DNA Repair Mechanisms: Biology MCQ 019 with Answer Key (Model Questions for CSIR NET and GATE Life Sciences Examination, December 2015)

MECHANISTIC STUDIES OF DNA REPAIR

1. Which of the following DNA repair mechanism is known as the ‘cut and patch mechanism’?

a.       Photoreactivation
b.      Nucleotide excision repair
c.       Base excision repair
d.      Mismatch repair

2. DNA helicase enzyme involved in base excision repair mechanism is______.

a.       DNA helicase I
b.      DNA helicase II
c.       DNA helicase III
d.      DNA helicase IV

3. In mismatch repair mechanism, which of the following protein recognize DNA mismatches in the genomic DNA?

a.       MutH
b.      MutS
c.       MutL
d.      UvrD

4. The main difference between nucleotide excision repair  (NER) and base excision repair (BER) is:

a.       In NER double strand breaks are repaired where as in BER single strand breaks repaired
b.      NER is a light dependent reaction whereas BER is light independent process
c.       In NER phosphodiester backbone is first cleaved where as in BER phosphodiester backbone is cleaved later
d.      All of these

5. Which enzyme is responsible for photoreactivation of DNA:

a.       Photoligase
b.      Photoreductase
c.       Photo-oxidase
d.      Photolyase

6. Which of the following enzyme(s) is involved base excision repair?

a.       DNA glycosylase
b.      AP endonuclease
c.       AP exonuclease
d.      (a), (b) and (c)
e.       Both (a) and (b)

7. Xeroderma pigmentosum in human is associated with a mutation in

a.       Photoreactivation
b.      Nucleotide excision repair
c.       Base excision repair
d.      Mismatch repair

8. Which of the following gene is NOT involved in mismatch repair system in bacteria?

a.       MutS
b.      MutA
c.       MutL
d.      UvrD

9. In eukaryotes, the mismatch repair mechanism is initiated and directed by_____.

a.       Methylated DNA strand
b.      Acetylated DNA strand
c.       Strand specific nicks
d.      Double strand breaks

10.  In nucleotide excision repair mechanism which of the following proteins first recognize DNA lesion?

a.       UvrA
b.      UvrB
c.       UvrC
d.      UvrD

11.  The two chromophores present in photolyase enzyme are:

a.       NAD and FAD
b.      FAD and Folate
c.       FADH and Folate –
d.      FAD – and Folate

12.  Which of the following statement is true regarding the nucleotide excision repair (NER) mechanism?

a.       NER mechanism is present only in eukaryotes
b.      NER present only in prokaryotes
c.       NER Present in both prokaryotes and eukaryotes but the exact mechanisms varies
d.      NER Present in both prokaryotes and eukaryotes with similar molecular mechanism in both

13.  Photolyase enzyme involved in the photoreactivation can remove ______.

a.       UV induced double strand breaks
b.      UV induced thymine dimers
c.       Mismatches in DNA
d.      Single strand breaks in DNA

14.  DNA polymerase enzyme involved in base excision repair mechanism is ______.

a.       Pol-α
b.      Pol-β
c.       Pol-γ
d.      Pol-δ

15.  DNA polymerase enzyme involved in mismatch repair system of E. coli is ______.

a.       DNA Pol-I
b.      DNA Pol-II
c.       DNA Pol-III
d.      DNA Pol-β

16.  In NER machinery, which of the following protein processes the helicase activity?

a.       UvrA
b.      UvrB
c.       UvrC
d.      UvrD

17.  The catalytic activity of photolyase enzyme in the bacterial cells is activated by _____.

a.       UV light
b.      IR light
c.       Visible light near blue region
d.      Visible light near red region

18.  In NER (nucleotide excision repair) mechanism, the incision at the 3’ position of the lesion is done by______.

a.       Uvr A
b.      UvrB
c.       UvrC
d.      UvrD

19.  In mismatch repair mechanism, the endonuclease activity which cut the nascent DNA strand is done by:

a.       MutH
b.      MutL
c.       MutS
d.      UvrD

20.  The activity of AP endonuclease is involved in ________.

a.       Base excision repair
b.      Nucleotide excision repair
c.       Mismatch repair
d.      Double strand break repair

21.  Which of the following statement is correct?

a.       Photoreactivation is absent in human
b.      Photoreactivation is present in all organism
c.       Photoreactivation present only in plants and animals
d.      Photoreactivation is present only in bacteria

22.  The enzyme photolyase repair the thymine dimer in the DNA by __________ mechanism.

a.       Oxidation mechanism
b.      Free radical mechanism
c.       Direct bond breaking
d.      Adduct formation

23.  In E. coli, inactivation of cellular DNA methylase enzyme causes severe mutation in the genomic DNA. Which of the following DNA repair mechanism would be most probably inhibited?

a.       Double strand break repair
b.      Mismatch repair
c.       Base Excision Repair
d.      Nucleotide Excision Repair

24.  The function of UvrC in NER mechanism is_________.

a.       To identify the lesion in the DNA
b.      Helicase activity to unwind the DNA
c.       Catalyze the incision at the 3’ end of the lesion
d.      Catalyze the incision at the 5’ side of the lesion

25.  First DNA glycosylase enzyme discovered is ___________.

a.       Uracil DNA glycosylase
b.      Thymine DNA glycosylase
c.       Adenine DNA glycosylase
d.      Methyl Adenine Glycosylase


More Molecular Biology MCQs

Molecular Biology Quizzes


DNA Repair Mechanisms MCQ 019:  Answer Key

1. Ans. (b). Nucleotide excision repair

2. Ans. (c). DNA helicase III

3. Ans. (b). MutS

4. Ans. (c). In NER phosphodiester backbone is first cleaved where as in BER phosphodiester backbone is cleaved later

5. Ans. (d). Photolyase

6. Ans. (e). Both (a) and (b)

7. Ans. (b). Nucleotide excision repair

8. Ans. (b). MutA

9. Ans. (c). Strand specific nicks

10. Ans. (a). UvrA

11. Ans. (d). FAD – and Folate

12. Ans. (c). NER present in both prokaryotes and eukaryotes but the exact mechanism varies

13. Ans. (b). UV induced thymine dimer

14. Ans. (b). Pol-β

15. Ans. (c). DNA Pol-III

16. Ans. (d). UvrD

17. Ans. (c). Visible light near blue region

18. Ans. (b). UvrB

19. Ans. (a). MutH

20. Ans. (a). Base excision repair

21. Ans. (a). Photoreactivation is present in human

22. Ans. (b). Free radical mechanism

23. Ans. (b). Mismatch repair

24. Ans. (d). Catalyze the incision at 5’ side of the lesion

25. Ans. (a). Uracil DNA glycosylase


Get Updates on Molecular Biology Posts
We will not spam your account…

Enter your e-mail address


You may also like…

@. Biochemistry MCQ

@. Biophysics MCQ

@. CSIR Previous Year Questions

@. GATE Previous Year Questions (BT, XL)

@. Free Online Mock Tests


Please Share for your Students, Colleagues, Friends and Relatives…

Facebooktwittergoogle_pluspinterestlinkedin
Posted in CSIR / ICMR / DBT / ICAR, MCQ (Multiple Choice Questions), Molecular Biology, Nobel Prize Discoveries and tagged , , , , , , , , , .