Which of these enzymes is required to cleave a plasmid?
Show Hint
Restriction enzymes are indispensable tools in molecular biology.
- Ligase
- Endonuclease
- Exonuclease
- Polymerase
The Correct Option is B
Approach Solution - 1
The enzyme required to cleave a plasmid is Endonuclease.
(A) Ligase - Incorrect: DNA ligase joins DNA fragments, it doesn't cut them.
(B) Endonuclease - Correct: Restriction endonucleases (like EcoRI) cut plasmid DNA at specific recognition sites.
(C) Exonuclease - Incorrect: These remove nucleotides from DNA ends, not make internal cuts.
(D) Polymerase - Incorrect: DNA polymerase synthesizes DNA, it doesn't cleave it.
The correct answer is (B) Endonuclease, specifically restriction enzymes that create "sticky ends" for recombinant DNA technology.
Approach Solution -2
Endonucleases are enzymes that cleave phosphodiester bonds within a nucleic acid strand, typically in the middle of a DNA molecule. These enzymes are used to cut plasmids or DNA into smaller fragments.
- Ligase is an enzyme used to join two strands of DNA.
- Exonuclease removes nucleotides from the ends of DNA molecules.
- Polymerase is used to synthesize DNA or RNA by adding nucleotides to the ends of the strand.
Option (B) is correct because endonucleases are responsible for cleaving plasmids.
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Codes:
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