components?

It increases chances of ligation in both intramolecular and intermolecular reactions
It increases chances of ligation only in intermolecular and no effect on intramolecular
It decreases chances of ligation in intramolecular and increases in that of intermolecular
It decreases chances of ligation in both types of reaction

Discuss Question

Answer: Option B. -> It increases chances of ligation only in intermolecular and no effect on intramolecular
Answer: (b).It increases chances of ligation only in intermolecular and no effect on intramolecular

Question 14. What is the kinetics of the intramolecular and intermolecular ligation reactions?

Second order kinetics for intramolecular and first order for intermolecular
First order kinetics for intramolecular and second order for intermolecular
Both are first order
Both are second order

Discuss Question

Answer: Option B. -> First order kinetics for intramolecular and second order for intermolecular
Answer: (b).First order kinetics for intramolecular and second order for intermolecular

Question 15. Which of the following statements is correct with respect to T4 DNA ligase?

It can carry out only blunt ended ligations
It doesn’t requires ATP
It requires a phosphate group at 3’ end and a hydroxyl group at 5’ end for the molecule to be joined
It is obtained from T4 bacteriophage upon infection by E. coli

Discuss Question

Answer: Option D. -> It is obtained from T4 bacteriophage upon infection by E. coli
Answer: (d).It is obtained from T4 bacteriophage upon infection by E. coli

Question 16. If blunt ended ligations are to be carried out. Which of the following enzymes can be used?

E. coli DNA ligase
T4 DNA ligase
Both of these enzymes act equally in carrying out blunt ended ligations
None of them is able to carry out blunt ended ligations

Discuss Question

Answer: Option B. -> T4 DNA ligase
Answer: (b).T4 DNA ligase

Question 17. Mechanism of ligation for both T4 DNA ligase and E. coli DNA ligase makes use of Adenosine Monophosphate (AMP). Which of the steps is involved in the ligation mechanism?

AMP is added to the 5’ phosphate of one of the DNA molecule
It leads to the liberation of pyrophosphate from NAD and nicotinamide mononucleotide from ATP
The AMP is further displaced by an electrophilic attack
The AMP is further displaced by nucleophilic attack by 3’ hydroxyl of the same DNA molecule

Discuss Question

Answer: Option A. -> AMP is added to the 5’ phosphate of one of the DNA molecule
Answer: (a).AMP is added to the 5’ phosphate of one of the DNA molecule

Question 18. E. coli DNA ligase doesn’t require a cofactor.