This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “DNA Repair”.
1. If the mutation has a negligible effect on the function of a gene, it is known as a ____________
a) Silent mutation
b) Frame shift mutation
c) Substitution mutation
d) Insertion mutation
View Answer
Explanation: Mutations can involve the replacement of one base pair with another (substitution mutation) or the addition or deletion of one or more base pairs (insertion or deletion mutations).
2. Which of the following mechanisms will remove uracil and incorporate the correct base?
a) Direct repair
b) Base excision repair
c) Mismatch repair
d) Nucleotide excision repair
View Answer
Explanation: Base excision repair is responsible for removing small, non-helix-distorting base lesions from genome.
3. Which of the following has the self-repairing mechanisms?
a) DNA and RNA
b) DNA, RNA and protein
c) Only DNA
d) DNA and proteins
View Answer
Explanation: Only DNA has a self-repairing mechanism.
4. What is the function of enzyme involved in base excision repair?
a) Addition of correct base
b) Addition of correct nucleotide
c) Removal of incorrect base
d) Removal of phosphodiester bond
View Answer
Explanation: DNA glycosylases are responsible for the removal of the incorrect base in base excision repair.
5. The DNA polymerase involved in base excision repair is ____________
a) DNA polymerase α
b) DNA polymerase β
c) DNA polymerase σ
d) DNA polymerase γ
View Answer
Explanation: DNA polymerase β is involved in base excision repair.
6. An alteration in a nucleotide sequence that changes a triplet coding for an amino acid into a termination codon is ____________
a) Nonsense mutation
b) Mutagenesis
c) Mutation
d) Mutagen
View Answer
Explanation: Nonsense mutation (point mutation) results in a premature stop codon.
7. A point mutation that replaces a purine with another purine, or a pyrimidine with another pyramidine ____________
a) Nonsense mutation
b) Silent mutation
c) Transition mutation
d) Transversion
View Answer
Explanation: Nonsense mutation (point mutation) results in a premature stop codon.
Transversion refers to substitution of a purine for a pyrimidine or vice-versa.
If the mutation has a negligible effect on the function of a gene, it is known as a silent mutation.
8. The enzyme of E.coli is a nuclease that initiates the repair of double stranded DNA breaks by homologous recombination is?
a) DNA glycosylase
b) DNA ligase
c) DNA polymerase
d) RNA polymerase
View Answer
Explanation: DNA glycosylase catalyzes the first step of base excision repair in DNA.
9. Recombinational repair is often due to ____________
a) Incorporation of many incorrect nucleotides by DNA pol
b) Many cystidine dimer and associated large gaps in a strand
c) Many thymidine dimer formations and associated large gaps in a strand
d) All of the mentioned
View Answer
Explanation: Recombinational repair is often due to many thymidine dimer formations and associated large gaps in a strand.
10. The enzyme photolyase is used in what method of repair?
a) Base excision
b) Photo reactivation
c) Nucleotide excision
d) None of the mentioned
View Answer
Explanation: They repair the damage caused by exposure to ultraviolet light. It is used in photo reactivation mechanism.
Sanfoundry Global Education & Learning Series – Biochemistry.
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