Multiple Choice Questions on DNA Repair

DNArepair1. Which of the following biomolecule has self-repair mechanisms?
a) DNA,RNA and protein
b) DNA and RNA
c) DNA only
d) DNA and proteins

 2. Which of the following chemicals induce depurination
a) methyl ethane sulphonate (MES)
b) nitrosoguanidine
c) ethyl ethane sulphonate (EES)
d) all of these

 3. Which of the following mechanism of DNA polymerase helps in preventing error during DNA replication
a) rechecking
b) proof checking
c) proof reading
d) all of these

 4. The proteins involved in mismatch repair are
Mismatch Repair
a) Mut S
b) Mut H
c) Mut L
d) all of these

5. Which of the following dimer formation is most common
a) thymidine dimer
b) cytidine dimer
c) both a and b
d) none of these

 6. Dimer repair mechanism include
a) excision repair
b) photoreactivation
c) recombinational repair
d) all of these

 7. Thymine dimers are often corrected by light induced repair mechanism. The enzyme involved in the process is
a) photolyase
b) photoligase
c) DNA glycosylase
d) All of these

 8. Which of the following is dark repair
a) nucleotide excision repair (NER)
b) base excision repair (BER)
c) both a and b
d) none of these

 9. DNA glycosylase is an enzyme involved in base excision repair. The function is
a) addition of correct base
b) addition of correct nucleotide
c) removal of incorrect base
d) removal of phosphodiester bond

 10. Recombinational repair is often due to
a) incorporation of many incorrect nucleotides by DNA polymerase
b) many cytidine dimer and associated large gaps in a strand
c) many thymidine dimer formation and associated large gaps in a strand
d) all of these

 11. Which is the DNA polymerase involved in BER
a) DNA polymerase α
b) DNA polymerase β
c) DNA polymerase σ
d) DNA polymerase £

 12. Which of the following is a bypass repair system
a) BER
b) NER
c) SOS
d) Recombinational repair

13. DNA repair mechanism is absent in
a) nuclear genome
b) mitochondrial genome
c) chloroplast genome
d) both b and c

 14. umu C, umu D gene family and Rec A proteins are involved in
a) BER
b) NER
c) SOS repair
d) Recombinational repair

15. The distortion in DNA helix due to pyrimidine dimer formation is called as
a) nick
b) single stranded breaks
c) kink
d) none of these
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Answers
1. c) DNA only
2. d) all of these
3. c) proof reading
4. d) all of these
5. a) thymidine dimer
6. d) all of these
7. a) photolyase
8. c) both a and b
9. c) removal of incorrect base
10. c) many thymidine dimer formation and associated large gaps in a strand
11. b) DNA polymerase β
12.  c) SOS
13. d) both b and c
14. c) SOS repair
15. c) kink
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