Questions and answers for exam Preparation

MCQs

Total Questions : 232 | Page 9 of 24 pages

Question 81. Basic classification of polymerases includes how many types?

Discuss Question

Answer: Option D. -> 5
Answer: (d).5

Question 82. Which of the following activity is not possible in the case of DNA polymerase I?

3’-5’ exonuclease
5’-3’ exonuclease
5’-3’ DNA synthesis
3’-5’ DNA synthesis

Discuss Question

Answer: Option D. -> 3’-5’ DNA synthesis
Answer: (d).3’-5’ DNA synthesis

Question 83. The E. coli DNA polymerase enzyme gives different domains with different activities on cleaving with protease subtilisin. Which of the following statements is correct with respect to the fragments generated?

The smaller fragment is having C terminal and the larger fragment is having N terminal
The smaller fragment is named as Klenow fragment and the intact molecule is called as Kornberg fragment
The smaller fragment is having 5’-3’ exonuclease activity whereas the larger fragment is having 5’-3’ polymerase and 3’-5’ exonuclease activity
Both the fragments are having 5’-3’ polymerase and 3’-5’ exonuclease activity

Discuss Question

Answer: Option C. -> The smaller fragment is having 5’-3’ exonuclease activity whereas the larger fragment is having 5’-3’ polymerase and 3’-5’ exonuclease activity
Answer: (c).The smaller fragment is having 5’-3’ exonuclease activity whereas the larger fragment is having 5’-3’ polymerase and 3’-5’ exonuclease activity

Question 84. Removal of single stranded portions produced due to exonucleolytic activity and due to polymerase activity are termed as _____________

polishing and end filling respectively
end filling and polishing respectively
polishing in both the cases
end filling in both the cases

Discuss Question

Answer: Option A. -> polishing and end filling respectively
Answer: (a).polishing and end filling respectively

Question 85. Thermostable DNA polymerases are very important in PCR. How are they obtained?

They are obtained by heating the bacteria manually over high temperatures
They are isolated from extremely stable thermophilic bacteria which are often found growing in oceanic vents
They are found everywhere in nature
They are obtained by genetically modifying the E. coli bacteria with thermal stability property

Discuss Question

Answer: Option B. -> They are isolated from extremely stable thermophilic bacteria which are often found growing in oceanic vents
Answer: (b).They are isolated from extremely stable thermophilic bacteria which are often found growing in oceanic vents

Question 86. Why reverse transcriptase enzymes are having comparatively high error rates than other polymerases?

Because they are not having 3’-5’ proofreading exonucleolytic activity
Because they are not having 5’-3’ proofreading exonucleolytic activity
Because they are having slow rates of exonucleolytic activity
It is difficult to synthesize DNA from RNA

Discuss Question

Answer: Option A. -> Because they are not having 3’-5’ proofreading exonucleolytic activity
Answer: (a).Because they are not having 3’-5’ proofreading exonucleolytic activity

Question 87. Which of the following enzyme is said as reverse transcriptase?

DNA dependent DNA polymerase
RNA dependent RNA polymerase
RNA dependent DNA polymerase
DNA dependent RNA polymerase

Discuss Question

Answer: Option C. -> RNA dependent DNA polymerase
Answer: (c).RNA dependent DNA polymerase

Question 88. Which polymerase can be used in conjunction with appropriate phage promoters in order to have high levels of specific transcription?

RNA dependent DNA polymerase
DNA dependent RNA polymerase
RNA dependent RNA polymerase
DNA dependent DNA polymerase

Discuss Question

Answer: Option B. -> DNA dependent RNA polymerase
Answer: (b).DNA dependent RNA polymerase

Question 89. How many approaches are there which can be used for exonucleolytic activity in double stranded DNA molecules?

Discuss Question

Answer: Option B. -> 2
Answer: (b).2

Question 90. What is the mode of action of exonuclease III?

Exonuclease III acts on single stranded DNA in 3’-5’ direction
Exonuclease III acts on double stranded DNA in 5’-3’ direction
Exonuclease III acts on single stranded DNA in 5’-3’ direction
Exonuclease III acts on double stranded DNA in 3’-5’ direction

Discuss Question

Answer: Option D. -> Exonuclease III acts on double stranded DNA in 3’-5’ direction
Answer: (d).Exonuclease III acts on double stranded DNA in 3’-5’ direction