Life Sciences Questions and Answers – Enzymes for DNA Manipulation

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This set of Life Sciences online test focuses on “Enzymes for DNA Manipulation”.

1. An enzyme which synthesis, DNA from RNA is called___________
a) DNA polymerase
b) RNA polymerase
c) Nucleases
d) Reverse transcriptase
View Answer

Answer: d
Explanation: Reverse transcriptase was discovered by Howard Temin at the University of Wisconsin, also known as RNA directed DNA polymerase which synthesis DNA from RNA.
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2. Kornberg enzyme has both 3’-5’ and 5’-3’ exonuclease activity.
a) True
b) False
View Answer

Answer: a
Explanation: Kornberg enzyme is DNA polymerase I, which have exclusively both 3’ -5’ and 5’-3’ exonuclease activity. It also has 5’-3’ polymerase activity.

3. Name the bacterium from which Taq DNA polymerase derived?
a) Thermus aquaticus
b) Salmonella
c) Cyanobacteria
d) E.coli
View Answer

Answer: a
Explanation: Taq polymerase derived from thermostable bacteria called thermus aquaticus.it is basically used in PCR and have the ability to withstand with 90°C temperature.
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4. Name the enzyme which degrades DNA molecule by breaking its phosphodiester bonds?
a) DNA polymerase
b) Nucleases
c) Ligase
d) Reverse transcriptase
View Answer

Answer: b
Explanation: Nucleases are the enzymes which break phosphodiester bonds of DNA that link one nucleotide to another. Nucleases are of two types i.e., endonucleases and exonucleases.

5. Which of the following is NOT an endonuclease?
a) Mung bean nuclease
b) S1 nuclease
c) Terminal deoxynucleotidal transferase
d) RNase A
View Answer

Answer: c
Explanation: Endonuclease are those which break internal phosphodiester bonds of DNA while exonuclease removes nucleotide from the end of the DNA. Examples: mung bean nuclease, S1 nuclease, Rnase A, and RNase H.
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6. Which of the following endonuclease has been purified from Aspergillus oryzae?
a) S1 nuclease
b) RNase H
c) RNase A
d) Mung bean nuclease
View Answer

Answer: a
Explanation: S1 nuclease has been derived from Aspergillus oryaze and used to degrade single strand RNA and DNA but does not affect ds DNA or DNA-RNA hybrid.

7. Name the enzyme which degrade dsDNA after recognizing specific nucleotide sequences?
a) RNase H
b) Restriction endonuclease
c) DNA polymerase
d) Ligases
View Answer

Answer: b
Explanation: Restriction endonuclease is also called restriction enzymes and works on the specific nucleotide sequence called restriction site. These enzymes restrict the entry of foreign DNA into bacteria.
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8. Which of the following is NOT the property of restriction enzymes?
a) Recognizes palindromic sequences
b) Two fold axial symmetry
c) Recognize specific site according to DNA sources
d) Cut down randomly
View Answer

Answer: c
Explanation: Restriction enzyme recognizes specific restriction sites which are independent of DNA sources.

9. Which of the following type of restriction enzyme does not require ATP for cleavage?
a) Type I
b) Type II
c) Type III
d) Type IV
View Answer

Answer: b
Explanation: On the basis of properties restriction enzymes has been divided into type I, type II, and type III. Type I and Type III require ATP and magnesium while Type II requires only magnesium.
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10. Name the restriction enzyme which recognizes different sequences, but produces same ends?
a) DAM methylase
b) Isoschizomers
c) Neoschizomers
d) Isocaudomers
View Answer

Answer: d
Explanation: Isocaudomers recognizes different sequences but produces same ends while Isoschizomers recognizes the same sequences and cut in the same pattern.

11. Which enzyme join DNA molecules together?
a) Polymerase
b) Nucleases
c) Ligases
d) Linkers
View Answer

Answer: c
Explanation: DNA ligases are used to join DNA molecules together by synthesizing phosphodiester bond between the nucleotides.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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